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2018-soft-3d-renderer
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41 changed files with 2151 additions and 1979 deletions
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49
CMakeLists.txt
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@ -1,49 +0,0 @@
cmake_minimum_required(VERSION 3.14)
project(renderer)
set(CMAKE_CXX_STANDARD 17)
set(CMAKE_CXX_EXTENSIONS OFF)
set(CMAKE_CXX_STANDARD_REQUIRED ON)
find_package(SDL2 REQUIRED)
add_executable(renderer)
target_compile_options(
renderer
PRIVATE
-fno-exceptions
-Wall)
target_sources(
renderer
PRIVATE
Source/Engine.cpp
Source/Loader.cpp
Source/Main.cpp
Source/Platform.cpp
Source/Render.cpp
Source/Transform.cpp)
target_sources(
renderer
PRIVATE
Source/Camera.hpp
Source/Color.hpp
Source/Geometry.hpp
Source/Matrix.hpp
Source/Point.hpp
Source/Vec.hpp)
target_include_directories(
renderer
PRIVATE
Source)
target_link_libraries(
renderer
PRIVATE
SDL2::SDL2)

61
Makefile Normal file
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@ -0,0 +1,61 @@
# Verbosity of make output
ifeq ("$(VERBOSE)","1")
V :=
else
V := @
endif
# Optimizations
ifeq ("$(OPTIMIZE)","0")
O := -O0
else ifeq ("$(OPTIMIZE)","1")
O := -O1
else ifeq ("$(OPTIMIZE)", "2")
O := -O2
else ifeq ("$(OPTIMIZE)", "3")
O := -O3
else
O := -O3
endif
# Debugging
ifeq ("$(DEBUG)","1")
D := -g
else
D :=
endif
SRC_DIR=src
INCLUDE_DIR=include
BUILD_DIR=build
CC=clang++
WARNINGS_ON=-Weverything
WARNINGS_OFF=-Wno-missing-braces -Wno-gnu-anonymous-struct -Wno-old-style-cast\
-Wno-zero-as-null-pointer-constant -Wno-nested-anon-types\
-Wno-padded -Wno-exit-time-destructors -Wno-global-constructors\
-Wno-c++98-compat
CFLAGS=$(D) $(O) -std=c++11 $(WARNINGS_ON) $(WARNINGS_OFF) -I$(INCLUDE_DIR)
LIBS=-lSDL2
_HEADERS = camera.h color.h engine.h geometry.h light.h loader.h matrix.h\
platform.h point.h render.h transform.h util.h vec.h
HEADERS = $(patsubst %,$(INCLUDE_DIR)/%,$(_HEADERS))
_OBJS = engine.o light.o loader.o main.o platform.o render.o\
transform.o
OBJS = $(patsubst %,$(BUILD_DIR)/%,$(_OBJS))
$(BUILD_DIR)/%.o: $(SRC_DIR)/%.cpp $(HEADERS)
@ if [ ! -d $(BUILD_DIR) ]; then mkdir $(BUILD_DIR); fi
$(V) $(CC) -c -o $@ $< $(CFLAGS)
$(BUILD_DIR)/engine: $(OBJS)
$(V) $(CC) -o $@ $^ $(CFLAGS) $(LIBS)
.PHONY: clean
clean:
rm -rf $(BUILD_DIR)

9
README.md
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@ -16,6 +16,13 @@ To best learn what a GPU is doing, I wanted to recreate the functionality
of the GPU in software. It's not anywhere near as fast as a GPU of course,
but it's not slow either (for a single model that is relatively low-poly).
### Simple code
Coming from a C background, I wanted to use features of C++ that I found made
the code cleaner and easier to understand while avoiding many of the fancier
ones that seemed unnecessary. Primarily I leveraged operator overloading for
vector and matrix operations, and used some simple classes with constructors.
### Good cache performance
The biggest bottleneck of modern CPU performance is latency between memory and
@ -30,5 +37,3 @@ understand how OBJ files are constructed, along with their respective MTL files.
I also wrote my own linear algebra functions and classes (rather than use `glm`)
to better understand the low-level math operations.
![Demo](https://austinmorlan.com/files/soft-3d-renderer/garrus.gif)

47
Source/Camera.hpp
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@ -1,47 +0,0 @@
#pragma once
#include "Engine.hpp"
#include "Point.hpp"
#include <cmath>
constexpr float DegToRad(float degrees)
{
return degrees * (float)M_PI / 180.0f;
}
class Camera
{
public:
Camera()
{
position.x = 0.0f;
position.y = 0.0f;
position.z = 0.0f;
rotation.x = 0.0f;
rotation.y = 0.0f;
rotation.z = 0.0f;
zClipBias0 =
(CAMERA_FAR_CLIP + CAMERA_NEAR_CLIP)
/ (CAMERA_FAR_CLIP - CAMERA_NEAR_CLIP);
zClipBias1 =
(-2.0f * CAMERA_FAR_CLIP * CAMERA_NEAR_CLIP)
/ (CAMERA_FAR_CLIP - CAMERA_NEAR_CLIP);
xZoom = 1.0f / tanf(DegToRad(CAMERA_FOV / 2.0f));
yZoom = (xZoom * WINDOW_WIDTH) / WINDOW_HEIGHT;
xScale = (0.5f * WINDOW_WIDTH) - 0.5f;
yScale = (0.5f * WINDOW_HEIGHT) - 0.5f;
}
Point position;
Point rotation;
float zClipBias0, zClipBias1;
float xZoom, yZoom;
float xScale, yScale;
};

116
Source/Color.hpp
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@ -1,116 +0,0 @@
#pragma once
#include <algorithm>
#include <cstdint>
class ColorU32
{
public:
ColorU32()
: b(0), g(0), r(0), a(0)
{}
ColorU32(uint8_t b, uint8_t g, uint8_t r, uint8_t a)
: b(b), g(g), r(r), a(a)
{}
union
{
struct
{
uint8_t b, g, r, a;
};
uint32_t u32;
};
};
class ColorF32
{
public:
ColorF32()
: b(0.0f), g(0.0f), r(0.0f), a(0.0f)
{}
ColorF32(float b, float g, float r, float a)
: b(b), g(g), r(r), a(a)
{}
void Scale()
{
float blue = std::max(b, 0.0f);
float green = std::max(g, 0.0f);
float red = std::max(r, 0.0f);
float alpha = std::max(a, 0.0f);
float max = std::max(std::max(std::max(blue, green), red), 1.0f);
ColorF32 scaled(blue, green, red, alpha);
scaled /= max;
b = scaled.b;
g = scaled.g;
r = scaled.r;
a = scaled.a;
}
float b, g, r, a;
ColorF32 operator+(ColorF32 const& rhs) const
{
return ColorF32(
b + rhs.b,
g + rhs.g,
r + rhs.r,
a + rhs.a);
}
ColorF32& operator+=(ColorF32 const& rhs)
{
b += rhs.b;
g += rhs.g;
r += rhs.r;
a += rhs.a;
return *this;
}
ColorF32 operator*(float f) const
{
return ColorF32(
b * f,
g * f,
r * f,
a * f);
}
ColorF32 operator*(ColorF32 const& rhs) const
{
return ColorF32(
b * rhs.b,
g * rhs.g,
r * rhs.r,
a * rhs.a);
}
ColorF32 operator/(float f) const
{
float fInv = 1.0f / f;
return ColorF32(
b * fInv,
g * fInv,
r * fInv,
a * fInv);
}
ColorF32& operator/=(float f)
{
b /= f;
g /= f;
r /= f;
a /= f;
return *this;
}
};

345
Source/Engine.cpp
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@ -1,345 +0,0 @@
#include "Camera.hpp"
#include "Color.hpp"
#include "Engine.hpp"
#include "Geometry.hpp"
#include "Light.hpp"
#include "Loader.hpp"
#include "Matrix.hpp"
#include "Render.hpp"
#include "Transform.hpp"
#include "Vec.hpp"
#include <cstring>
#include <cstdio>
unsigned long constexpr CheckBit(uint32_t x, unsigned long bit)
{
return x & (1UL << bit);
}
static Mesh mesh;
static Camera camera;
static Light light;
static Matrix tPersp;
static Matrix tScreen;
static EngineMemory memory;
static void ComputeNormals();
static void CheckInputs(uint32_t input);
static void ClearDepthBuffer();
static void TransformToClipSpace();
static void ClipAndCull();
static void TransformToScreenSpace();
static void LightMesh();
int EngineInit(char* objFilename, char* mtlFilename)
{
int result;
result = ParseOBJ(objFilename, memory);
if (result < 0)
{
return -1;
}
result = ParseMTL(mtlFilename, memory);
if (result < 0)
{
return -1;
}
printf("Verts: %lu\n", memory.localVerts.size);
printf("Faces: %lu\n", memory.localFaces.size);
printf("Materials: %lu\n", memory.materials.size);
memory.transVerts.size = memory.localVerts.size;
// Compute vertex and face normals for lighting calculation
ComputeNormals();
// Mesh configuration
mesh.position.z = 200;
mesh.position.y = -100;
mesh.scale = 1.0f;
// Light configuration
light.position = Point(-300.0f, 200.0f, 0.0f);
light.color = ColorF32(1.0f, 1.0f, 1.0f, 1.0f);
light.intensity = 2.0f;
light.falloffConstant = 1.0f;
light.falloffLinear = 0.001f;
// Transformation matrices that do not change
tPersp = Transform_Perspective(camera);
tScreen = Transform_Screen(camera);
return 0;
}
void EngineRender(EngineBuffer& buffer, uint32_t input)
{
// Check for user input
CheckInputs(input);
// Clear the z-buffer
ClearDepthBuffer();
// Transform vertices to clip space
TransformToClipSpace();
// Clip near/far Z and cull backfaces
ClipAndCull();
// Light vertices and/or faces
LightMesh();
// Transform vertices to screen space
TransformToScreenSpace();
// Render
Render(buffer, memory);
}
void EngineShutdown()
{
}
// PRIVATE FUNCTIONS
static void CheckInputs(uint32_t input)
{
if (CheckBit(input, TRANSLATE_X_POS))
{
light.position.x += 10;
}
else if (CheckBit(input, TRANSLATE_X_NEG))
{
light.position.x -= 10;
}
if (CheckBit(input, TRANSLATE_Z_POS))
{
light.position.z += 10;
}
else if (CheckBit(input, TRANSLATE_Z_NEG))
{
light.position.z -= 10;
}
if (CheckBit(input, TRANSLATE_Y_POS))
{
light.position.y += 10;
}
else if (CheckBit(input, TRANSLATE_Y_NEG))
{
light.position.y -= 10;
}
if (CheckBit(input, ROTATE_X_POS))
{
mesh.rotation.x += 0.10f;
}
else if (CheckBit(input, ROTATE_X_NEG))
{
mesh.rotation.x -= 0.10f;
}
if (CheckBit(input, ROTATE_Y_POS))
{
mesh.rotation.y += 0.10f;
}
else if (CheckBit(input, ROTATE_Y_NEG))
{
mesh.rotation.y -= 0.10f;
}
if (CheckBit(input, ROTATE_Z_POS))
{
mesh.rotation.z += 0.10f;
}
else if (CheckBit(input, ROTATE_Z_NEG))
{
mesh.rotation.z -= 0.10f;
}
if (CheckBit(input, SCALE_UP))
{
light.color.b = 0.0f;
light.color.g = 0.0f;
light.color.r = 1.0f;
}
else if (CheckBit(input, SCALE_DOWN))
{
light.color.b = 1.0f;
light.color.g = 1.0f;
light.color.r = 1.0f;
}
}
static void ComputeNormals()
{
VertexList& verts = memory.localVerts;
FaceList& faces = memory.localFaces;
int vertexNormalCount[VERTEX_LIMIT] = {};
for (size_t f = 0; f < faces.size; ++f)
{
Face& face = faces.data[f];
Vertex& vert0 = verts.data[face.vertIndex[0]];
Vertex& vert1 = verts.data[face.vertIndex[1]];
Vertex& vert2 = verts.data[face.vertIndex[2]];
Vector v01 = vert1.position - vert0.position;
Vector v02 = vert2.position - vert0.position;
Vector normal = Vector::Cross(v01, v02);
// Add each vertex's normal to the sum for future averaging
vert0.normal += normal;
vert1.normal += normal;
vert2.normal += normal;
++vertexNormalCount[face.vertIndex[0]];
++vertexNormalCount[face.vertIndex[1]];
++vertexNormalCount[face.vertIndex[2]];
}
for (size_t v = 0; v < verts.size; ++v)
{
if (vertexNormalCount[v] > 0)
{
// Compute the average normal for this vertex
verts.data[v].normal /= static_cast<float>(vertexNormalCount[v]);
verts.data[v].normal.Normalize();
}
}
}
static void ClearDepthBuffer()
{
memset(memory.zbuffer, 0, sizeof(memory.zbuffer));
}
static void TransformToClipSpace()
{
VertexList& localVerts = memory.localVerts;
VertexList& transVerts = memory.transVerts;
Matrix tTranslate = Transform_Translate(mesh.position);
Matrix tRotate = Transform_Rotate(mesh.rotation);
Matrix tScale = Transform_Scale(mesh.scale);
Matrix tView = Transform_View(camera);
for (size_t v = 0; v < localVerts.size; ++v)
{
transVerts.data[v].position =
localVerts.data[v].position * tScale * tRotate * tTranslate * tView * tPersp;
transVerts.data[v].normal =
localVerts.data[v].normal * tScale * tRotate * tTranslate;
}
}
void ClipAndCull()
{
FaceList& localFaces = memory.localFaces;
FaceList& transFaces = memory.transFaces;
VertexList& verts = memory.transVerts;
int faceIndex = 0;
for (size_t f = 0; f < localFaces.size; ++f)
{
Face& face = localFaces.data[f];
Point& p0 = verts.data[face.vertIndex[0]].position;
Point& p1 = verts.data[face.vertIndex[1]].position;
Point& p2 = verts.data[face.vertIndex[2]].position;
// Ignore this face if its Z is outside the Z clip planes
if ((p0.z < -p0.w)
|| (p0.z > p0.w)
|| (p1.z < -p1.w)
|| (p1.z > p1.w)
|| (p2.z < -p2.w)
|| (p2.z > p2.w))
{
continue;
}
// Calculate the face's normal (inverted for Blender-compatibility)
Vector v01 = p1 - p0;
Vector v02 = p2 - p0;
Vector normal = -Vector::Cross(v01, v02);
// Eye vector to viewport
Vector view = camera.position - p0;
float dot = Vector::Dot(normal, view);
// Not a backface; add it to the list
if (dot < 0.0f)
{
transFaces.data[faceIndex] = face;
++faceIndex;
transFaces.size = (size_t)faceIndex;
}
}
}
static void TransformToScreenSpace()
{
VertexList& verts = memory.transVerts;
for (size_t v = 0; v < verts.size; ++v)
{
verts.data[v].position *= tScreen;
verts.data[v].position.x /= verts.data[v].position.w;
verts.data[v].position.y /= verts.data[v].position.w;
verts.data[v].position.z /= verts.data[v].position.w;
}
}
static void LightMesh()
{
VertexList& verts = memory.transVerts;
FaceList& faces = memory.transFaces;
MaterialList& materials = memory.materials;
for (size_t f = 0; f < faces.size; ++f)
{
Face& face = faces.data[f];
Material& material = materials.data[face.materialIndex];
// Gouraud shading
for (auto index : face.vertIndex)
{
Vertex& vert = verts.data[index];
vert.color = light.Compute(vert.position, vert.normal, material, camera);
}
}
}

