#version 430 core

float PI = 3.14159f;

uniform sampler2D colorTexture;

uniform float exposition;

in vec3 vecNormal;
in vec3 worldPos;
in vec2 vtc;

out vec4 outColor;

in vec3 viewDirTS;
in vec3 lightDirTS;
in vec3 sunDirTS;

uniform float u_time;
float pi = 3.14159;
// 2D Random
float random (in vec2 st) {
    return fract(sin(dot(st.xy,
                         vec2(12.9898,78.233)))
                 * 43758.5453123);
}

// 2D Noise based on Morgan McGuire @morgan3d
// https://www.shadertoy.com/view/4dS3Wd
float noise (in vec2 st) {
    vec2 i = floor(st);
    vec2 f = fract(st);

    // Four corners in 2D of a tile
    float a = random(i);
    float b = random(i + vec2(1.0, 0.0));
    float c = random(i + vec2(0.0, 1.0));
    float d = random(i + vec2(1.0, 1.0));
    
    vec2 randA = vec2(a *2.0 *pi);
    vec2 randB = vec2(b *2.0 *pi);
    vec2 randC = vec2(c *2.0 *pi);
    vec2 randD = vec2(d *2.0 *pi);
    
    vec2 offsetA = a-st;
    vec2 offsetB = b-st;
    vec2 offsetC = c-st;
    vec2 offsetD = d-st;
    
    offsetA = offsetA*randA;
    offsetB = offsetB*randB;
    offsetC = offsetC*randC;
    offsetD = offsetD*randD;
    
    float resA = smoothstep(offsetA.x,offsetA.y, f.y);
    float resB = smoothstep(offsetB.x,offsetB.y, f.y);
    float resC = smoothstep(offsetC.x,offsetC.y, f.y);
    float resD = smoothstep(offsetD.x,offsetD.y, f.y);

	vec2 u = smoothstep(0.,1.,f);


    float ab= mix(a, b, u.x);
    float cd = mix(c, d, u.x);
    return mix(ab,cd,u.y);
  
}

void main()
{

    vec2 st = vtc;
    vec2 pos = vec2(st*3.776);

    // Use the noise function
    float n = 1.836 * 0.676*noise(pos*2.576);
    n = smoothstep(-0.096, 1.176, n);

	outColor = vec4(vec3(n), 1);
}