#version 120
#extension GL_EXT_gpu_shader4 : require 
 
uniform sampler2DRect matrixTexture;
uniform sampler2DRect colorTexture;
uniform mat4 mvpMatrix;

void main(){

	float y = 0;
	float x = gl_InstanceID*4;
    
    mat4 transformMatrix = mat4( 
    	texture2DRect(matrixTexture, vec2((x+0.5), y+0.5)),
    	texture2DRect(matrixTexture, vec2((x+1.5), y+0.5)),
    	texture2DRect(matrixTexture, vec2((x+2.5), y+0.5)), 
    	texture2DRect(matrixTexture, vec2((x+3.5), y+0.5)));

	// Multiply the shape coordinates by the transformation matrix
    // Offset by the position
    vec4 vPos = transformMatrix *  gl_Vertex; 

	// Set the front color to the color passed through with glColor
	gl_FrontColor = texture2DRect(colorTexture, vec2((gl_InstanceID+0.5), 0.5));
    gl_BackColor = gl_FrontColor;
    
	// Multiply by the model view and projection matrix
	gl_Position = mvpMatrix * vPos;
}