PostcardSizedRaytracer-CodeOutline.cpp

// This is just the outline/summary, full source code here http://fabiensanglard.net/postcard_pathtracer/formatted_full.html
void main() {
  int w = 960, h = 540, samplesCount = 2;

  Vec position(-22, 5, 25);
  Vec goal = !(Vec(-3, 4, 0) + position * -1);
  Vec left = !Vec(goal.z, 0, -goal.x) * (1. / w);

  // Cross-product to get the up vector
  Vec up(goal.y * left.z - goal.z * left.y,
         goal.z * left.x - goal.x * left.z,
         goal.x * left.y - goal.y * left.x);
  
  for (int y = h; y--;) {
    for (int x = w; x--;) {
      Vec color;
      for (int p = samplesCount; p--;) {
        Vec direction = !(goal + left * (x - w / 2 + randomVal()) + up * (y - h / 2 + randomVal()));
        color = color + Trace(position, direction);
        
        // Reinhard tone mapping
        ...
      }
    }
  }
}

Vec Trace(Vec origin, Vec direction) {
  ...
  for (int bounceCount = 3; bounceCount--;) {
    int hitType = RayMarching(origin, direction, sampledPosition, normal);
    ...
  }
}

int RayMarching(Vec origin, Vec direction, Vec &hitPos, Vec &hitNorm) {
  ...
  // Signed distance marching
  for (float total_d=0; total_d < 100; total_d += d)
    if ((d = QueryDatabase(hitPos = origin + direction * total_d, hitType)) < .01
            || ++noHitCount > 99)
  ...
}

float QueryDatabase(Vec position, int &hitType) {
  ..
  
  // Contains several calls to BoxTest(..)
  // Also calls min, sqrtf, fabsf, powf
  // and some of the Vec operators (%, +, etc)
}

float BoxTest(Vec position, Vec lowerLeft, Vec upperRight) {
  // Contains several calls to min(..)
}