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Base rasterizer

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augustin64 2025-02-05 11:24:50 +01:00
parent e549cb866a
commit d5616ba9d3
1 changed files with 72 additions and 12 deletions
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82
image-processing/3-Rasterization/c++/rasterizer.cpp
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@ -12,32 +12,92 @@
//Global flag to silent verbose messages
bool silent;
typedef struct point {
int x, y;
} point_t;
typedef struct triangle {
point_t p, q, r;
} triangle_t;
void print_triangle(triangle_t t) {
printf("(%d %d) (%d %d) (%d %d)", t.p.x, t.p.y, t.q.x, t.q.y, t.r.x, t.r.y);
}
int sig(int x) {
return (x != 0) * (x > 0 ? 1 : -1);
}
int dist(point_t p, point_t q) {
return sqrt((p.x-q.x)*(p.x-q.x) + (p.y-q.y)*(p.y-q.y));
}
int determinant(point_t p, point_t q, point_t r) {
int a, b, c, d;
a = q.x-p.x;
b = q.y-p.y;
c = r.x-p.x;
d = r.y-p.y;
return a*d - b*c;
}
unsigned char isInside(point_t a, triangle_t t) {
/* returns : 0 is not inside, 1 if inside, 2 if on edge */
int det_a1 = determinant(a, t.q, t.r);
int det_a2 = determinant(a, t.p, t.q);
int det_a3 = determinant(a, t.r, t.p);
if ((sig(det_a1)==sig(det_a2)) && (sig(det_a1)==sig(det_a3))) {
int dist_t1 = dist(t.q, t.r)*1.5;
int dist_t2 = dist(t.p, t.q)*1.5;
int dist_t3 = dist(t.r, t.p)*1.5;
if ((dist_t1 > abs(det_a1)) || (dist_t2 > abs(det_a2)) || (dist_t3 > abs(det_a3))) return 2;
return 1;
};
return 0;
}
int main(int argc, char **argv)
{
CLI::App app{"rasterizer"};
std::string outputImage= "output.png";
app.add_option("-o,--output", outputImage, "Output image")->required();
unsigned int nbTriangles = 5;
app.add_option("-n,--ntriangles", nbTriangles, "Number of triangles (5)");
CLI11_PARSE(app, argc, argv);
srand(time(0));
//Image loading
int width=640,height=480, nbChannels=3;
std::vector<unsigned char> output(width*height*nbChannels);
int* colors = (int*)malloc(sizeof(int)*3*nbTriangles);
triangle_t* t = (triangle_t*)malloc(sizeof(triangle_t)*nbTriangles);
for (auto i=0; i < nbTriangles; i++) {
t[i] = {rand()%width, rand()%height, rand()%width, rand()%height, rand()%width, rand()%height};
colors[3*i] = rand()%255;
colors[3*i+1] = rand()%255;
colors[3*i+2] = rand()%255;
print_triangle(t[i]);
printf(" : (%d, %d, %d)\n", colors[3*i], colors[3*i+1], colors[3*i+2]);
}
for(auto i = 0 ; i < width ; ++i)
{
for(auto j = 0; j < height; ++j)
{
for(auto i = 0 ; i < width ; ++i) {
for(auto j = 0; j < height; ++j) {
auto indexPixel = nbChannels*(width*j+i);
unsigned char r = 0;
unsigned char g = 0;
unsigned char b = 0;
//Swapping the channels
output[ indexPixel ] = b;
output[ indexPixel + 1 ] = g;
output[ indexPixel + 2 ] = r;
output[indexPixel] = output[indexPixel+1] = output[indexPixel+2] = 0;
for (auto triangle_id=0; triangle_id < nbTriangles; triangle_id++) {
int valid = isInside({i, j}, t[triangle_id]);
if (valid == 1) {
output[ indexPixel ] = colors[3*triangle_id];
output[ indexPixel + 1 ] = colors[3*triangle_id+1];
output[ indexPixel + 2 ] = colors[3*triangle_id+2];
} else if (valid == 2) {
output[indexPixel] = output[indexPixel+1] = output[indexPixel+2] = 255;
}
}
}
}