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2018-soft-3d-renderer
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Add inverse z-buffering

This commit is contained in:
Austin Morlan 2018-09-06 18:32:15 -07:00
parent 63e8bd1b93
commit 8ede3f1952
Signed by: austin
GPG Key ID: FD6B27654AF5E348
8 changed files with 126 additions and 53 deletions
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3
Makefile
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@ -31,7 +31,8 @@ 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-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

3
include/engine.h
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@ -26,7 +26,8 @@ enum Engine_Input
// STRUCTURES
struct Engine_Buffer
{
uint32_t *pixels;
uint32_t *buffer;
float *zbuffer;
int width;
int height;
};

9
include/geometry.h
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@ -77,10 +77,11 @@ struct Mesh
// PUBLIC FUNCTIONS
void FillTriangle(
uint32_t *buffer, int width, uint32_t color,
float x0, float y0,
float x1, float y1,
float x2, float y2);
uint32_t *buffer, int width,
float *zbuffer, uint32_t color,
float x0, float y0, float z0,
float x1, float y1, float z1,
float x2, float y2, float z2);
#define GEOMETRY_H

7
include/matrix.h
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@ -74,6 +74,13 @@ inline Point operator*(Point v, Matrix m)
return result;
}
inline Point &operator*=(Point &v, Matrix m)
{
v = v * m;
return v;
}
#define MATRIX_H
#endif

8
include/point.h
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@ -36,6 +36,14 @@ inline Point operator/(Point v, float f)
return result;
}
// v /= f
inline Point &operator/=(Point &v, float f)
{
v = v / f;
return v;
}
// v1 - v2
inline Vector operator-(Point v1, Point v2)
{

28
src/engine.cpp
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@ -8,7 +8,7 @@
#include "transform.h"
#include "util.h"
#include "vec.h"
#include <cstdio>
#include <cstring>
// GLOBALS
@ -50,6 +50,8 @@ void Engine_Render(Engine_Buffer &buffer, uint32_t input)
{
CheckInputs(input);
unsigned long bufferSize = (unsigned long)(buffer.width * buffer.height);
memset(buffer.zbuffer, 0, bufferSize * sizeof(float));
// Local space to world space
Matrix tTranslate = Transform_Translate(
@ -62,8 +64,7 @@ void Engine_Render(Engine_Buffer &buffer, uint32_t input)
for (size_t v = 0; v < mesh.verts.size(); ++v)
{
mesh.vertsTransformed[v] =
mesh.verts[v] * tScale * tRotate * tTranslate;
mesh.vertsTransformed[v] = mesh.verts[v] * tScale * tRotate * tTranslate;
}
@ -99,25 +100,17 @@ void Engine_Render(Engine_Buffer &buffer, uint32_t input)
// World space to camera (view) space
Matrix tView = Transform_View(camera.position, camera.rotation);
// Camera space to perspective
Matrix tPersp = Transform_Perspective(
camera.xZoom, camera.yZoom, camera.nearClip, camera.farClip);
for (size_t v = 0; v < mesh.verts.size(); ++v)
{
mesh.vertsTransformed[v] = mesh.vertsTransformed[v] * tView * tPersp;
mesh.vertsTransformed[v] =
mesh.vertsTransformed[v] / mesh.vertsTransformed[v].w;
}
// Perspective to screen
Matrix tScreen = Transform_Screen(camera.xScale, camera.yScale);
for (size_t v = 0; v < mesh.verts.size(); ++v)
{
mesh.vertsTransformed[v] = mesh.vertsTransformed[v] * tScreen;
mesh.vertsTransformed[v] *= tView * tPersp * tScreen;
mesh.vertsTransformed[v] /= mesh.vertsTransformed[v].w;
}
@ -129,10 +122,11 @@ void Engine_Render(Engine_Buffer &buffer, uint32_t input)
unsigned int v2 = mesh.culledFaces[f].vertIndex[2];
FillTriangle(
buffer.pixels, buffer.width, mesh.faces[f].color.u32,
mesh.vertsTransformed[v0].x, mesh.vertsTransformed[v0].y,
mesh.vertsTransformed[v1].x, mesh.vertsTransformed[v1].y,
mesh.vertsTransformed[v2].x, mesh.vertsTransformed[v2].y);
buffer.buffer, buffer.width,
buffer.zbuffer, mesh.faces[f].color.u32,
mesh.vertsTransformed[v0].x, mesh.vertsTransformed[v0].y, mesh.vertsTransformed[v0].z,
mesh.vertsTransformed[v1].x, mesh.vertsTransformed[v1].y, mesh.vertsTransformed[v1].z,
mesh.vertsTransformed[v2].x, mesh.vertsTransformed[v2].y, mesh.vertsTransformed[v2].z);
}
}

