#version 430 core
layout (points) in;
layout (triangle_strip, max_vertices = 4) out;
out float lum;
out vec2 dField;

uniform vec2 winSize;
uniform float zoom;
uniform mat4 worldMat;

void main()
{
  lum = gl_in[0].gl_Position.w;
  vec4 cenPos = worldMat * vec4( gl_in[0].gl_Position.xy, 0 , 1);
  float gRad = gl_in[0].gl_Position.z * zoom * 2;

  dField = vec2 ( 1, 1);
  gl_Position 
      = vec4 (cenPos.x + gRad/winSize.x, cenPos.y + gRad/winSize.y, -0 , 1);
  EmitVertex();
  dField = vec2 (-1, 1);
  gl_Position 
      = vec4 (cenPos.x - gRad/winSize.x, cenPos.y + gRad/winSize.y, -0 , 1);
  EmitVertex();
  dField = vec2 ( 1,-1);
  gl_Position 
      = vec4 (cenPos.x + gRad/winSize.x, cenPos.y - gRad/winSize.y, -0 , 1);
  EmitVertex();
  dField = vec2 (-1,-1);
  gl_Position 
      = vec4 (cenPos.x - gRad/winSize.x, cenPos.y - gRad/winSize.y, -0 , 1);
  EmitVertex();

  EndPrimitive();
}