55
Source/Engine.hpp
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@ -1,55 +0,0 @@
#pragma once
#include "Geometry.hpp"
#include <cstdint>
const int WINDOW_WIDTH = 1920;
const int WINDOW_HEIGHT = 1080;
const int WINDOW_FPS = 30;
const float CAMERA_FOV = 90.0f;
const float CAMERA_NEAR_CLIP = 5.0f;
const float CAMERA_FAR_CLIP = 600.0f;
enum EngineInput
{
TRANSLATE_X_POS,
TRANSLATE_X_NEG,
TRANSLATE_Y_POS,
TRANSLATE_Y_NEG,
TRANSLATE_Z_POS,
TRANSLATE_Z_NEG,
ROTATE_X_POS,
ROTATE_X_NEG,
ROTATE_Y_POS,
ROTATE_Y_NEG,
ROTATE_Z_POS,
ROTATE_Z_NEG,
SCALE_UP,
SCALE_DOWN
};
struct EngineBuffer
{
uint32_t* buffer;
int width;
int height;
};
struct EngineMemory
{
float zbuffer[WINDOW_HEIGHT][WINDOW_WIDTH];
VertexList localVerts;
VertexList transVerts;
FaceList localFaces;
FaceList transFaces;
UVList uvs;
MaterialList materials;
TextureList textures;
};
int EngineInit(char* objFilename, char* mtlFilename);
void EngineRender(EngineBuffer& buffer, uint32_t input);
void EngineShutdown();

85
Source/Geometry.hpp
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@ -1,85 +0,0 @@
#pragma once
#include "Color.hpp"
#include "Point.hpp"
#include "Vec.hpp"
#include <cstdint>
const int FACE_LIMIT = 30000;
const int MATERIAL_LIMIT = 5;
const int TEXTURE_SIZE_LIMIT = 1024;
const int VERTEX_LIMIT = 20000;
struct Texture
{
ColorU32 texels[TEXTURE_SIZE_LIMIT][TEXTURE_SIZE_LIMIT];
unsigned int width;
unsigned int height;
};
struct TextureList
{
Texture data[MATERIAL_LIMIT];
};
struct Material
{
ColorF32 ambient;
ColorF32 diffuse;
ColorF32 specular;
float glossiness;
float opacity;
};
struct MaterialList
{
Material data[MATERIAL_LIMIT];
unsigned long size;
};
struct UV
{
float u;
float v;
};
struct UVList
{
UV data[VERTEX_LIMIT];
unsigned long size;
};
struct Vertex
{
Point position;
Vector normal;
ColorF32 color;
};
struct VertexList
{
Vertex data[VERTEX_LIMIT];
unsigned long size;
};
struct Face
{
int vertIndex[3];
int uvIndex[3];
int materialIndex;
};
struct FaceList
{
Face data[FACE_LIMIT];
unsigned long size;
};
struct Mesh
{
Point position;
Point rotation;
float scale;
};

58
Source/Light.hpp
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@ -1,58 +0,0 @@
#pragma once
#include "Camera.hpp"
#include "Color.hpp"
#include "Geometry.hpp"
#include "Point.hpp"
class Light
{
public:
ColorF32 Compute(Point& eye, Vector& normal, Material& material, Camera& camera)
{
// Point light intensity is a function of the falloff factors and the distance
Vector direction = position - eye;
direction.Normalize();
float distance = direction.Length();
ColorF32 totalIntensity =
(color * intensity)
/ (falloffConstant + (falloffLinear * distance));
// Diffuse Light = Kr * I * (alpha + (1 - alpha) * n.d)
float dotNormalDirection = std::max(Vector::Dot(normal, direction), 0.0f);
float alpha = 0.2f;
ColorF32 diffuseLight =
material.diffuse
* totalIntensity
* (alpha + (1.0f - alpha) * dotNormalDirection);
// Specular Light = Ks * I * (r.v)^sp
Vector view = camera.position - eye;
view.Normalize();
Vector reflection = (normal * 2.0f * dotNormalDirection) - direction;
float dotReflectionView = std::max(Vector::Dot(reflection, view), 0.0f);
ColorF32 specularLight =
material.specular
* totalIntensity
* powf(dotReflectionView, material.glossiness);
// Total light is sum of all lights
ColorF32 result = diffuseLight + specularLight;
return result;
}
Point position;
ColorF32 color;
float intensity;
float falloffConstant;
float falloffLinear;
};

256
Source/Loader.cpp
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@ -1,256 +0,0 @@
#include "Engine.hpp"
#include "Loader.hpp"
#include <cctype>
#include <cstdio>
#include <cstdint>
#include <cstdlib>
#include <cstring>
static int LoadTexture(char* filename, Texture& texture, float opacity);
#pragma pack(push, 1)
struct BMP_Header
{
uint16_t fileType;
uint32_t fileSize;
uint16_t reserved0;
uint16_t reserved1;
uint32_t bitmapOffset;
uint32_t size;
int32_t width;
int32_t height;
uint16_t planes;
uint16_t bitsPerPixel;
uint32_t compression;
uint32_t sizeOfBitmap;
int32_t horizRes;
int32_t vertRes;
uint32_t colorsUsed;
uint32_t colorsImportant;
};
#pragma pack(pop)
int ParseOBJ(char* filename, EngineMemory& memory)
{
FILE* fp = fopen(filename, "r");
if (fp == nullptr)
{
fprintf(stderr, "Error loading file: %s\n", filename);
return -1;
}
char line[256];
unsigned long vertIndex = 0;
unsigned long uvIndex = 0;
unsigned long faceIndex = 0;
int materialIndex = -1;
VertexList& verts = memory.localVerts;
FaceList& faces = memory.localFaces;
UVList& uvs = memory.uvs;
while (fgets(line, sizeof(line), fp))
{
char* separator = strchr(line, ' ');
if (separator != nullptr)
{
*separator = '\0';
char* type = line;
char* data = separator + 1;
if (strcmp(type, "v") == 0)
{
sscanf(
data, "%f %f %f",
&verts.data[vertIndex].position.x,
&verts.data[vertIndex].position.y,
&verts.data[vertIndex].position.z);
verts.data[vertIndex].position.w = 1.0f;
++vertIndex;
}
else if (strcmp(type, "vt") == 0)
{
sscanf(
data, "%f %f",
&uvs.data[uvIndex].u,
&uvs.data[uvIndex].v);
++uvIndex;
}
else if (strcmp(type, "usemtl") == 0)
{
++materialIndex;
}
else if (strcmp(type, "f") == 0)
{
sscanf(
data, "%d/%d %d/%d %d/%d",
&faces.data[faceIndex].vertIndex[0],
&faces.data[faceIndex].uvIndex[0],
&faces.data[faceIndex].vertIndex[1],
&faces.data[faceIndex].uvIndex[1],
&faces.data[faceIndex].vertIndex[2],
&faces.data[faceIndex].uvIndex[2]);
// Convert to 0-indexed
faces.data[faceIndex].vertIndex[0] -= 1;
faces.data[faceIndex].vertIndex[1] -= 1;
faces.data[faceIndex].vertIndex[2] -= 1;
faces.data[faceIndex].uvIndex[0] -= 1;
faces.data[faceIndex].uvIndex[1] -= 1;
faces.data[faceIndex].uvIndex[2] -= 1;
faces.data[faceIndex].materialIndex = materialIndex;
++faceIndex;
}
}
}
verts.size = vertIndex;
uvs.size = uvIndex;
faces.size = faceIndex;
return 0;
}
int ParseMTL(char* filename, EngineMemory& memory)
{
FILE* fp = fopen(filename, "r");
if (fp == nullptr)
{
fprintf(stderr, "Error loading file: %s\n", filename);
return -1;
}
char line[256];
int materialIndex = -1;
MaterialList& materials = memory.materials;
TextureList& textures = memory.textures;
while (fgets(line, sizeof(line), fp))
{
char* separator = strchr(line, ' ');
if (separator != nullptr)
{
*separator = '\0';
char* type = line;
char* data = separator + 1;
if (strcmp(type, "newmtl") == 0)
{
++materialIndex;
}
else if (strcmp(type, "Ns") == 0)
{
sscanf(
data, "%f",
&materials.data[materialIndex].glossiness);
}
else if (strcmp(type, "Ka") == 0)
{
sscanf(
data, "%f %f %f",
&materials.data[materialIndex].ambient.r,
&materials.data[materialIndex].ambient.g,
&materials.data[materialIndex].ambient.b);
}
else if (strcmp(type, "Kd") == 0)
{
sscanf(
data, "%f %f %f",
&materials.data[materialIndex].diffuse.r,
&materials.data[materialIndex].diffuse.g,
&materials.data[materialIndex].diffuse.b);
}
else if (strcmp(type, "Ks") == 0)
{
sscanf(
data, "%f %f %f",
&materials.data[materialIndex].specular.r,
&materials.data[materialIndex].specular.g,
&materials.data[materialIndex].specular.b);
}
else if (strcmp(type, "d") == 0)
{
sscanf(
data, "%f",
&materials.data[materialIndex].opacity);
}
else if (strcmp(type, "map_Kd") == 0)
{
char* textureFilename = data;
textureFilename[strcspn(textureFilename, "\r\n")] = 0;
LoadTexture(
textureFilename, textures.data[materialIndex],
materials.data[materialIndex].opacity);
}
}
}
materials.size = materialIndex + 1;
return 0;
}
static int LoadTexture(char* filename, Texture& texture, float opacity)
{
FILE* fp = fopen(filename, "r");
if (fp == nullptr)
{
fprintf(stderr, "Could not open file: %s\n", filename);
return -1;
}
BMP_Header header = {};
fread((void*)&header, sizeof(BMP_Header), 1, fp);
fseek(fp, header.bitmapOffset, SEEK_SET);
// Padding is added to image to align to 4-byte boundaries
unsigned long paddingSize = static_cast<unsigned long>(header.width % 4);
for (int y = 0; y < header.height; ++y)
{
for (int x = 0; x < header.width; ++x)
{
fread(&texture.texels[y][x].b, 1, 1, fp);
fread(&texture.texels[y][x].g, 1, 1, fp);
fread(&texture.texels[y][x].r, 1, 1, fp);
texture.texels[y][x].a = (uint8_t)(255 * opacity);
}
// Discard padding byte
if (paddingSize != 0)
{
uint32_t padding;
fread(&padding, paddingSize, 1, fp);
}
}
texture.width = (unsigned int)header.width;
texture.height = (unsigned int)header.height;
fclose(fp);
return 0;
}