114
src/geometry.cpp
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@ -12,24 +12,27 @@
// PRIVATE PROTOTYPES
static void FillTriangleFlatBottom(
uint32_t *buffer, int width, uint32_t color,
float x0, float y0,
float x1, float y1,
float x2, float y2);
uint32_t *buffer, int width,
float *zbuffer, uint32_t color,
float x0, float y0, float z0,
float x1, float y1, float z1,
float x2, float y2, float z2);
static void FillTriangleFlatTop(
uint32_t *buffer, int width, uint32_t color,
float x0, float y0,
float x1, float y1,
float x2, float y2);
uint32_t *buffer, int width,
float *zbuffer, uint32_t color,
float x0, float y0, float z0,
float x1, float y1, float z1,
float x2, float y2, float z2);
// PUBLIC FUNCTIONS
void FillTriangle(
uint32_t *buffer, int width, uint32_t color,
float x0, float y0,
float x1, float y1,
float x2, float y2)
uint32_t *buffer, int width,
float *zbuffer, uint32_t color,
float x0, float y0, float z0,
float x1, float y1, float z1,
float x2, float y2, float z2)
{
// Horizontal or vertical
if ((FLOAT_EQUAL(x0,x1) && FLOAT_EQUAL(x1, x2))
@ -44,31 +47,34 @@ void FillTriangle(
{
SWAP(x0, x1, temp);
SWAP(y0, y1, temp);
SWAP(z0, z1, temp);
}
if (y0 > y2)
{
SWAP(x0, x2, temp);
SWAP(y0, y2, temp);
SWAP(z0, z2, temp);
}
if (y1 > y2)
{
SWAP(x1, x2, temp);
SWAP(y1, y2, temp);
SWAP(z1, z2, temp);
}
// Flat top triangle
if (FLOAT_EQUAL(y0, y1))
{
FillTriangleFlatTop(buffer, width, color, x0, y0, x1, y1, x2, y2);
FillTriangleFlatTop(buffer, width, zbuffer, color, x0, y0, z0, x1, y1, z1, x2, y2, z2);
}
// Flat bottom triangle
else if (FLOAT_EQUAL(y1, y2))
{
FillTriangleFlatBottom(buffer, width, color, x0, y0, x1, y1, x2, y2);
FillTriangleFlatBottom(buffer, width, zbuffer, color, x0, y0, z0, x1, y1, z1, x2, y2, z2);
}
// Other - decompose into two triangles
@ -78,27 +84,30 @@ void FillTriangle(
// New y is the same as y1
float x3 = x0 + (((y1 - y0) / (y2 - y0)) * (x2 - x0));
float y3 = y1;
float z3 = z1;
FillTriangleFlatBottom(buffer, width, color, x0, y0, x1, y1, x3, y3);
FillTriangleFlatTop(buffer, width, color, x1, y1, x3, y3, x2, y2);
FillTriangleFlatBottom(buffer, width, zbuffer, color, x0, y0, z0, x1, y1, z1, x3, y3, z3);
FillTriangleFlatTop(buffer, width, zbuffer, color, x1, y1, z1, x3, y3, z3, x2, y2, z2);
}
}
// PRIVATE FUNCTIONS
static void FillTriangleFlatBottom(
uint32_t *buffer, int width, uint32_t color,
float x0, float y0,
float x1, float y1,
float x2, float y2)
uint32_t *buffer, int width,
float *zbuffer, uint32_t color,
float x0, float y0, float z0,
float x1, float y1, float z1,
float x2, float y2, float z2)
{
if (x2 < x1)
{
float temp;
SWAP(x1, x2, temp);
SWAP(x2, x1, temp);
