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@ -1,6 +1,8 @@
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#include "color.h"
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#include "engine.h"
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#include "geometry.h"
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#include "util.h"
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#include <cstdio>
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// MACROS
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@ -10,215 +12,80 @@
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}
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// PRIVATE PROTOTYPES
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static void FillTriangleFlatBottom(
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uint32_t *buffer, int width,
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float *zbuffer, uint32_t color,
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float x0, float y0, float z0,
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float x1, float y1, float z1,
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float x2, float y2, float z2);
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static void FillTriangleFlatTop(
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uint32_t *buffer, int width,
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float *zbuffer, uint32_t color,
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float x0, float y0, float z0,
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float x1, float y1, float z1,
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float x2, float y2, float z2);
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// PUBLIC FUNCTIONS
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void FillTriangle(
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uint32_t *buffer, int width,
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float *zbuffer, uint32_t color,
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float x0, float y0, float z0,
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float x1, float y1, float z1,
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float x2, float y2, float z2)
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// STRUCTURES
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struct BoundingBox
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{
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// Horizontal or vertical
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if ((FLOAT_EQUAL(x0,x1) && FLOAT_EQUAL(x1, x2))
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|| (FLOAT_EQUAL(y0, y1) && FLOAT_EQUAL(y1, y2)))
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BoundingBox(Point &v0, Point &v1, Point &v2)
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{
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return;
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}
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yMin = MIN(v0.y, MIN(v1.y, v2.y));
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yMax = MAX(v0.y, MAX(v1.y, v2.y));
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// Sort in ascending Y order
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float temp;
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if (y0 > y1)
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{
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SWAP(x0, x1, temp);
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SWAP(y0, y1, temp);
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SWAP(z0, z1, temp);
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xMin = MIN(v0.x, MIN(v1.x, v2.x));
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xMax = MAX(v0.x, MAX(v1.x, v2.x));
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}
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if (y0 > y2)
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{
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SWAP(x0, x2, temp);
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SWAP(y0, y2, temp);
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SWAP(z0, z2, temp);
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}
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float yMin, yMax;
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float xMin, xMax;
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};
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if (y1 > y2)
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{
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SWAP(x1, x2, temp);
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SWAP(y1, y2, temp);
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SWAP(z1, z2, temp);
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}
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static void ComputeBarycenter(float *w, Point &v0, Point &v1, Point &v2, Point &p)
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{
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float area = (v2.x - v0.x) * (v1.y - v0.y) - (v2.y - v0.y) * (v1.x - v0.x);
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// Flat top triangle
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if (FLOAT_EQUAL(y0, y1))
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{
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FillTriangleFlatTop(buffer, width, zbuffer, color, x0, y0, z0, x1, y1, z1, x2, y2, z2);
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}
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float result[3];
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result[0] = (p.x - v1.x) * (v2.y - v1.y) - (p.y - v1.y) * (v2.x - v1.x);
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result[1] = (p.x - v2.x) * (v0.y - v2.y) - (p.y - v2.y) * (v0.x - v2.x);
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result[2] = (p.x - v0.x) * (v1.y - v0.y) - (p.y - v0.y) * (v1.x - v0.x);
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// Flat bottom triangle
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else if (FLOAT_EQUAL(y1, y2))
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{
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FillTriangleFlatBottom(buffer, width, zbuffer, color, x0, y0, z0, x1, y1, z1, x2, y2, z2);
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}
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result[0] /= area;
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result[1] /= area;
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result[2] /= area;
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// Other - decompose into two triangles
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else
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{
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// Calculate x coordinate at point of decomposition using intercept theorem
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// New y is the same as y1
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float x3 = x0 + (((y1 - y0) / (y2 - y0)) * (x2 - x0));
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float y3 = y1;
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float z3 = z1;
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FillTriangleFlatBottom(buffer, width, zbuffer, color, x0, y0, z0, x1, y1, z1, x3, y3, z3);
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FillTriangleFlatTop(buffer, width, zbuffer, color, x1, y1, z1, x3, y3, z3, x2, y2, z2);
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}
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w[0] = result[0];
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w[1] = result[1];
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w[2] = result[2];
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}
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// PRIVATE FUNCTIONS
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static void FillTriangleFlatBottom(
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uint32_t *buffer, int width,
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float *zbuffer, uint32_t color,
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float x0, float y0, float z0,
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float x1, float y1, float z1,
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float x2, float y2, float z2)
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// PUBLIC FUNCTIONS
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void FillTriangle(
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Engine_Buffer &buffer, ColorU32 &color,
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Point &v0, Point &v1, Point &v2)
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{
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if (x2 < x1)
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{
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float temp;