7
Source/Loader.hpp
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#pragma once
#include "Engine.hpp"
int ParseOBJ(char* filename, EngineMemory& memory);
int ParseMTL(char* filename, EngineMemory& memory);

60
Source/Main.cpp
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#include "Engine.hpp"
#include "Platform.hpp"
#include <cstdint>
#include <cstdio>
#include <cstdlib>
// MAIN
int main(int argc, char* argv[])
{
if (argc != 3)
{
fprintf(stderr, "Usage: %s <OBJ> <MTL>\n", argv[0]);
return EXIT_FAILURE;
}
char* objFilename = argv[1];
char* mtlFilename = argv[2];
Platform platform{};
if (Platform_Init(platform, WINDOW_WIDTH, WINDOW_HEIGHT) == PlatformStatus::Error)
{
return EXIT_FAILURE;
}
if (EngineInit(objFilename, mtlFilename) < 0)
{
return EXIT_FAILURE;
}
EngineBuffer buffer{};
buffer.buffer = reinterpret_cast<uint32_t*>(platform.surface->pixels);
buffer.width = platform.surface->w;
buffer.height = platform.surface->h;
while (true)
{
Platform_GetFrameTime(platform);
if (Platform_CheckForEvents(platform) == PlatformStatus::Quit)
{
break;
}
Platform_ClearWindow(platform);
EngineRender(buffer, platform.input);
Platform_UpdateWindow(platform);
Platform_SyncToFramerate(platform);
}
EngineShutdown();
Platform_Shutdown(platform);
return EXIT_SUCCESS;
}

49
Source/Matrix.hpp
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#pragma once
class Matrix
{
public:
Matrix()
{
e11 = 1.0; e12 = 0.0; e13 = 0.0; e14 = 0.0;
e21 = 0.0; e22 = 1.0; e23 = 0.0; e24 = 0.0;
e31 = 0.0; e32 = 0.0; e33 = 1.0; e34 = 0.0;
e41 = 0.0; e42 = 0.0; e43 = 0.0; e44 = 1.0;
}
union
{
float e[4][4];
struct
{
float e11, e12, e13, e14;
float e21, e22, e23, e24;
float e31, e32, e33, e34;
float e41, e42, e43, e44;
};
};
Matrix operator*(Matrix const& rhs)
{
Matrix result;
for (int row = 0; row < 4; ++row)
{
for (int col = 0; col < 4; ++col)
{
float sum = 0.0;
for (int i = 0; i < 4; ++i)
{
sum += e[row][i] * rhs.e[i][col];
}
result.e[row][col] = sum;
}
}
return result;
}
};

243
Source/Platform.cpp
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#include "Engine.hpp"
#include "Platform.hpp"
#include <cstdint>
#include <SDL2/SDL.h>
void constexpr SetBit(uint32_t& x, unsigned long bit)
{
x |= (1UL << bit);
}
void constexpr ClearBit(uint32_t& x, unsigned long bit)
{
x &= ~(1UL << bit);
}
static void HandleEvent(Platform& platform, SDL_Event& event);
PlatformStatus Platform_Init(Platform& platform, int width, int height)
{
int result = SDL_Init(SDL_INIT_VIDEO);
if (result < 0)
{
fprintf(stderr, "Error initializing SDL: %s\n", SDL_GetError());
return PlatformStatus::Error;
}
SDL_Window* window = SDL_CreateWindow(
"Soft 3D Engine",
SDL_WINDOWPOS_UNDEFINED, SDL_WINDOWPOS_UNDEFINED,
width, height,
SDL_WINDOW_SHOWN);
if (window == nullptr)
{
fprintf(stderr, "Error creating SDL window: %s\n", SDL_GetError());
return PlatformStatus::Error;
}
SDL_Surface* surface = SDL_GetWindowSurface(window);
if (surface == nullptr)
{
fprintf(stderr, "Error getting SDL window surface: %s\n", SDL_GetError());
return PlatformStatus::Error;
}
result = SDL_ShowCursor(SDL_DISABLE);
if (result < 0)
{
fprintf(stderr, "Error disabling cursor in SDL window: %s\n", SDL_GetError());
return PlatformStatus::Error;
}
platform.framerateMillis = (1000 / WINDOW_FPS);
platform.window = window;
platform.surface = surface;
return PlatformStatus::Ok;
}
PlatformStatus Platform_CheckForEvents(Platform& platform)
{
SDL_Event event;
while (SDL_PollEvent(&event) != 0)
{
if (event.type == SDL_QUIT)
{
return PlatformStatus::Quit;
}
else
{
HandleEvent(platform, event);
}
}
return PlatformStatus::Ok;
}
void Platform_ClearWindow(Platform& platform)
{
SDL_LockSurface(platform.surface);
SDL_FillRect(platform.surface, nullptr, 0);
}
void Platform_UpdateWindow(Platform& platform)
{
SDL_UnlockSurface(platform.surface);
SDL_UpdateWindowSurface(platform.window);
}
void Platform_GetFrameTime(Platform& platform)
{
platform.frameStartMillis = SDL_GetTicks();
}
void Platform_SyncToFramerate(Platform& platform)
{
uint32_t stopTimeMillis = SDL_GetTicks();
uint32_t framerateMillis = stopTimeMillis - platform.frameStartMillis;
// Delay if time to spare
if (framerateMillis < platform.framerateMillis)
{
uint32_t delayMillis = platform.framerateMillis - framerateMillis;
SDL_Delay(delayMillis);
}
}
void Platform_Shutdown(Platform& platform)
{
SDL_DestroyWindow(platform.window);
SDL_Quit();
}
// PRIVATE FUNCTIONS
static void HandleEvent(
Platform& platform, SDL_Event& event)
{
if (event.type == SDL_KEYDOWN)
{
if (event.key.keysym.sym == SDLK_w)
{
SetBit(platform.input, TRANSLATE_Z_POS);
}
else if (event.key.keysym.sym == SDLK_s)
{
SetBit(platform.input, TRANSLATE_Z_NEG);
}
else if (event.key.keysym.sym == SDLK_a)
{
SetBit(platform.input, TRANSLATE_X_NEG);
}
else if (event.key.keysym.sym == SDLK_d)
{
SetBit(platform.input, TRANSLATE_X_POS);
}
else if (event.key.keysym.sym == SDLK_q)
{
SetBit(platform.input, TRANSLATE_Y_POS);
}
else if (event.key.keysym.sym == SDLK_e)
{
SetBit(platform.input, TRANSLATE_Y_NEG);
}
else if (event.key.keysym.sym == SDLK_i)
{
SetBit(platform.input, ROTATE_X_POS);
}
else if (event.key.keysym.sym == SDLK_k)
{
SetBit(platform.input, ROTATE_X_NEG);
}
else if (event.key.keysym.sym == SDLK_j)
{
SetBit(platform.input, ROTATE_Y_POS);
}
else if (event.key.keysym.sym == SDLK_l)
{
SetBit(platform.input, ROTATE_Y_NEG);
}
else if (event.key.keysym.sym == SDLK_u)
{
SetBit(platform.input, ROTATE_Z_POS);
}
else if (event.key.keysym.sym == SDLK_o)
{
SetBit(platform.input, ROTATE_Z_NEG);
}
else if (event.key.keysym.sym == SDLK_UP)
{
SetBit(platform.input, SCALE_UP);
}
else if (event.key.keysym.sym == SDLK_DOWN)
{
SetBit(platform.input, SCALE_DOWN);
}
}
else if (event.type == SDL_KEYUP)
{
if (event.key.keysym.sym == SDLK_w)
{
ClearBit(platform.input, TRANSLATE_Z_POS);
}
else if (event.key.keysym.sym == SDLK_s)
{
ClearBit(platform.input, TRANSLATE_Z_NEG);
}
else if (event.key.keysym.sym == SDLK_a)
{
ClearBit(platform.input, TRANSLATE_X_NEG);
}
else if (event.key.keysym.sym == SDLK_d)
{
ClearBit(platform.input, TRANSLATE_X_POS);
}
else if (event.key.keysym.sym == SDLK_q)
{
ClearBit(platform.input, TRANSLATE_Y_POS);
}
else if (event.key.keysym.sym == SDLK_e)
{
ClearBit(platform.input, TRANSLATE_Y_NEG);
}
else if (event.key.keysym.sym == SDLK_i)
{
ClearBit(platform.input, ROTATE_X_POS);
}
else if (event.key.keysym.sym == SDLK_k)
{
ClearBit(platform.input, ROTATE_X_NEG);
}
else if (event.key.keysym.sym == SDLK_j)
{
ClearBit(platform.input, ROTATE_Y_POS);
}
else if (event.key.keysym.sym == SDLK_l)
{
ClearBit(platform.input, ROTATE_Y_NEG);
}
else if (event.key.keysym.sym == SDLK_u)
{
ClearBit(platform.input, ROTATE_Z_POS);
}
else if (event.key.keysym.sym == SDLK_o)
{
ClearBit(platform.input, ROTATE_Z_NEG);
}
else if (event.key.keysym.sym == SDLK_UP)
{
ClearBit(platform.input, SCALE_UP);
}
else if (event.key.keysym.sym == SDLK_DOWN)
{
ClearBit(platform.input, SCALE_DOWN);
}
}
}

38
Source/Platform.hpp
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#pragma once
#include <SDL2/SDL.h>
enum class PlatformStatus
{
Error = -1,
Ok,
Quit
};
// STRUCTURES
struct Platform
{
SDL_Window* window;
SDL_Surface* surface;
uint32_t input;
uint32_t framerateMillis;
uint32_t frameStartMillis;
};
// FUNCTIONS
PlatformStatus Platform_Init(Platform& platform, int width, int height);
PlatformStatus Platform_CheckForEvents(Platform& platform);
void Platform_ClearWindow(Platform& platform);
void Platform_UpdateWindow(Platform& platform);
void Platform_GetFrameTime(Platform& platform);
void Platform_SyncToFramerate(Platform& platform);
void Platform_Shutdown(Platform& platform);

