#version 430 core

uniform vec3 lightDir;
uniform vec2 resolution;

in vec3 interpNormal;
in vec3 localPos;

float random2d(in vec2 point) {
	return fract(sin(dot(point.xy, vec2(12.9898, 78.233))) * 43758.5453123);
}

float perlinNoise(in vec2 point) {
	vec2 i = floor(point);
	vec2 f = fract(point);
	
	float corn1 = random2d(i);
	float corn2 = random2d(i + vec2(1.0, 0.0));
	float corn3 = random2d(i + vec2(0.0, 1.0));
	float corn4 = random2d(i + vec2(1.0, 1.0));
	
	//interpolacja Hermite'a
	vec2 u = f * f *(3.0 - 2.0 * f);
	
	float p1 = mix(corn1, corn2, u.x);
	float p2 = (corn3 - corn1) * u.y * (1.0 - u.x);
	float p3 = (corn4 - corn2) * u.x * u.y;
	
	return p1 + p2 + p3;
}

void main()
{
	vec3 normal = normalize(interpNormal);
	float diffuse = max(dot(normal, -lightDir), 0.0);

	vec2 point = gl_FragCoord.xy / resolution.xy + localPos.xy;
	vec2 pos = vec2(point * 0.3);
	
	float noise = perlinNoise(pos);
	vec3 color = (vec3(noise) * 2) * vec3(0.57, 0.55, 0.18);
	
	//gl_FragColor = vec4(vec3(color), 1.0);
	gl_FragColor = vec4(color.x * diffuse, color.y * diffuse, color.z * diffuse, 1.0);
	
	
	
	//if(sin(localPos.y) > 0) gl_FragColor = vec4(positiveColor.x * diffuse, positiveColor.y * diffuse, positiveColor.z * diffuse, 1.0);
	//else gl_FragColor = vec4(negativeColor.x * diffuse, negativeColor.y * diffuse, negativeColor.z * diffuse, 1.0);
}