Untitled

#version 400

in vec2 coord;

uniform vec3 color;
uniform sampler2D depthMap;
uniform sampler2D thicknessMap;
uniform sampler2D normalMap;
uniform vec2 screenSize;
uniform mat4 projection;
uniform mat4 mView;
uniform vec3 lightPos;
uniform float zNear;
uniform float zFar;

out vec4 fragColor;

const vec3 lightDir = vec3(.5, .5, .5);
const float shininess = 300.0;
const vec3 specularColor = vec3(1.0, 1.0, 1.0);
const float fresPower = 0.1f;
const float fresScale = 0.1;
const float fresBias = 0.1;
const vec3 thicknessRefraction = vec3(0.02, 0.03, 0.06);

float linearizeDepth(float depth) {
        return (2.0 * zNear) / (zFar + zNear - depth * (zFar - zNear));
}

vec3 uvToEye(vec2 p, float z) {
        vec2 pos = p * 2.0f - 1.0f;
        vec4 clipPos = vec4(pos, z, 1.0f);
        vec4 viewPos = inverse(projection) * clipPos;
        return viewPos.xyz / viewPos.w;
}

void main() {
    float depth = texture(depthMap, coord).x;
    depth = linearizeDepth(depth);
    if (depth >= .99f) {
        fragColor = vec4(1.0f);
        return;
     }

    vec3 pos = uvToEye(coord, depth);

        vec3 normal = texture(normalMap, coord).xyz;

    //Diffuse light
    float diffuse = dot(normal, lightDir) * 0.5f + 0.5f;

    //Phong specular
    vec3 viewDir = normalize(-pos);
    vec3 halfVec = normalize(viewDir + lightDir);
    float specular = pow(max(0.0f, dot(normal, halfVec)), shininess);

    //Fresnel
    //float fresnel = fresBias + fresScale * pow(1.0f - max(0.0f, dot(normal, viewDir)), fresPower);

    //Color from absorption
    float thickness = texture(thicknessMap, coord).x;
    vec3 cBeer = vec3(exp(-.05*thickness), exp(-.05*thickness), exp(-.05*thickness));
    vec3 absorbColor = color * cBeer;

    float alpha = min(dot(cBeer, cBeer), 0.8);

    //Compositing everything
    vec4 finalColor = vec4(absorbColor + diffuse*specularColor.xyz*specular, alpha);

        fragColor = vec4(finalColor);

        gl_FragDepth = depth;
}