88
Source/Point.hpp
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#pragma once
#include "Matrix.hpp"
#include "Vec.hpp"
class Point
{
public:
Point()
: x(0), y(0), z(0), w(1)
{}
Point(float x, float y, float z)
: x(x), y(y), z(z), w(1)
{}
Point operator-() const
{
return Point(
-x,
-y,
-z);
}
Vector operator-(Point const& rhs) const
{
return Vector(
x - rhs.x,
y - rhs.y,
z - rhs.z);
}
Point operator*(Matrix const& rhs)
{
Point result;
for (int col = 0; col < 4; ++col)
{
float sum = 0.0;
for (int row = 0; row < 4; ++row)
{
sum += e[row] * rhs.e[row][col];
}
result.e[col] = sum;
}
return result;
}
Point& operator*=(Matrix const& rhs)
{
*this = *this * rhs;
return *this;
}
Point operator/(float rhs) const
{
float inverse = 1.0f / rhs;
return Point(
x * inverse,
y * inverse,
z * inverse);
}
Point& operator/=(float rhs)
{
x /= rhs;
y /= rhs;
z /= rhs;
return *this;
}
union
{
float e[4];
struct
{
float x, y, z, w;
};
};
};

199
Source/Render.cpp
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#include "Color.hpp"
#include "Engine.hpp"
#include "Geometry.hpp"
#include "Render.hpp"
class BoundingBox
{
public:
BoundingBox(Point const& v0, Point const& v1, Point const& v2)
{
yMin = std::min(v0.y, std::min(v1.y, v2.y));
yMax = std::max(v0.y, std::max(v1.y, v2.y));
xMin = std::min(v0.x, std::min(v1.x, v2.x));
xMax = std::max(v0.x, std::max(v1.x, v2.x));
}
float yMin, yMax;
float xMin, xMax;
};
void Render(EngineBuffer& buffer, EngineMemory& memory)
{
FaceList const& faces = memory.transFaces;
VertexList const& verts = memory.transVerts;
TextureList const& textures = memory.textures;
UVList const& uvs = memory.uvs;
for (size_t f = 0; f < faces.size; ++f)
{
Face const& face = faces.data[f];
Point const& p0 = verts.data[face.vertIndex[0]].position;
Point const& p1 = verts.data[face.vertIndex[1]].position;
Point const& p2 = verts.data[face.vertIndex[2]].position;
// Bounding box for barycentric calculations (top-left fill convention)
BoundingBox box(p0, p1, p2);
int yMin = static_cast<int>(std::max<float>(ceilf(box.yMin), 0));
int yMax = static_cast<int>(std::min<float>(ceilf(box.yMax) - 1, buffer.height - 1));
int xMin = static_cast<int>(std::max<float>(ceilf(box.xMin), 0));
int xMax = static_cast<int>(std::min<float>(ceilf(box.xMax) - 1, buffer.width - 1));
// Constants for this triangle used for barycentric calculations
Vector v01 = p1 - p0;
Vector v02 = p2 - p0;
float dot0101 = Vector::Dot(v01, v01);
float dot0102 = Vector::Dot(v01, v02);
float dot0202 = Vector::Dot(v02, v02);
// Iterate over the bounding box and determine if each point is in the triangle
for (int y = yMin; y <= yMax; ++y)
{
for (int x = xMin; x <= xMax; ++x)
{
// Calculate the barycentric coordinate of this point
Point p(x, y, 1.0f);
Vector v0P = p - p0;
float dot0P01 = Vector::Dot(v0P, v01);
float dot0P02 = Vector::Dot(v0P, v02);
float denomInv = 1.0f / ((dot0101 * dot0202) - (dot0102 * dot0102));
float barycenter[3];
barycenter[1] = (dot0202 * dot0P01 - dot0102 * dot0P02) * denomInv;
barycenter[2] = (dot0101 * dot0P02 - dot0102 * dot0P01) * denomInv;
barycenter[0] = 1.0f - barycenter[1] - barycenter[2];
// Point is inside the triangle
if ((barycenter[0] >= 0.0f)
&& (barycenter[1] >= 0.0f)
&& (barycenter[2] >= 0.0f))
{
// Interpolate 1/z for the z-buffer
float zInv =
1.0f /
((barycenter[0] * p0.w)
+ (barycenter[1] * p1.w)
+ (barycenter[2] * p2.w));
// Compute pixel color if it's closer than what's in the z-buffer
if (zInv > memory.zbuffer[y][x])
{
// Update the depth buffer
memory.zbuffer[y][x] = zInv;
// Interpolate U and V of the texture for this point
Texture const& texture = textures.data[faces.data[f].materialIndex];
UV const& uv0 = uvs.data[face.uvIndex[0]];
UV const& uv1 = uvs.data[face.uvIndex[1]];
UV const& uv2 = uvs.data[face.uvIndex[2]];
float a = barycenter[0] * p1.w * p2.w;
float b = barycenter[1] * p0.w * p2.w;
float c = barycenter[2] * p0.w * p1.w;
float abc = 1.0f / (a + b + c);
float uInterp =
((a * uv0.u) + (b * uv1.u) + (c * uv2.u))
* abc
* texture.width;
float vInterp =
((a * uv0.v) + (b * uv1.v) + (c * uv2.v))
* abc
* texture.height;
// Bilinear filtering
unsigned int u = static_cast<unsigned int>(uInterp);
unsigned int v = static_cast<unsigned int>(vInterp);
float du = uInterp - u;
float dv = vInterp - v;
float duDiff = 1 - du;
float dvDiff = 1 - dv;
ColorU32 color(
static_cast<uint8_t>(
(duDiff * dvDiff * texture.texels[v][u].b
+ du * dvDiff * texture.texels[v][u + 1].b
+ du * dv * texture.texels[v + 1][u + 1].b
+ duDiff * dv * texture.texels[v + 1][u].b)),
static_cast<uint8_t>(
(duDiff * dvDiff * texture.texels[v][u].g
+ du * dvDiff * texture.texels[v][u + 1].g
+ du * dv * texture.texels[v + 1][u + 1].g
+ duDiff * dv * texture.texels[v + 1][u].g)),
static_cast<uint8_t>(
(duDiff * dvDiff * texture.texels[v][u].r
+ du * dvDiff * texture.texels[v][u + 1].r
+ du * dv * texture.texels[v + 1][u + 1].r
+ duDiff * dv * texture.texels[v + 1][u].r)),
static_cast<uint8_t>(
(duDiff * dvDiff * texture.texels[v][u].a
+ du * dvDiff * texture.texels[v][u + 1].a
+ du * dv * texture.texels[v + 1][u + 1].a
+ duDiff * dv * texture.texels[v + 1][u].a)));
// Perform Gouraud shading on the texture
ColorF32 const& c0 = verts.data[face.vertIndex[0]].color;
ColorF32 const& c1 = verts.data[face.vertIndex[1]].color;
ColorF32 const& c2 = verts.data[face.vertIndex[2]].color;
ColorF32 shading =
(c0 * barycenter[0])
+ (c1 * barycenter[1])
+ (c2 * barycenter[2]);
// Ensure no color channel exceeds max
shading.Scale();
// Light the texture
color.b *= shading.b;
color.g *= shading.g;
color.r *= shading.r;
// Alpha blend the pixel
ColorU32* pixel = reinterpret_cast<ColorU32*>(&buffer.buffer[y * buffer.width + x]);
float alpha = static_cast<float>(color.a) / 255.0f;
float alphaDiff = 1.0f - alpha;
ColorU32 blended =
{
static_cast<uint8_t>(((alpha * static_cast<float>(color.b)) +
(alphaDiff * static_cast<float>(pixel->b)))),
static_cast<uint8_t>(((alpha * static_cast<float>(color.g)) +
(alphaDiff * static_cast<float>(pixel->g)))),
static_cast<uint8_t>(((alpha * static_cast<float>(color.r)) +
(alphaDiff * static_cast<float>(pixel->r)))),
static_cast<uint8_t>(((alpha * static_cast<float>(color.a)) +
(alphaDiff * static_cast<float>(pixel->a))))
};
// Draw
buffer.buffer[buffer.width * y + x] = blended.u32;
}
}
}
}
}
}

6
Source/Render.hpp
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#pragma once
#include "Engine.hpp"
void Render(EngineBuffer& buffer, EngineMemory& memory);

105
Source/Transform.cpp
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#include "Matrix.hpp"
#include "Transform.hpp"
#include <cmath>
Matrix Transform_Translate(Point& translation)
{
Matrix result;
result.e41 = translation.x;
result.e42 = translation.y;
result.e43 = translation.z;
return result;
}
Matrix Transform_Rotate(Point& rotation)
{
// YXZ Euler rotation
float cosThetaY = cosf(rotation.y);
float sinThetaY = sinf(rotation.y);
Matrix tRotateY;
tRotateY.e11 = cosThetaY;
tRotateY.e13 = -sinThetaY;
tRotateY.e31 = sinThetaY;
tRotateY.e33 = cosThetaY;
float cosThetaX = cosf(rotation.x);
float sinThetaX = sinf(rotation.x);
Matrix tRotateX;
tRotateX.e22 = cosThetaX;
tRotateX.e23 = sinThetaX;
tRotateX.e32 = -sinThetaX;
tRotateX.e33 = cosThetaX;
float cosThetaZ = cosf(rotation.z);
float sinThetaZ = sinf(rotation.z);
Matrix tRotateZ;
tRotateZ.e11 = cosThetaZ;
tRotateZ.e12 = sinThetaZ;
tRotateZ.e21 = -sinThetaZ;
tRotateZ.e22 = cosThetaZ;
Matrix result = tRotateY * tRotateX * tRotateZ;
return result;
}
Matrix Transform_Scale(float scale)
{
Matrix result;
result.e11 = scale;
result.e22 = scale;
result.e33 = scale;
return result;
}
Matrix Transform_View(Camera& camera)
{
Point invPosition = -camera.position;
Matrix tInvTranslate = Transform_Translate(invPosition);
Point invRotation = -camera.rotation;
Matrix tInvRotate = Transform_Rotate(invRotation);
Matrix result = tInvTranslate * tInvRotate;
return result;
}
Matrix Transform_Perspective(Camera& camera)
{
Matrix result;
result.e11 = camera.xZoom;
result.e22 = camera.yZoom;
result.e33 = camera.zClipBias0;
result.e34 = 1;
result.e43 = camera.zClipBias1;
return result;
}
Matrix Transform_Screen(Camera& camera)
{
Matrix result;
result.e11 = camera.xScale;
result.e41 = camera.xScale;
result.e22 = -camera.yScale;
result.e42 = camera.yScale;
return result;
}

12
Source/Transform.hpp
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#pragma once
#include "Camera.hpp"
#include "Matrix.hpp"
Matrix Transform_Translate(Point& translation);
Matrix Transform_Rotate(Point& rotation);
Matrix Transform_Scale(float scale);
Matrix Transform_View(Camera& camera);
Matrix Transform_Perspective(Camera& camera);
Matrix Transform_Screen(Camera& camera);

