1
0
Fork 0

Add triangle filling with a solid color

master
Austin Morlan 4 years ago
parent 33cb124d77
commit f642b0ec02
Signed by: austin
GPG Key ID: FD6B27654AF5E348
  1. 4
      Makefile
  2. 25
      include/color.h
  3. 10
      include/geometry.h
  4. 10
      src/engine.cpp
  5. 164
      src/geometry.cpp

@ -36,10 +36,10 @@ WARNINGS_OFF=-Wno-missing-braces -Wno-gnu-anonymous-struct -Wno-old-style-cast\
CFLAGS=$(D) $(O) -std=c++11 $(WARNINGS_ON) $(WARNINGS_OFF) -I$(INCLUDE_DIR)
LIBS=-lSDL2
_HEADERS = engine.h geometry.h loader.h platform.h point.h transform.h util.h
_HEADERS = color.h engine.h geometry.h loader.h platform.h point.h transform.h util.h
HEADERS = $(patsubst %,$(INCLUDE_DIR)/%,$(_HEADERS))
_OBJS = engine.o loader.o main.o platform.o transform.o
_OBJS = engine.o geometry.o loader.o main.o platform.o transform.o
OBJS = $(patsubst %,$(BUILD_DIR)/%,$(_OBJS))
$(BUILD_DIR)/%.o: $(SRC_DIR)/%.cpp $(HEADERS)

@ -0,0 +1,25 @@
#ifndef COLOR_H
#include <cstdint>
struct ColorU32
{
union
{
struct
{
uint8_t b;
uint8_t g;
uint8_t r;
uint8_t a;
};
uint32_t u32;
};
};
#define COLOR_H
#endif

@ -1,9 +1,11 @@
#ifndef GEOMETRY_H
#include "point.h"
#include <cstdint>
#include <vector>
// STRUCTURES
struct Face
{
unsigned int vertIndex[3];
@ -33,6 +35,14 @@ 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);
#define GEOMETRY_H
#endif

@ -1,5 +1,7 @@
#include "camera.h"
#include "color.h"
#include "engine.h"
#include "geometry.h"
#include "loader.h"
#include "matrix.h"
#include "transform.h"
@ -73,6 +75,14 @@ void Engine_Render(Engine_Buffer &buffer, uint32_t input)
unsigned int v0 = mesh.faces[f].vertIndex[0];
unsigned int v1 = mesh.faces[f].vertIndex[1];
unsigned int v2 = mesh.faces[f].vertIndex[2];
ColorU32 white = {0xff,0xff,0xff,0xff};
FillTriangle(
buffer.pixels, buffer.width, white.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);
}
}

@ -0,0 +1,164 @@
#include "color.h"
#include "geometry.h"
#include "util.h"
// MACROS
#define DrawPixel(buffer, width, color, x, y)\
{\
buffer[width * y + x] = color;\
}
// 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);
static void FillTriangleFlatTop(
uint32_t *buffer, int width, uint32_t color,
float x0, float y0,
float x1, float y1,
float x2, float y2);
// PUBLIC FUNCTIONS
void FillTriangle(
uint32_t *buffer, int width, uint32_t color,
float x0, float y0,
float x1, float y1,
float x2, float y2)
{
// Horizontal or vertical
if ((FLOAT_EQUAL(x0,x1) && FLOAT_EQUAL(x1, x2))
|| (FLOAT_EQUAL(y0, y1) && FLOAT_EQUAL(y1, y2)))
{
return;
}
// Sort in ascending Y order
float temp;
if (y0 > y1)
{
SWAP(x0, x1, temp);
SWAP(y0, y1, temp);
}
if (y0 > y2)
{
SWAP(x0, x2, temp);
SWAP(y0, y2, temp);
}
if (y1 > y2)
{
SWAP(x1, x2, temp);
SWAP(y1, y2, temp);
}
// Flat top triangle
if (FLOAT_EQUAL(y0, y1))
{
FillTriangleFlatTop(buffer, width, color, x0, y0, x1, y1, x2, y2);
}
// Flat bottom triangle
else if (FLOAT_EQUAL(y1, y2))
{
FillTriangleFlatBottom(buffer, width, color, x0, y0, x1, y1, x2, y2);
}
// Other - decompose into two triangles
else
{
// Calculate x coordinate at point of decomposition using intercept theorem
// New y is the same as y1
float x3 = x0 + (((y1 - y0) / (y2 - y0)) * (x2 - x0));
float y3 = y1;
FillTriangleFlatBottom(buffer, width, color, x0, y0, x1, y1, x3, y3);
FillTriangleFlatTop(buffer, width, color, x1, y1, x3, y3, x2, y2);
}
}
// 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)
{
if (x2 < x1)
{
float temp;
SWAP(x1, x2, temp);
}
// Top-left fill convention
float dxdy_left = (x1 - x0) / (y1 - y0);
float dxdy_right = (x2 - x0) / (y2 - y0);
int yStart = (int)ceilf(y0);
int yEnd = (int)ceilf(y2) - 1;
float xStart = x0 + dxdy_left * (yStart - y0);
float xEnd = x0 + dxdy_right * (yStart - y0);
// Fill
for (int y = yStart; y <= yEnd; ++y)
{
int xStartInt = (int)xStart;
int xEndInt = (int)xEnd;
for (int x = xStartInt; x <= xEndInt; ++x)
{
DrawPixel(buffer, width, color, x, y);
}
xStart += dxdy_left;
xEnd += dxdy_right;
}
}
static void FillTriangleFlatTop(
uint32_t *buffer, int width, uint32_t color,
float x0, float y0,
float x1, float y1,
float x2, float y2)
{
if (x1 < x0)
{
float temp;
SWAP(x1, x0, temp);
}
// Top-left fill convention
float dxdy_left = (x2 - x0) / (y2 - y0);
float dxdy_right = (x2 - x1) / (y2 - y1);
int yStart = (int)ceilf(y0);
int yEnd = (int)ceilf(y2) - 1;
float xStart = x0 + dxdy_left * (yStart - y0);
float xEnd = x1 + dxdy_right * (yStart - y0);
// Fill
for (int y = yStart; y <= yEnd; ++y)
{
int xStartInt = (int)xStart;
int xEndInt = (int)xEnd;
for (int x = xStartInt; x <= xEndInt; ++x)
{
DrawPixel(buffer, width, color, x, y);
}
xStart += dxdy_left;
xEnd += dxdy_right;
}
}
Loading…
Cancel
Save