#version 400 compatibility
#extension GL_EXT_gpu_shader4: enable
#extension GL_EXT_geometry_shader4: enable

layout( triangles )  in;
layout( triangle_strip, max_vertices=200 )  out;

uniform float uShrink;

in vec3 vNormal[3];

out float gLightIntensity;

const vec3 LIGHTPOS = vec3( 0., 10., 0. );

vec3 V[3];
vec3 CG;

void
ProduceVertex( int v )
{
	gLightIntensity  = abs( dot( normalize(LIGHTPOS - V[v]), vNormal[v] ) );

	gl_Position = uProjectionMatrix * vec4( CG + uShrink * ( V[v] - CG ), 1. );
	EmitVertex( );
}



void
main( )
{
	V[0]  =   gl_PositionIn[0].xyz;
	V[1]  =   gl_PositionIn[1].xyz;
	V[2]  =   gl_PositionIn[2].xyz;

	CG =( V[0] + V[1] + V[2] ) / 3.;

	ProduceVertex( 0 );
	ProduceVertex( 1 );
	ProduceVertex( 2 );
}