#include<graphics.h>#include<conio.h>#include <math.h> // fminf(), sinf(), cosf(), sqrt()#include <stdlib.h> // rand(), RAND_MAX
#define TWO_PI 6.28318530718f#define W 512#define H 512#define N 64#define MAX_STEP 64#define MAX_DISTANCE 2.0f#define EPSILON 1e-6f
typedef struct { float sd, emissive; } Result;
unsigned char img[W * H * 3];
float circleSDF(float x, float y, float cx, float cy, float r) { float ux = x - cx, uy = y - cy; return sqrtf(ux * ux + uy * uy) - r;}
Result unionOp(Result a, Result b) { return a.sd < b.sd ? a : b;}
Result intersectOp(Result a, Result b) { Result r = a.sd > b.sd ? b : a; r.sd = a.sd > b.sd ? a.sd : b.sd; return r;}
Result subtractOp(Result a, Result b) { Result r = a; r.sd = (a.sd > -b.sd) ? a.sd : -b.sd; return r;}
Result complementOp(Result a) { a.sd = -a.sd; return a;}
Result scene(float x, float y) {#if 0 Result r1 = { circleSDF(x, y, 0.3f, 0.3f, 0.10f), 2.0f }; Result r2 = { circleSDF(x, y, 0.3f, 0.7f, 0.05f), 0.8f }; Result r3 = { circleSDF(x, y, 0.7f, 0.5f, 0.10f), 0.0f }; return unionOp(unionOp(r1, r2), r3);#else Result a = { circleSDF(x, y, 0.4f, 0.5f, 0.20f), 1.0f }; Result b = { circleSDF(x, y, 0.6f, 0.5f, 0.20f), 0.8f }; return subtractOp(b, a);#endif}
float trace(float ox, float oy, float dx, float dy) { float t = 0.001f; for (int i = 0; i < MAX_STEP && t < MAX_DISTANCE; i++) { Result r = scene(ox + dx * t, oy + dy * t); if (r.sd < EPSILON) return r.emissive; t += r.sd; } return 0.0f;}
float sample(float x, float y) { float sum = 0.0f; for (int i = 0; i < N; i++) { float a = TWO_PI * (i + (float)rand() / RAND_MAX) / N; sum += trace(x, y, cosf(a), sinf(a)); } return sum / N;}
int main() { initgraph(W,H); unsigned char* p = img; for (int y = 0; y < H; y++) { for (int x = 0; x < W; x++, p += 3) { p[0] = p[1] = p[2] = (int)(fminf(sample((float)x / W, (float)y / H) * 255.0f, 255.0f)); putpixel(x,y,RGB(p[0],p[1],p[2])); } } _getch();}
