#version 430 core
layout (points) in;
layout (triangle_strip, max_vertices = 4) out;
void main()
{
  gl_Position = vec4 (1,1,0.9,1);
  EmitVertex();
  gl_Position = vec4 (1,-1,0.9,1);
  EmitVertex();
  gl_Position = vec4 (-1,1,0.9,1);
  EmitVertex();
  gl_Position = vec4 (-1,-1,0.9,1);
  EmitVertex();
  EndPrimitive();
}