#version 460
layout(quads) in;
uniform mat4 mvp;
out vec2 f_texcoord;

//quad interpol
vec4 interpolate(in vec4 v0, in vec4 v1, in vec4 v2, in vec4 v3)
{
	vec4 a = mix(v0, v1, gl_TessCoord.x);
	vec4 b = mix(v3, v2, gl_TessCoord.x);
	return mix(a, b, gl_TessCoord.y);
}

vec4 n4_test(vec4 p){
	vec3 offset = p.xyz;
	return vec4(0.5 * (normalize(offset) + p.xyz), 1);
}

void main(){

	vec4 pre_normalize_position = interpolate(
			gl_in[0].gl_Position, 
			gl_in[1].gl_Position, 
			gl_in[2].gl_Position, 
			gl_in[3].gl_Position);

	gl_Position = mvp * pre_normalize_position;

	f_texcoord = g_texcoord
}