threejs_clouds_geom_inst_vertex.glsl

attribute vec4 instancePosition;
attribute float instanceAngle;

varying vec2 vUV;

void main(){
  vUV = uv;

  vec3 rotatedPosition = position;
  rotatedPosition.x = cos( instanceAngle ) * position.x - sin( instanceAngle ) * position.y;
  rotatedPosition.y = sin( instanceAngle ) * position.x + cos( instanceAngle ) * position.y;
  float scale = instancePosition.w;
  rotatedPosition *= scale;

  vec4 mvPosition = modelViewMatrix * vec4(instancePosition.xyz, 1);
  mvPosition.xyz += rotatedPosition;
  
  gl_Position = projectionMatrix * mvPosition;
}