uniform mat4 ViewProjectionMatrix;
#ifdef USE_WORLD_CLIP_PLANES
uniform mat4 ModelMatrix;
#endif
uniform vec3 screen_vecs[2];

/* ---- Instantiated Attrs ---- */
in vec3 pos; /* using Z as axis id */

/* ---- Per instance Attrs ---- */
in mat4 InstanceModelMatrix;
in vec3 color;
in float size;

flat out vec4 finalColor;

void main()
{
  vec3 offset = vec3(0.0);

#ifdef AXIS_NAME
  if (pos.z == 0.0) {
    offset = vec3(1.125, 0.0, 0.0);
  }
  else if (pos.z == 1.0) {
    offset = vec3(0.0, 1.125, 0.0);
  }
  else {
    offset = vec3(0.0, 0.0, 1.125);
  }
  offset *= size;
#endif

  vec3 screen_pos = screen_vecs[0].xyz * pos.x + screen_vecs[1].xyz * pos.y;
  vec4 pos_4d = InstanceModelMatrix * vec4(offset, 1.0) + vec4(screen_pos * size, 0.0);
  gl_Position = ViewProjectionMatrix * pos_4d;
  finalColor = vec4(color, 1.0);

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