Fragment shader

add_20.frag

#version 120

void main(){
	//this is the fragment shader
	//this is where the pixel level drawing happens
	//gl_FragCoord gives us the x and y of the current pixel its drawing
	

	gl_FragColor.r = gl_Color.r + 20;
	gl_FragColor.g = gl_Color.g + 20;
	gl_FragColor.b = gl_Color.b + 20;

}