159
Source/Vec.hpp
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#pragma once
#include "Matrix.hpp"
#include <algorithm>
#include <cmath>
class Vector
{
public:
Vector()
: x(0), y(0), z(0), w(0)
{}
Vector(float x, float y, float z)
: x(x), y(y), z(z), w(0)
{}
Vector operator-() const
{
return Vector(
-x,
-y,
-z);
}
Vector operator-(Vector const& rhs) const
{
return Vector(
x - rhs.x,
y - rhs.y,
z - rhs.z);
}
Vector operator+(Vector const& rhs) const
{
return Vector(
x + rhs.x,
y + rhs.y,
z + rhs.z);
}
Vector& operator+=(Vector const& rhs)
{
x += rhs.x;
y += rhs.y;
z += rhs.z;
return *this;
}
Vector operator*(float rhs) const
{
return Vector(
x * rhs,
y * rhs,
z * rhs);
}
Vector operator*(Matrix const& rhs)
{
Vector result;
for (int col = 0; col < 4; ++col)
{
float sum = 0.0;
for (int row = 0; row < 4; ++row)
{
sum += e[row] * rhs.e[row][col];
}
result.e[col] = sum;
}
return result;
}
Vector operator/(float rhs) const
{
float inverse = 1.0f / rhs;
return Vector(
x * inverse,
y * inverse,
z * inverse);
}
Vector& operator/=(float rhs)
{
x /= rhs;
y /= rhs;
z /= rhs;
return *this;
}
float Length()
{
float result = sqrtf(x * x + y * y + z * z);
if (result < 0.0f)
{
result = 0.0f;
}
return result;
}
void Normalize()
{
float length = Length();
if (length == 0.0f)
{
x = 0.0f;
y = 0.0f;
z = 0.0f;
}
else
{
float lengthInv = 1.0f / length;
x *= lengthInv;
y *= lengthInv;
z *= lengthInv;
}
}
static Vector Cross(Vector& v1, Vector& v2)
{
Vector result;
result.x = (v1.y * v2.z) - (v1.z * v2.y);
result.y = (v1.z * v2.x) - (v1.x * v2.z);
result.z = (v1.x * v2.y) - (v1.y * v2.x);
return result;
}
static float Dot(Vector& v1, Vector& v2)
{
float result;
result = (v1.x * v2.x) + (v1.y * v2.y) + (v1.z * v2.z);
return result;
}
union
{
float e[4];
struct
{
float x, y, z, w;
};
};
};

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#ifndef CAMERA_H
#include "engine.h"
#include "point.h"
#include "util.h"
#include <cmath>
// STRUCTURE
struct Camera
{
inline Camera(void)
{
position.x = 0.0f;
position.y = 0.0f;
position.z = 0.0f;
rotation.x = 0.0f;
rotation.y = 0.0f;
rotation.z = 0.0f;
zClipBias0 =
(CAMERA_FAR_CLIP + CAMERA_NEAR_CLIP)
/ (CAMERA_FAR_CLIP - CAMERA_NEAR_CLIP);
zClipBias1 =
(-2.0f * CAMERA_FAR_CLIP * CAMERA_NEAR_CLIP)
/ (CAMERA_FAR_CLIP - CAMERA_NEAR_CLIP);
xZoom = 1.0f / tanf(DEG_TO_RAD(CAMERA_FOV/2.0f));
yZoom = (xZoom * WINDOW_WIDTH) / WINDOW_HEIGHT;
xScale = (0.5f * WINDOW_WIDTH) - 0.5f;
yScale = (0.5f * WINDOW_HEIGHT) - 0.5f;
}
Point position;
Point rotation;
float zClipBias0, zClipBias1;
float xZoom, yZoom;
float xScale, yScale;
};
#define CAMERA_H
#endif

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#ifndef COLOR_H
#include "util.h"
#include <cstdint>
// STRUCTURES
struct ColorU32
{
union
{
struct
{
uint8_t b, g, r, a;
};
uint32_t u32;
};
};
struct ColorF32
{
float b, g, r, a;
};
// OPERATORS
// c1 + c2
inline ColorF32 operator+(ColorF32 const &c1, ColorF32 const &c2)
{
ColorF32 result;
result.b = c1.b + c2.b;
result.g = c1.g + c2.g;
result.r = c1.r + c2.r;
result.a = c1.a + c2.a;
return result;
}
// c1 += c2
inline ColorF32 &operator+=(ColorF32 &c1, ColorF32 const &c2)
{
c1 = c1 + c2;
return c1;
}
// c * f
inline ColorF32 operator*(ColorF32 const &c, float f)
{
ColorF32 result;
result.b = f * c.b;
result.g = f * c.g;
result.r = f * c.r;
result.a = f * c.a;
return result;
}
// f * c
inline ColorF32 operator*(float f, ColorF32 const &c)
{
ColorF32 result;
result = c * f;
return result;
}
// c1 * c2
inline ColorF32 operator*(ColorF32 const &c1, ColorF32 const &c2)
{
ColorF32 result;
result.b = c1.b * c2.b;
result.g = c1.g * c2.g;
result.r = c1.r * c2.r;
result.a = c1.a * c2.a;
return result;
}
// c / f
inline ColorF32 operator/(ColorF32 const &c, float f)
{
ColorF32 result;
float invF = 1.0f / f;
result.b = c.b * invF;
result.g = c.g * invF;
result.r = c.r * invF;
result.a = c.a * invF;
return result;
}
// c /= f
inline ColorF32 &operator/=(ColorF32 &c, float f)
{
c = c / f;
return c;
}
// PUBLIC FUNCTIONS
inline void ScaleColor(ColorF32 &c)
{
float blue = MAX(c.b, 0.0f);
float green = MAX(c.g, 0.0f);
float red = MAX(c.r, 0.0f);
float alpha = MAX(c.a, 0.0f);
float max = MAX(MAX(MAX(blue,green),red),1.0f);
ColorF32 scaled = {blue, green, red, alpha};
scaled /= max;
c.b = scaled.b;
c.g = scaled.g;
c.r = scaled.r;
c.a = scaled.a;
}
#define COLOR_H
#endif

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#ifndef ENGINE_H
#include "geometry.h"
#include <cstdint>
// WINDOW CONFIGURATION
#define WINDOW_WIDTH (1920)
#define WINDOW_HEIGHT (1080)
#define WINDOW_FPS (30)
// CAMERA CONFIGURATION
#define CAMERA_FOV (90.0f)
#define CAMERA_NEAR_CLIP (5.0f)
#define CAMERA_FAR_CLIP (600.0f)
// ENUMS
enum EngineInput
{
TRANSLATE_X_POS,
TRANSLATE_X_NEG,
TRANSLATE_Y_POS,
TRANSLATE_Y_NEG,
TRANSLATE_Z_POS,
TRANSLATE_Z_NEG,
ROTATE_X_POS,
ROTATE_X_NEG,
ROTATE_Y_POS,
ROTATE_Y_NEG,
ROTATE_Z_POS,
ROTATE_Z_NEG,
SCALE_UP,
SCALE_DOWN
};
// STRUCTURES
struct EngineBuffer
{
uint32_t *buffer;
int width;
int height;
};
struct EngineMemory
{
float zbuffer[WINDOW_HEIGHT][WINDOW_WIDTH];
VertexList localVerts;
VertexList transVerts;
FaceList localFaces;
FaceList transFaces;
UVList uvs;
MaterialList materials;
TextureList textures;
};
// FUNCTIONS
int EngineInit(char *objFilename, char *mtlFilename);
void EngineRender(EngineBuffer &buffer, uint32_t input);
void EngineShutdown(void);
#define ENGINE_H
#endif

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#ifndef GEOMETRY_H
#include "color.h"
#include "point.h"
#include <cstdint>
// CONSTANTS
#define FACE_LIMIT (30000)
#define MATERIAL_LIMIT (5)
#define TEXTURE_SIZE_LIMIT (1024)
#define VERTEX_LIMIT (20000)
// STRUCTURES
struct Texture
{
ColorU32 texels[TEXTURE_SIZE_LIMIT][TEXTURE_SIZE_LIMIT];
unsigned int width;
unsigned int height;
};
struct TextureList
{
Texture data[MATERIAL_LIMIT];
size_t size;
};
struct Material
{
ColorF32 ambient;
ColorF32 diffuse;
ColorF32 specular;
float glossiness;
float opacity;
};
struct MaterialList
{
Material data[MATERIAL_LIMIT];
size_t size;
};
struct UV
{
float u;
float v;
};
struct UVList
{
UV data[VERTEX_LIMIT];
size_t size;
};
struct Vertex
{
Point position;
Vector normal;
ColorF32 color;
};
struct VertexList
{
Vertex data[VERTEX_LIMIT];
size_t size;
};
struct Face
{
int vertIndex[3];
int uvIndex[3];
int materialIndex;
};
struct FaceList
{
Face data[FACE_LIMIT];
size_t size;
};
struct Mesh
{
Point position;
Point rotation;
float scale;
};
#define GEOMETRY_H
#endif

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#ifndef LIGHT_H
#include "camera.h"
#include "color.h"
#include "geometry.h"
#include "point.h"
// STRUCTURES
struct Light
{
Point position;
ColorF32 color;
float intensity;
float falloffConstant;
float falloffLinear;
};
// PUBLIC FUNCTIONS
ColorF32 ComputeLight(Point &position, Vector &normal, Material &material, Light &light, Camera &camera);
#define LIGHT_H
#endif

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#ifndef LOADER_H
#include "engine.h"
#include "geometry.h"
int ParseOBJ(char *filename, EngineMemory &memory);
int ParseMTL(char *filename, EngineMemory &memory);
#define LOADER_H
#endif

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#ifndef MATRIX_H
#include "point.h"
// STRUCTURE
struct Matrix
{
inline Matrix(void)
{
e11 = 1.0; e12 = 0.0; e13 = 0.0; e14 = 0.0;
e21 = 0.0; e22 = 1.0; e23 = 0.0; e24 = 0.0;
e31 = 0.0; e32 = 0.0; e33 = 1.0; e34 = 0.0;
e41 = 0.0; e42 = 0.0; e43 = 0.0; e44 = 1.0;
}
union
{
float e[4][4];
struct
{
float e11, e12, e13, e14;
float e21, e22, e23, e24;
float e31, e32, e33, e34;
float e41, e42, e43, e44;
};
};
};
// OPERATORS
// m1 * m2
inline Matrix operator*(Matrix const &m1, Matrix const &m2)
{
Matrix result;
for (int row = 0; row < 4; ++row)
{
for (int col = 0; col < 4; ++col)
{
float sum = 0.0;
for (int i = 0; i < 4; ++i)
{
sum += m1.e[row][i] * m2.e[i][col];
}
result.e[row][col] = sum;
}
}
return result;
}
// v * m
inline Point operator*(Point const &v, Matrix const &m)
{
Point result;
for (int col = 0; col < 4; ++col)
{
float sum = 0.0;
for (int row = 0; row < 4; ++row)
{
sum += v.e[row] * m.e[row][col];
}
result.e[col] = sum;
}
return result;
}
// v *=m
inline Point &operator*=(Point &v, Matrix const &m)
{
v = v * m;
return v;
}
// v * m
inline Vector operator*(Vector const &v, Matrix const &m)
{
Vector result;
for (int col = 0; col < 4; ++col)
{
float sum = 0.0;
for (int row = 0; row < 4; ++row)
{
sum += v.e[row] * m.e[row][col];
}
result.e[col] = sum;
}
return result;
}
#define MATRIX_H
#endif

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#ifndef PLATFORM_H
#include <SDL2/SDL.h>
// ENUMERATIONS
enum Platform_Status
{
PLATFORM_ERROR = -1,
PLATFORM_OK,
PLATFORM_QUIT
};
// STRUCTURES
struct Platform
{
SDL_Window *window;
SDL_Surface *surface;
uint32_t input;
uint32_t framerateMillis;
uint32_t frameStartMillis;
};
// FUNCTIONS
int Platform_Init(Platform &platform, int width, int height);
int Platform_CheckForEvents(Platform &platform);
void Platform_ClearWindow(Platform &platform);
void Platform_UpdateWindow(Platform &platform);
void Platform_GetFrameTime(Platform &platform);
void Platform_SyncToFramerate(Platform &platform);
void Platform_Shutdown(Platform &platform);
#define PLATFORM_H
#endif

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#ifndef POINT_H
#include "vec.h"
// STRUCTURE
struct Point
{
inline Point(void) : x(0), y(0), z(0), w(1) {}
inline Point(float x, float y, float z) : x(x), y(y), z(z), w(1) {}
union
{
float e[4];
struct
{
float x, y, z, w;
};
};
};
// OPERATORS
// p / f
inline Point operator/(Point const &p, float f)
{
Point result;
float inverse = 1.0f / f;
result.x = p.x * inverse;
result.y = p.y * inverse;
result.z = p.z * inverse;
return result;
}
// v /= f
inline Point &operator/=(Point &p, float f)
{
p = p / f;
return p;
}
// p1 - p2
inline Vector operator-(Point const &p1, Point const &p2)
{
Vector result;
result.x = p1.x - p2.x;
result.y = p1.y - p2.y;
result.z = p1.z - p2.z;
return result;
}
// -p
inline Point operator-(Point const &p)
{
Point result;
result.x = -p.x;
result.y = -p.y;
result.z = -p.z;
return result;
}
#define POINT_H
#endif

