message: fixed point.vert for texture-based size
diff: @@ -17,6 +17,10 @@ uniform float uViewportHeight;
  uniform float uSize;
  #elif defined(dSizeType_attribute)
  attribute float aSize;
  +#elif defined(dSizeType_instance) || defined(dSizeType_group) || defined(dSizeType_groupInstance)
  + varying vec4 vSize;
  + uniform vec2 uSizeTexDim;
  + uniform sampler2D tSize;
  #endif
  attribute vec3 aPosition;
  