#version 420
 
layout(triangles) in;
layout (triangle_strip, max_vertices=6) out;
 
layout (std140) uniform Matrices {
    mat4 projModelViewMatrix;
    mat3 normalMatrix;
};
 
in VertexData {
    vec2 texCoord;
    vec3 normal;
} VertexIn[];
 
out VertexData {
    vec2 texCoord;
    vec3 normal;
} VertexOut;
 
void main()
{
  for(int i = 0; i < gl_in.length(); i++)
  {
     // copy attributes
    gl_Position = projModelViewMatrix * gl_in[i].gl_Position;
    VertexOut.normal = normalize(normalMatrix * VertexIn[i].normal);
    VertexOut.texCoord = VertexIn[i].texCoord;
 
    // done with the vertex
    EmitVertex();
  }
  EndPrimitive();
 
  for(int i = 0; i < gl_in.length(); i++)
  {
     // copy attributes and displace copy
    gl_Position = projModelViewMatrix * (gl_in[i].gl_Position + vec4(20.0, 0.0, 0.0, 0.0));
    VertexOut.normal = normalize(normalMatrix * VertexIn[i].normal);
    VertexOut.texCoord = VertexIn[i].texCoord;
 
    // done with the vertex
    EmitVertex();
  }
  EndPrimitive();
}