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#ifndef RENDER_H
#include "engine.h"
// PUBLIC FUNCTIONS
void Render(EngineBuffer &buffer, EngineMemory &memory);
#define RENDER_H
#endif

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#ifndef TRANSFORM_H
#include "camera.h"
#include "matrix.h"
Matrix Transform_Translate(Point &translation);
Matrix Transform_Rotate(Point &rotation);
Matrix Transform_Scale(float scale);
Matrix Transform_View(Camera &camera);
Matrix Transform_Perspective(Camera &camera);
Matrix Transform_Screen(Camera &camera);
#define TRANSFORM_H
#endif

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#ifndef UTIL_H
#include <cmath>
// CONSTANTS
const float EPSILON_E3 = 1E-3f;
// MACROS
#define SET_BIT(x, bit) (x |= (1UL << bit))
#define CLEAR_BIT(x, bit) (x &= ~(1UL << bit))
#define CHECK_BIT(x, bit) (x & (1UL << bit))
#define DEG_TO_RAD(deg) ((deg * (float)M_PI) / 180.0f)
#define SWAP(a, b, temp) {temp = a; a = b; b = temp;}
#define MIN(a, b) ((a < b) ? a : b)
#define MAX(a, b) ((a > b) ? a : b)
#define FLOAT_EQUAL(a, b) ((fabsf(a - b) < EPSILON_E3) ? 1 : 0)
#define UTIL_H
#endif

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#ifndef VEC_H
#include "util.h"
#include <cmath>
// STRUCTURE
struct Vector
{
inline Vector(void) : x(0), y(0), z(0), w(0) {}
inline Vector(float x, float y, float z) : x(x), y(y), z(z), w(0) {}
union
{
float e[4];
struct
{
float x, y, z, w;
};
};
};
// OPERATORS
// -v
inline Vector operator-(Vector const &v)
{
Vector result;
result.x = -v.x;
result.y = -v.y;
result.z = -v.z;
return result;
}
// v1 - v2
inline Vector operator-(Vector const &v1, Vector const &v2)
{
Vector result;
result.x = v1.x - v2.x;
result.y = v1.y - v2.y;
result.z = v1.z - v2.z;
return result;
}
// v1 + v2
inline Vector operator+(Vector const &v1, Vector const &v2)
{
Vector result;
result.x = v1.x + v2.x;
result.y = v1.y + v2.y;
result.z = v1.z + v2.z;
return result;
}
// v1 += v2
inline Vector &operator+=(Vector &v1, Vector const &v2)
{
v1 = v1 + v2;
return v1;
}
// f * v
inline Vector operator*(float f, Vector const &v)
{
Vector result;
result.x = v.x * f;
result.y = v.y * f;
result.z = v.z * f;
return result;
}
// v / f
inline Vector operator/(Vector const &v, float f)
{
Vector result;
float inverse = 1.0f / f;
result.x = v.x * inverse;
result.y = v.y * inverse;
result.z = v.z * inverse;
return result;
}
// v /= f
inline Vector &operator/=(Vector &v, float f)
{
v = v / f;
return v;
}
// PUBLIC FUNCTIONS
inline float VectorLength(Vector &v)
{
float result = sqrtf(v.x * v.x + v.y * v.y + v.z * v.z);
// zero length
if (result < EPSILON_E3)
{
result = 0.0f;
}
return result;
}
inline void VectorNormalize(Vector &v)
{
float length = VectorLength(v);
// zero length
if (length == 0.0f)
{
v.x = 0.0f;
v.y = 0.0f;
v.z = 0.0f;
}
else
{
float lengthInv = 1.0f / length;
v.x *= lengthInv;
v.y *= lengthInv;
v.z *= lengthInv;
}
}
inline Vector VectorCross(Vector &v1, Vector &v2)
{
Vector result;
result.x = (v1.y * v2.z) - (v1.z * v2.y);
result.y = (v1.z * v2.x) - (v1.x * v2.z);
result.z = (v1.x * v2.y) - (v1.y * v2.x);
return result;
}
inline float VectorDot(Vector &v1, Vector &v2)
{
float result;
result = (v1.x * v2.x) + (v1.y * v2.y) + (v1.z * v2.z);
return result;
}
#define VEC_H
#endif

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#include "camera.h"
#include "color.h"
#include "engine.h"
#include "geometry.h"
#include "light.h"
#include "loader.h"
#include "matrix.h"
#include "render.h"
#include "transform.h"
#include "util.h"
#include "vec.h"
#include <cstring>
#include <cstdio>
// GLOBALS
static Mesh mesh;
static Camera camera;
static Light light;
static Matrix tPersp;
static Matrix tScreen;
static EngineMemory memory;
// PRIVATE PROTOTYPES
static void ComputeNormals(void);
static void CheckInputs(uint32_t input);
static void ClearDepthBuffer(void);
static void TransformToClipSpace(void);
static void ClipAndCull(void);
static void TransformToScreenSpace(void);
static void LightMesh(void);
// PUBLIC FUNCTIONS
int EngineInit(char *objFilename, char *mtlFilename)
{
int result;
result = ParseOBJ(objFilename, memory);
if (result < 0)
{
return -1;
}
result = ParseMTL(mtlFilename, memory);
if (result < 0)
{
return -1;
}
printf("Verts: %lu\n", memory.localVerts.size);
printf("Faces: %lu\n", memory.localFaces.size);
printf("Materials: %lu\n", memory.materials.size);
memory.transVerts.size = memory.localVerts.size;
// Compute vertex and face normals for lighting calculation
ComputeNormals();
// Mesh configuration
mesh.position.z = 200;
mesh.position.y = -100;
mesh.scale = 1.0f;
// Light configuration
light.position = Point(-300.0f, 200.0f, 0.0f);
light.color = {1.0f, 1.0f, 1.0f, 1.0f};
light.intensity = 2.0f;
light.falloffConstant = 1.0f;
light.falloffLinear = 0.001f;
// Transformation matrices that do not change
tPersp = Transform_Perspective(camera);
tScreen = Transform_Screen(camera);
return 0;
}
void EngineRender(EngineBuffer &buffer, uint32_t input)
{
// Check for user input
CheckInputs(input);
// Clear the z-buffer
ClearDepthBuffer();
// Transform vertices to clip space
TransformToClipSpace();
// Clip near/far Z and cull backfaces
ClipAndCull();
// Light vertices and/or faces
LightMesh();
// Transform vertices to screen space
TransformToScreenSpace();
// Render
Render(buffer, memory);
}
void EngineShutdown(void)
{
}
// PRIVATE FUNCTIONS
static void CheckInputs(uint32_t input)
{
if (CHECK_BIT(input, TRANSLATE_X_POS))
{
light.position.x += 10;
}
else if (CHECK_BIT(input, TRANSLATE_X_NEG))
{
light.position.x -= 10;
}
if (CHECK_BIT(input, TRANSLATE_Z_POS))
{
light.position.z += 10;
}
else if (CHECK_BIT(input, TRANSLATE_Z_NEG))
{
light.position.z -= 10;
}
if (CHECK_BIT(input, TRANSLATE_Y_POS))
{
light.position.y += 10;
}
else if (CHECK_BIT(input, TRANSLATE_Y_NEG))
{
light.position.y -= 10;
}
if (CHECK_BIT(input, ROTATE_X_POS))
{
mesh.rotation.x += 0.10f;
}
else if (CHECK_BIT(input, ROTATE_X_NEG))
{
mesh.rotation.x -= 0.10f;
}
if (CHECK_BIT(input, ROTATE_Y_POS))
{
mesh.rotation.y += 0.10f;
}
else if (CHECK_BIT(input, ROTATE_Y_NEG))
{
mesh.rotation.y -= 0.10f;
}
if (CHECK_BIT(input, ROTATE_Z_POS))
{
mesh.rotation.z += 0.10f;
}
else if (CHECK_BIT(input, ROTATE_Z_NEG))
{
mesh.rotation.z -= 0.10f;
}
if (CHECK_BIT(input, SCALE_UP))
{
light.color.b = 0.0f;
light.color.g = 0.0f;
light.color.r = 1.0f;
}
else if (CHECK_BIT(input, SCALE_DOWN))
{
light.color.b = 1.0f;
light.color.g = 1.0f;
light.color.r = 1.0f;
}
}
static void ComputeNormals(void)
{
VertexList &verts = memory.localVerts;
FaceList &faces = memory.localFaces;
int vertexNormalCount[VERTEX_LIMIT] = {};
for (size_t f = 0; f < faces.size; ++f)
{
Face &face = faces.data[f];
Vertex &vert0 = verts.data[face.vertIndex[0]];
Vertex &vert1 = verts.data[face.vertIndex[1]];
Vertex &vert2 = verts.data[face.vertIndex[2]];
Vector v01 = vert1.position - vert0.position;
Vector v02 = vert2.position - vert0.position;
Vector normal = VectorCross(v01, v02);
// Add each vertex's normal to the sum for future averaging
vert0.normal += normal;
vert1.normal += normal;
vert2.normal += normal;
++vertexNormalCount[face.vertIndex[0]];
++vertexNormalCount[face.vertIndex[1]];
++vertexNormalCount[face.vertIndex[2]];
}
for (size_t v = 0; v < verts.size; ++v)
{
if (vertexNormalCount[v] > 0)
{
// Compute the average normal for this vertex
verts.data[v].normal /= vertexNormalCount[v];
VectorNormalize(verts.data[v].normal);
}
}
}
static void ClearDepthBuffer(void)
{
memset(memory.zbuffer, 0, sizeof(memory.zbuffer));
}
static void TransformToClipSpace(void)
{
VertexList &localVerts = memory.localVerts;
VertexList &transVerts = memory.transVerts;
Matrix tTranslate = Transform_Translate(mesh.position);
Matrix tRotate = Transform_Rotate(mesh.rotation);
Matrix tScale = Transform_Scale(mesh.scale);
Matrix tView = Transform_View(camera);
for (size_t v = 0; v < localVerts.size; ++v)
{
transVerts.data[v].position =
localVerts.data[v].position * tScale * tRotate * tTranslate * tView * tPersp;
transVerts.data[v].normal =
localVerts.data[v].normal * tScale * tRotate * tTranslate;
}
}
void ClipAndCull(void)
{
FaceList &localFaces = memory.localFaces;
FaceList &transFaces = memory.transFaces;
VertexList &verts = memory.transVerts;
int faceIndex = 0;
for (size_t f = 0; f < localFaces.size; ++f)
{
Face &face = localFaces.data[f];
Point &p0 = verts.data[face.vertIndex[0]].position;
Point &p1 = verts.data[face.vertIndex[1]].position;
Point &p2 = verts.data[face.vertIndex[2]].position;
// Ignore this face if its Z is outside the Z clip planes
if ( (p0.z < -p0.w)
|| (p0.z > p0.w)
|| (p1.z < -p1.w)
|| (p1.z > p1.w)
|| (p2.z < -p2.w)
|| (p2.z > p2.w))
{
continue;
}
// Calculate the face's normal (inverted for Blender-compatibility)
Vector v01 = p1 - p0;
Vector v02 = p2 - p0;
Vector normal = -VectorCross(v01, v02);
// Eye vector to viewport
Vector view = camera.position - p0;
float dot = VectorDot(normal, view);
// Not a backface; add it to the list
if (dot < EPSILON_E3)
{
transFaces.data[faceIndex] = face;
++faceIndex;
transFaces.size = (size_t)faceIndex;
}
}
}
static void TransformToScreenSpace(void)
{
VertexList &verts = memory.transVerts;
for (size_t v = 0; v < verts.size; ++v)
{
verts.data[v].position *= tScreen;
verts.data[v].position.x /= verts.data[v].position.w;
verts.data[v].position.y /= verts.data[v].position.w;
verts.data[v].position.z /= verts.data[v].position.w;
}
}
static void LightMesh(void)
{
VertexList &verts = memory.transVerts;
FaceList &faces = memory.transFaces;
MaterialList &materials = memory.materials;
for (size_t f = 0; f < faces.size; ++f)
{
Face &face = faces.data[f];
Material &material = materials.data[face.materialIndex];
// Gouraud shading
for (int i = 0; i < 3; ++i)
{
Vertex &vert = verts.data[face.vertIndex[i]];
vert.color = ComputeLight(vert.position, vert.normal, material, light, camera);
}
}
}

