#version 430 core
layout (points) in;
layout (triangle_strip, max_vertices = 4) out;
layout (std140, binding = 0) uniform TheMat { mat4 theMat; } ;
uniform vec3 lightPos;
uniform vec4 lumRad;
out vec3 dField;
out vec3 lum;
float isLHS (vec2 startV, vec2 testV)
{ return sign( -startV.x * testV.y + startV.y * testV.x); }
void main()
{
vec4 p1 = vec4 (gl_in[0].gl_Position.xy,0,1);
vec4 p2 = vec4 (gl_in[0].gl_Position.zw,0,1);
if (isLHS (p1.xy - lightPos.xy, p2.xy - lightPos.xy) < 0)
{ lum = lumRad.rgb;
  float rad = lumRad.a;
  vec4 p3 = vec4 (p1.xy,100,1);
  vec4 p4 = vec4 (p2.xy,100,1);
  vec2 d1 = p1.xy - lightPos.xy;
  vec2 d2 = p2.xy - lightPos.xy;
  vec4 a1 = theMat * p1;
  vec4 a2 = theMat * p2;
  vec4 a3 = theMat * p3;
  vec4 a4 = theMat * p4;
  dField = (p1.xyz - lightPos) / rad; gl_Position = a1; EmitVertex();
  dField = (p3.xyz - lightPos) / rad; gl_Position = a3; EmitVertex();
  dField = (p2.xyz - lightPos) / rad; gl_Position = a2; EmitVertex();
  dField = (p4.xyz - lightPos) / rad; gl_Position = a4; EmitVertex();
  EndPrimitive();
} else {}
}
