gistfile1.d

  WorldObject[auto~] inRect(vec2f a, b) {
    auto world-center = vec3f(0), world-radius = 1;
    auto center = cam.apply(world-center).xy;
    float radius;
    using glModelviewMatrix {
      cam.unrotate;
      auto offset = cam.apply(world-center + world-radius * vec3f.X).xy - center;
      radius = |offset|;
    }
    auto aspect = vec2f(1, 1/cam.aspect);
    if (overlaps_rect_circle(a*aspect, b*aspect, center*aspect, radius)) {
      WorldObject[auto~] res; res ~= this; return res;
    }
    return null;
  }