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#include "camera.h"
#include "color.h"
#include "light.h"
// PUBLIC FUNCTIONS
ColorF32 ComputeLight(
Point &position, Vector &normal, Material &material, Light &light, Camera &camera)
{
// Point light intensity is a function of the falloff factors and the distance
Vector direction = light.position - position;
VectorNormalize(direction);
float distance = VectorLength(direction);
ColorF32 intensity =
(light.intensity * light.color)
/ (light.falloffConstant + (light.falloffLinear * distance));
// Diffuse Light = Kr * I * (alpha + (1 - alpha) * n.d)
float dotNormalDirection = MAX(VectorDot(normal, direction), 0.0f);
float alpha = 0.2f;
ColorF32 diffuseLight =
material.diffuse
* intensity
* (alpha + (1.0f - alpha) * dotNormalDirection);
// Specular Light = Ks * I * (r.v)^sp
Vector view = camera.position - position;
VectorNormalize(view);
Vector reflection = (2.0f * dotNormalDirection * normal) - direction;
float dotReflectionView = MAX(VectorDot(reflection, view), 0.0f);
ColorF32 specularLight =
material.specular
* intensity
* powf(dotReflectionView, material.glossiness);
// Total light is sum of all lights
ColorF32 result = diffuseLight + specularLight;
return result;
}

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#include "engine.h"
#include "loader.h"
#include <cctype>
#include <cstdio>
#include <cstdint>
#include <cstdlib>
#include <cstring>
// STATIC PROTOTYPES
static int LoadTexture(char *filename, Texture &texture, float opacity);
#pragma pack(push, 1)
struct BMP_Header
{
uint16_t fileType;
uint32_t fileSize;
uint16_t reserved0;
uint16_t reserved1;
uint32_t bitmapOffset;
uint32_t size;
int32_t width;
int32_t height;
uint16_t planes;
uint16_t bitsPerPixel;
uint32_t compression;
uint32_t sizeOfBitmap;
int32_t horizRes;
int32_t vertRes;
uint32_t colorsUsed;
uint32_t colorsImportant;
};
#pragma pack(pop)
// PUBLIC FUNCTIONS
int ParseOBJ(char *filename, EngineMemory &memory)
{
FILE *fp = fopen(filename, "r");
if (fp == NULL)
{
fprintf(stderr, "Error loading file: %s\n", filename);
return -1;
}
char line[256];
int vertIndex = 0;
int uvIndex = 0;
int faceIndex = 0;
int materialIndex = -1;
VertexList &verts = memory.localVerts;
FaceList &faces = memory.localFaces;
UVList &uvs = memory.uvs;
while (fgets(line, sizeof(line), fp))
{
char *separator = strchr(line, ' ');
if (separator != NULL)
{
*separator = '\0';
char *type = line;
char *data = separator + 1;
if (strcmp(type, "v") == 0)
{
sscanf( data, "%f %f %f",
&verts.data[vertIndex].position.x,
&verts.data[vertIndex].position.y,
&verts.data[vertIndex].position.z);
verts.data[vertIndex].position.w = 1.0f;
++vertIndex;
}
else if (strcmp(type, "vt") == 0)
{
sscanf( data, "%f %f",
&uvs.data[uvIndex].u,
&uvs.data[uvIndex].v);
++uvIndex;
}
else if (strcmp(type, "usemtl") == 0)
{
++materialIndex;
}
else if (strcmp(type, "f") == 0)
{
sscanf( data, "%d/%d %d/%d %d/%d",
&faces.data[faceIndex].vertIndex[0],
&faces.data[faceIndex].uvIndex[0],
&faces.data[faceIndex].vertIndex[1],
&faces.data[faceIndex].uvIndex[1],
&faces.data[faceIndex].vertIndex[2],
&faces.data[faceIndex].uvIndex[2]);
// Convert to 0-indexed
faces.data[faceIndex].vertIndex[0] -= 1;
faces.data[faceIndex].vertIndex[1] -= 1;
faces.data[faceIndex].vertIndex[2] -= 1;
faces.data[faceIndex].uvIndex[0] -= 1;
faces.data[faceIndex].uvIndex[1] -= 1;
faces.data[faceIndex].uvIndex[2] -= 1;
faces.data[faceIndex].materialIndex = materialIndex;
++faceIndex;
}
}
}
verts.size = (size_t)vertIndex;
uvs.size = (size_t)uvIndex;
faces.size = (size_t)faceIndex;
return 0;
}
int ParseMTL(char *filename, EngineMemory &memory)
{
FILE *fp = fopen(filename, "r");
if (fp == NULL)
{
fprintf(stderr, "Error loading file: %s\n", filename);
return -1;
}
char line[256];
int materialIndex = -1;
MaterialList &materials = memory.materials;
TextureList &textures = memory.textures;
while (fgets(line, sizeof(line), fp))
{
char *separator = strchr(line, ' ');
if (separator != NULL)
{
*separator = '\0';
char *type = line;
char *data = separator + 1;
if (strcmp(type, "newmtl") == 0)
{
++materialIndex;
}
else if (strcmp(type, "Ns") == 0)
{
sscanf( data, "%f",
&materials.data[materialIndex].glossiness);
}
else if (strcmp(type, "Ka") == 0)
{
sscanf( data, "%f %f %f",
&materials.data[materialIndex].ambient.r,
&materials.data[materialIndex].ambient.g,
&materials.data[materialIndex].ambient.b);
}
else if (strcmp(type, "Kd") == 0)
{
sscanf( data, "%f %f %f",
&materials.data[materialIndex].diffuse.r,
&materials.data[materialIndex].diffuse.g,
&materials.data[materialIndex].diffuse.b);
}
else if (strcmp(type, "Ks") == 0)
{
sscanf( data, "%f %f %f",
&materials.data[materialIndex].specular.r,
&materials.data[materialIndex].specular.g,
&materials.data[materialIndex].specular.b);
}
else if (strcmp(type, "d") == 0)
{
sscanf( data, "%f",
&materials.data[materialIndex].opacity);
}
else if (strcmp(type, "map_Kd") == 0)
{
char *textureFilename = data;
textureFilename[strcspn(textureFilename, "\r\n")] = 0;
LoadTexture(
textureFilename, textures.data[materialIndex],
materials.data[materialIndex].opacity);
}
}
}
materials.size = (size_t)(materialIndex + 1);
return 0;
}
static int LoadTexture(char *filename, Texture &texture, float opacity)
{
FILE *fp = fopen(filename, "r");
if (fp == NULL)
{
fprintf(stderr, "Could not open file: %s\n", filename);
return -1;
}
BMP_Header header = {};
fread((void*)&header, sizeof(BMP_Header), 1, fp);
fseek(fp, header.bitmapOffset, SEEK_SET);
// Padding is added to image to align to 4-byte boundaries
size_t paddingSize = header.width % 4;
for (int y = 0; y < header.height; ++y)
{
for (int x = 0; x < header.width; ++x)
{
fread(&texture.texels[y][x].b, 1, 1, fp);
fread(&texture.texels[y][x].g, 1, 1, fp);
fread(&texture.texels[y][x].r, 1, 1, fp);
texture.texels[y][x].a = (uint8_t)(255 * opacity);
}
// Discard padding byte
if (paddingSize != 0)
{
uint32_t padding;
fread(&padding, paddingSize, 1, fp);
}
}
texture.width = (unsigned int)header.width;
texture.height = (unsigned int)header.height;
fclose(fp);
return 0;
}

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#include "engine.h"
#include "platform.h"
#include <cstdint>
#include <cstdio>
#include <cstdlib>
// MAIN
int main(int argc, char *argv[])
{
if (argc != 3)
{
fprintf(stderr, "Usage: %s <OBJ> <MTL>\n", argv[0]);
return EXIT_FAILURE;
}
char *objFilename = argv[1];
char *mtlFilename = argv[2];
Platform platform = {};
int result = Platform_Init(platform, WINDOW_WIDTH, WINDOW_HEIGHT);
platform.framerateMillis = (1000 / WINDOW_FPS);
if (result == PLATFORM_OK)
{
EngineBuffer buffer = {};
buffer.buffer = (uint32_t*)platform.surface->pixels;
buffer.width = platform.surface->w;
buffer.height = platform.surface->h;
result = EngineInit(objFilename, mtlFilename);
if (result < 0)
{
return EXIT_FAILURE;
}
while (true)
{
Platform_GetFrameTime(platform);
result = Platform_CheckForEvents(platform);
if (result == PLATFORM_QUIT)
{
break;
}
Platform_ClearWindow(platform);
EngineRender(buffer, platform.input);
Platform_UpdateWindow(platform);
Platform_SyncToFramerate(platform);
}
EngineShutdown();
Platform_Shutdown(platform);
}
else
{
return EXIT_FAILURE;
}
return EXIT_SUCCESS;
}

