#version 120

attribute vec2 z;
uniform float rotation_angle;

void main()
{
  float x = z.x * cos(z.y);
  float y = z.x * sin(z.y);
  gl_Position.x = x * cos(rotation_angle) - y * sin(rotation_angle);
  gl_Position.y = x * sin(rotation_angle) + y * cos(rotation_angle);
  gl_Position.z = 0.;
  gl_Position.w = 1.;
  gl_PointSize = 32.;
}