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

in vec4 vBackPoss[];
uniform vec2 lightPos;

void main()
{
  vec2 posa = gl_in[0].gl_Position.xy;
  vec2 posb = gl_in[0].gl_Position.zw;
  vec2 v = normalize( posb - posa);
  vec2 off = vec2( -(v.y *0.2) 
                 , v.x *0.2 );

  gl_Position = vec4 (posa, 0 , 1);
  EmitVertex();
  gl_Position = vec4 (posb, 0 , 1);
  EmitVertex();
  gl_Position = vec4 (posa + off, 0 , 1);
  EmitVertex();
  gl_Position = vec4 (posb + off, 0 , 1);
  EmitVertex();

  EndPrimitive();
}