SWAP(y2, y1, temp);
SWAP(z2, z1, temp);
}
// Top-left fill convention
float dxdy_left = (x1 - x0) / (y1 - y0);
float dxdy_right = (x2 - x0) / (y2 - y0);
@ -108,35 +117,62 @@ static void FillTriangleFlatBottom(
float xEnd = x0 + dxdy_right * (yStart - y0);
// Inverse z-buffering
float z0Inv = 1.0f / z0;
float z1Inv = 1.0f / z1;
float z2Inv = 1.0f / z2;
float dzdy_left = (z1Inv - z0Inv) / (y1 - y0);
float dzdy_right = (z2Inv - z0Inv) / (y2 - y0);
float zStart = z0Inv;
float zEnd = z0Inv;
// Fill
for (int y = yStart; y <= yEnd; ++y)
{
float dzdx = (zEnd - zStart) / (xEnd - xStart);
float z = zStart;
int xStartInt = (int)xStart;
int xEndInt = (int)xEnd;
for (int x = xStartInt; x <= xEndInt; ++x)
{
int pixel = (y * width) + x;
if (z > zbuffer[pixel])
{
DrawPixel(buffer, width, color, x, y);
zbuffer[pixel] = z;
}
z += dzdx;
}
xStart += dxdy_left;
xEnd += dxdy_right;
zStart += dzdy_left;
zEnd += dzdy_right;
}
}
static void FillTriangleFlatTop(
uint32_t *buffer, int width, uint32_t color,
float x0, float y0,
float x1, float y1,
float x2, float y2)
uint32_t *buffer, int width,
float *zbuffer, uint32_t color,
float x0, float y0, float z0,
float x1, float y1, float z1,
float x2, float y2, float z2)
{
if (x1 < x0)
{
float temp;
SWAP(x1, x0, temp);
SWAP(y1, y0, temp);
SWAP(z1, z0, temp);
}
// Top-left fill convention
float dxdy_left = (x2 - x0) / (y2 - y0);
float dxdy_right = (x2 - x1) / (y2 - y1);
@ -146,19 +182,43 @@ static void FillTriangleFlatTop(
float xEnd = x1 + dxdy_right * (yStart - y0);
// Inverse z-buffering
float z0Inv = 1.0f / z0;
float z1Inv = 1.0f / z1;
float z2Inv = 1.0f / z2;
float dzdy_left = (z2Inv - z0Inv) / (y2 - y0);
float dzdy_right = (z2Inv - z1Inv) / (y2 - y1);
float zStart = z0Inv;
float zEnd = z1Inv;
// Fill
for (int y = yStart; y <= yEnd; ++y)
{
float dzdx = (zEnd - zStart) / (xEnd - xStart);
float z = zStart;
int xStartInt = (int)xStart;
int xEndInt = (int)xEnd;
for (int x = xStartInt; x <= xEndInt; ++x)
{
int pixel = (y * width) + x;
if (z > zbuffer[pixel])
{
DrawPixel(buffer, width, color, x, y);
zbuffer[pixel] = z;
}
z += dzdx;
}
xStart += dxdy_left;
xEnd += dxdy_right;
zStart += dzdy_left;
zEnd += dzdy_right;
}
}

3
src/main.cpp
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@ -29,7 +29,8 @@ int main(int argc, char *argv[])
if (result == PLATFORM_OK)
{
Engine_Buffer buffer = {};
buffer.pixels = (uint32_t*)platform.surface->pixels;
buffer.buffer = (uint32_t*)platform.surface->pixels;
buffer.zbuffer = (float*)calloc((size_t)(platform.surface->w * platform.surface->h), sizeof(float));
buffer.width = platform.surface->w;
buffer.height = platform.surface->h;