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#include "engine.h"
#include "platform.h"
#include "util.h"
#include <cstdint>
#include <SDL2/SDL.h>
// PRIVATE PROTOTYPES
static void HandleEvent(Platform &platform, SDL_Event &event);
// PUBLIC FUNCTIONS
int Platform_Init(Platform &platform, int width, int height)
{
int result = SDL_Init(SDL_INIT_VIDEO);
if (result < 0)
{
fprintf(stderr, "Error initializing SDL: %s\n", SDL_GetError());
return PLATFORM_ERROR;
}
SDL_Window *window = SDL_CreateWindow(
"Soft 3D Engine",
SDL_WINDOWPOS_UNDEFINED, SDL_WINDOWPOS_UNDEFINED,
width, height,
SDL_WINDOW_SHOWN);
if (window == NULL)
{
fprintf(stderr, "Error creating SDL window: %s\n", SDL_GetError());
return PLATFORM_ERROR;
}
SDL_Surface *surface = SDL_GetWindowSurface(window);
if (surface == NULL)
{
fprintf(stderr, "Error getting SDL window surface: %s\n", SDL_GetError());
return PLATFORM_ERROR;
}
result = SDL_ShowCursor(SDL_DISABLE);
if (result < 0)
{
fprintf(stderr, "Error disabling cursor in SDL window: %s\n", SDL_GetError());
return PLATFORM_ERROR;
}
platform.window = window;
platform.surface = surface;
return PLATFORM_OK;
}
int Platform_CheckForEvents(Platform &platform)
{
SDL_Event event;
while (SDL_PollEvent(&event) != 0)
{
if (event.type == SDL_QUIT)
{
return PLATFORM_QUIT;
}
else
{
HandleEvent(platform, event);
}
}
return PLATFORM_OK;
}
void Platform_ClearWindow(Platform &platform)
{
SDL_LockSurface(platform.surface);
SDL_FillRect(platform.surface, NULL, 0);
}
void Platform_UpdateWindow(Platform &platform)
{
SDL_UnlockSurface(platform.surface);
SDL_UpdateWindowSurface(platform.window);
}
void Platform_GetFrameTime(Platform &platform)
{
platform.frameStartMillis = SDL_GetTicks();
}
void Platform_SyncToFramerate(Platform &platform)
{
uint32_t stopTimeMillis = SDL_GetTicks();
uint32_t framerateMillis = stopTimeMillis - platform.frameStartMillis;
// Delay if time to spare
if (framerateMillis < platform.framerateMillis)
{
uint32_t delayMillis = platform.framerateMillis - framerateMillis;
SDL_Delay(delayMillis);
}
}
void Platform_Shutdown(Platform &platform)
{
SDL_DestroyWindow(platform.window);
SDL_Quit();
}
// PRIVATE FUNCTIONS
static void HandleEvent(
Platform &platform, SDL_Event &event)
{
switch(event.type)
{
case SDL_KEYDOWN:
{
switch (event.key.keysym.sym)
{
case SDLK_w:
{
SET_BIT(platform.input, TRANSLATE_Z_POS);
} break;
case SDLK_s:
{
SET_BIT(platform.input, TRANSLATE_Z_NEG);
} break;
case SDLK_a:
{
SET_BIT(platform.input, TRANSLATE_X_NEG);
} break;
case SDLK_d:
{
SET_BIT(platform.input, TRANSLATE_X_POS);
} break;
case SDLK_q:
{
SET_BIT(platform.input, TRANSLATE_Y_POS);
} break;
case SDLK_e:
{
SET_BIT(platform.input, TRANSLATE_Y_NEG);
} break;
case SDLK_i:
{
SET_BIT(platform.input, ROTATE_X_POS);
} break;
case SDLK_k:
{
SET_BIT(platform.input, ROTATE_X_NEG);
} break;
case SDLK_j:
{
SET_BIT(platform.input, ROTATE_Y_POS);
} break;
case SDLK_l:
{
SET_BIT(platform.input, ROTATE_Y_NEG);
} break;
case SDLK_u:
{
SET_BIT(platform.input, ROTATE_Z_POS);
} break;
case SDLK_o:
{
SET_BIT(platform.input, ROTATE_Z_NEG);
} break;
case SDLK_UP:
{
SET_BIT(platform.input, SCALE_UP);
} break;
case SDLK_DOWN:
{
SET_BIT(platform.input, SCALE_DOWN);
} break;
}
} break;
case SDL_KEYUP:
{
switch (event.key.keysym.sym)
{
case SDLK_w:
{
CLEAR_BIT(platform.input, TRANSLATE_Z_POS);
} break;
case SDLK_s:
{
CLEAR_BIT(platform.input, TRANSLATE_Z_NEG);
} break;
case SDLK_a:
{
CLEAR_BIT(platform.input, TRANSLATE_X_NEG);
} break;
case SDLK_d:
{
CLEAR_BIT(platform.input, TRANSLATE_X_POS);
} break;
case SDLK_q:
{
CLEAR_BIT(platform.input, TRANSLATE_Y_POS);
} break;
case SDLK_e:
{
CLEAR_BIT(platform.input, TRANSLATE_Y_NEG);
} break;
case SDLK_i:
{
CLEAR_BIT(platform.input, ROTATE_X_POS);
} break;
case SDLK_k:
{
CLEAR_BIT(platform.input, ROTATE_X_NEG);
} break;
case SDLK_j:
{
CLEAR_BIT(platform.input, ROTATE_Y_POS);
} break;
case SDLK_l:
{
CLEAR_BIT(platform.input, ROTATE_Y_NEG);
} break;
case SDLK_u:
{
CLEAR_BIT(platform.input, ROTATE_Z_POS);
} break;
case SDLK_o:
{
CLEAR_BIT(platform.input, ROTATE_Z_NEG);
} break;
case SDLK_UP:
{
CLEAR_BIT(platform.input, SCALE_UP);
} break;
case SDLK_DOWN:
{
CLEAR_BIT(platform.input, SCALE_DOWN);
} break;
}
} break;
}
}

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#include "color.h"
#include "engine.h"
#include "geometry.h"
#include "render.h"
#include "util.h"
// MACROS
#define DrawPixel(buffer, width, color, x, y)\
{\
buffer[width * y + x] = color;\
}
// STRUCTURES
struct BoundingBox
{
BoundingBox(Point &v0, Point &v1, Point &v2)
{
yMin = MIN(v0.y, MIN(v1.y, v2.y));
yMax = MAX(v0.y, MAX(v1.y, v2.y));
xMin = MIN(v0.x, MIN(v1.x, v2.x));
xMax = MAX(v0.x, MAX(v1.x, v2.x));
}
float yMin, yMax;
float xMin, xMax;
};
// PUBLIC FUNCTIONS
void Render(EngineBuffer &buffer, EngineMemory &memory)
{
FaceList &faces = memory.transFaces;
VertexList &verts = memory.transVerts;
TextureList &textures = memory.textures;
UVList &uvs = memory.uvs;
for(size_t f = 0; f < faces.size; ++f)
{
Face &face = faces.data[f];
Point &p0 = verts.data[face.vertIndex[0]].position;
Point &p1 = verts.data[face.vertIndex[1]].position;
Point &p2 = verts.data[face.vertIndex[2]].position;
// Bounding box for barycentric calculations (top-left fill convention)
BoundingBox box(p0, p1, p2);
int yMin = (int)MAX(ceilf(box.yMin), 0);
int yMax = (int)MIN(ceilf(box.yMax) - 1, buffer.height - 1);
int xMin = (int)MAX(ceilf(box.xMin), 0);
int xMax = (int)MIN(ceilf(box.xMax) - 1, buffer.width - 1);
// Constants for this triangle used for barycentric calculations
Vector v01 = p1 - p0;
Vector v02 = p2 - p0;
float dot0101 = VectorDot(v01, v01);
float dot0102 = VectorDot(v01, v02);
float dot0202 = VectorDot(v02, v02);
// Iterate over the bounding box and determine if each point is in the triangle
for (int y = yMin; y <= yMax; ++y)
{
for (int x = xMin; x <= xMax; ++x)
{
// Calculate the barycentric coordinate of this point
Point p(x, y, 1.0f);
Vector v0P = p - p0;
float dot0P01 = VectorDot(v0P, v01);
float dot0P02 = VectorDot(v0P, v02);
float denomInv = 1.0f / ((dot0101 * dot0202) - (dot0102 * dot0102));
float barycenter[3];
barycenter[1] = (dot0202 * dot0P01 - dot0102 * dot0P02) * denomInv;
barycenter[2] = (dot0101 * dot0P02 - dot0102 * dot0P01) * denomInv;
barycenter[0] = 1.0f - barycenter[1] - barycenter[2];
// Point is inside the triangle
if ( (barycenter[0] >= 0.0f)
&& (barycenter[1] >= 0.0f)
&& (barycenter[2] >= 0.0f))
{
// Interpolate 1/z for the z-buffer
float zInv =
1.0f /
((barycenter[0] * p0.w)
+ (barycenter[1] * p1.w)
+ (barycenter[2] * p2.w));
// Compute pixel color if it's closer than what's in the z-buffer
if (zInv > memory.zbuffer[y][x])
{
// Update the depth buffer
memory.zbuffer[y][x] = zInv;
// Interpolate U and V of the texture for this point
Texture &texture = textures.data[faces.data[f].materialIndex];
UV &uv0 = uvs.data[face.uvIndex[0]];
UV &uv1 = uvs.data[face.uvIndex[1]];
UV &uv2 = uvs.data[face.uvIndex[2]];
float a = barycenter[0] * p1.w * p2.w;
float b = barycenter[1] * p0.w * p2.w;
float c = barycenter[2] * p0.w * p1.w;
float abc = 1.0f / (a + b + c);
float uInterp =
((a * uv0.u) + (b * uv1.u) + (c * uv2.u))
* abc
* texture.width;
float vInterp =
((a * uv0.v) + (b * uv1.v) + (c * uv2.v))
* abc
* texture.height;
// Bilinear filtering
unsigned int u = (unsigned int)uInterp;
unsigned int v = (unsigned int)vInterp;
float du = uInterp - u;
float dv = vInterp - v;
float duDiff = 1 - du;
float dvDiff = 1 - dv;
ColorU32 color =
{
(uint8_t)
(duDiff * dvDiff * texture.texels[v][u].b
+ du * dvDiff * texture.texels[v][u+1].b
+ du * dv * texture.texels[v+1][u+1].b
+ duDiff * dv * texture.texels[v+1][u].b),
(uint8_t)
(duDiff * dvDiff * texture.texels[v][u].g
+ du * dvDiff * texture.texels[v][u+1].g
+ du * dv * texture.texels[v+1][u+1].g
+ duDiff * dv * texture.texels[v+1][u].g),
(uint8_t)
(duDiff * dvDiff * texture.texels[v][u].r
+ du * dvDiff * texture.texels[v][u+1].r
+ du * dv * texture.texels[v+1][u+1].r
+ duDiff * dv * texture.texels[v+1][u].r),
(uint8_t)
(duDiff * dvDiff * texture.texels[v][u].a
+ du * dvDiff * texture.texels[v][u+1].a
+ du * dv * texture.texels[v+1][u+1].a
+ duDiff * dv * texture.texels[v+1][u].a)
};
// Perform Gouraud shading on the texture
ColorF32 &c0 = verts.data[face.vertIndex[0]].color;
ColorF32 &c1 = verts.data[face.vertIndex[1]].color;
ColorF32 &c2 = verts.data[face.vertIndex[2]].color;
ColorF32 shading =
(barycenter[0] * c0)
+ (barycenter[1] * c1)
+ (barycenter[2] * c2);
// Ensure no color channel exceeds max
ScaleColor(shading);
// Light the texture
color.b *= shading.b;
color.g *= shading.g;
color.r *= shading.r;
// Alpha blend the pixel
ColorU32 *pixel = (ColorU32*)&buffer.buffer[y*buffer.width+x];
float alpha = color.a / 255.0f;
float alphaDiff = 1.0f - alpha;
ColorU32 blended =
{
(uint8_t)((alpha * color.b) + (alphaDiff * pixel->b)),
(uint8_t)((alpha * color.g) + (alphaDiff * pixel->g)),
(uint8_t)((alpha * color.r) + (alphaDiff * pixel->r)),
(uint8_t)((alpha * color.a) + (alphaDiff * pixel->a))
};
// Draw
DrawPixel(buffer.buffer, buffer.width, blended.u32, x, y);
}
}
}
}
}
}

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#include "matrix.h"
#include "transform.h"
#include <cmath>
// PUBLIC FUNCTIONS
Matrix Transform_Translate(Point &translation)
{
Matrix result;
result.e41 = translation.x;
result.e42 = translation.y;
result.e43 = translation.z;
return result;
}
Matrix Transform_Rotate(Point &rotation)
{
// YXZ Euler rotation
float cosThetaY = cosf(rotation.y);
float sinThetaY = sinf(rotation.y);
Matrix tRotateY;
tRotateY.e11 = cosThetaY;
tRotateY.e13 = -sinThetaY;
tRotateY.e31 = sinThetaY;
tRotateY.e33 = cosThetaY;
float cosThetaX = cosf(rotation.x);
float sinThetaX = sinf(rotation.x);
Matrix tRotateX;
tRotateX.e22 = cosThetaX;
tRotateX.e23 = sinThetaX;
tRotateX.e32 = -sinThetaX;
tRotateX.e33 = cosThetaX;
float cosThetaZ = cosf(rotation.z);
float sinThetaZ = sinf(rotation.z);
Matrix tRotateZ;
tRotateZ.e11 = cosThetaZ;
tRotateZ.e12 = sinThetaZ;
tRotateZ.e21 = -sinThetaZ;
tRotateZ.e22 = cosThetaZ;
Matrix result = tRotateY * tRotateX * tRotateZ;
return result;
}
Matrix Transform_Scale(float scale)
{
Matrix result;
result.e11 = scale;
result.e22 = scale;
result.e33 = scale;
return result;
}
Matrix Transform_View(Camera &camera)
{
Point invPosition = -camera.position;
Matrix tInvTranslate = Transform_Translate(invPosition);
Point invRotation = -camera.rotation;
Matrix tInvRotate = Transform_Rotate(invRotation);
Matrix result = tInvTranslate * tInvRotate;
return result;
}
Matrix Transform_Perspective(Camera &camera)
{
Matrix result;
result.e11 = camera.xZoom;
result.e22 = camera.yZoom;
result.e33 = camera.zClipBias0;
result.e34 = 1;
result.e43 = camera.zClipBias1;
return result;
}
Matrix Transform_Screen(Camera &camera)
{
Matrix result;
result.e11 = camera.xScale;
result.e41 = camera.xScale;
result.e22 = -camera.yScale;
result.e42 = camera.yScale;
return result;
}