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SWAP(x2, x1, temp);
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SWAP(y2, y1, temp);
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SWAP(z2, z1, temp);
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}
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// Top-left fill convention
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float dxdy_left = (x1 - x0) / (y1 - y0);
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float dxdy_right = (x2 - x0) / (y2 - y0);
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int yStart = (int)ceilf(y0);
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int yEnd = (int)ceilf(y2) - 1;
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float xStart = x0 + dxdy_left * (yStart - y0);
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float xEnd = x0 + dxdy_right * (yStart - y0);
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BoundingBox box(v0, v1, v2);
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int yMin = (int)ceilf(box.yMin);
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int yMax = (int)ceilf(box.yMax) - 1;
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int xMin = (int)ceilf(box.xMin);
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int xMax = (int)ceilf(box.xMax) - 1;
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// Inverse z-buffering
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float z0Inv = 1.0f / z0;
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float z1Inv = 1.0f / z1;
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float z2Inv = 1.0f / z2;
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float dzdy_left = (z1Inv - z0Inv) / (y1 - y0);
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float dzdy_right = (z2Inv - z0Inv) / (y2 - y0);
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float zStart = z0Inv;
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float zEnd = z0Inv;
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// Fill
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for (int y = yStart; y <= yEnd; ++y)
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for (int y = yMin; y <= yMax; ++y)
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{
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float dzdx = (zEnd - zStart) / (xEnd - xStart);
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float z = zStart;
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int xStartInt = (int)xStart;
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int xEndInt = (int)xEnd;
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for (int x = xStartInt; x <= xEndInt; ++x)
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for (int x = xMin; x <= xMax; ++x)
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{
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int pixel = (y * width) + x;
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if (z > zbuffer[pixel])
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{
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DrawPixel(buffer, width, color, x, y);
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zbuffer[pixel] = z;
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}
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z += dzdx;
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}
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xStart += dxdy_left;
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xEnd += dxdy_right;
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zStart += dzdy_left;
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zEnd += dzdy_right;
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}
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}
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Point p(x, y, 1.0f);
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static void FillTriangleFlatTop(
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uint32_t *buffer, int width,
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float *zbuffer, uint32_t color,
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float x0, float y0, float z0,
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float x1, float y1, float z1,
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float x2, float y2, float z2)
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{
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if (x1 < x0)
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{
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float temp;
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SWAP(x1, x0, temp);
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SWAP(y1, y0, temp);
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SWAP(z1, z0, temp);
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}
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float barycenter[3];
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// Top-left fill convention
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float dxdy_left = (x2 - x0) / (y2 - y0);
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float dxdy_right = (x2 - x1) / (y2 - y1);
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int yStart = (int)ceilf(y0);
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int yEnd = (int)ceilf(y2) - 1;
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float xStart = x0 + dxdy_left * (yStart - y0);
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float xEnd = x1 + dxdy_right * (yStart - y0);
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// Inverse z-buffering
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float z0Inv = 1.0f / z0;
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float z1Inv = 1.0f / z1;
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float z2Inv = 1.0f / z2;
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float dzdy_left = (z2Inv - z0Inv) / (y2 - y0);
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float dzdy_right = (z2Inv - z1Inv) / (y2 - y1);
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float zStart = z0Inv;
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float zEnd = z1Inv;
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// Fill
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for (int y = yStart; y <= yEnd; ++y)
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{
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float dzdx = (zEnd - zStart) / (xEnd - xStart);
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float z = zStart;
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ComputeBarycenter(barycenter, v0, v1, v2, p);
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int xStartInt = (int)xStart;
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int xEndInt = (int)xEnd;
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if (barycenter[0] >= 0 && barycenter[1] >= 0 && barycenter[2] >= 0)
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{
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float zInv =
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(barycenter[0] * (1.0f/v0.z))
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+ (barycenter[1] * (1.0f/v1.z))
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+ (barycenter[2] * (1.0f/v2.z));
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for (int x = xStartInt; x <= xEndInt; ++x)
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{
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int pixel = (y * width) + x;
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int pixel = (y * buffer.width + x);
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if (z > zbuffer[pixel])
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{
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DrawPixel(buffer, width, color, x, y);
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if (zInv > buffer.zbuffer[pixel])
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{
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DrawPixel(buffer.buffer, buffer.width, color.u32, x, y);
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zbuffer[pixel] = z;
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buffer.zbuffer[pixel] = zInv;
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}
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}
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z += dzdx;
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}
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xStart += dxdy_left;
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xEnd += dxdy_right;
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zStart += dzdy_left;
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zEnd += dzdy_right;
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}
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}
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