uniform mat4 ModelViewProjectionMatrix;
#ifdef USE_WORLD_CLIP_PLANES
uniform mat4 ModelMatrix;
#endif
uniform float size;
uniform float outlineWidth;

in vec3 pos;
out vec4 radii;

void main()
{
  vec4 pos_4d = vec4(pos, 1.0);
  gl_Position = ModelViewProjectionMatrix * pos_4d;
  gl_PointSize = size;

  /* calculate concentric radii in pixels */
  float radius = 0.5 * size;

  /* start at the outside and progress toward the center */
  radii[0] = radius;
  radii[1] = radius - 1.0;
  radii[2] = radius - outlineWidth;
  radii[3] = radius - outlineWidth - 1.0;

  /* convert to PointCoord units */
  radii /= size;

#ifdef USE_WORLD_CLIP_PLANES
  world_clip_planes_calc_clip_distance((ModelMatrix * pos_4d).xyz);
#endif
}