#version 150

uniform sampler2D tex;
uniform sampler2D etex;
uniform sampler2D stex;
uniform sampler2D ntex;
uniform vec3 lightPos;
uniform vec3 eyePos;
uniform float roughness;

in vec2 v_texcoord;
in vec3 v_normal;
in vec3 v_tangent;
in vec3 v_objPos;
in vec3 v_worldPos;
in mat4 v_worldMatrix;

out vec4 color;

void main(){
    vec3 N = normalize(v_normal);
    vec4 q = texture(ntex, v_texcoord);
    q = (q - (1/2.0)) * 2.0;
    vec3 T = normalize(v_tangent);
    vec3 B = cross(N,T);
    mat3 Q = mat3(T.x, B.x, N.x, T.y, B.y, N.y, T.z, B.z, N.z);
    vec3 newNormal = q.rgb * Q;
    newNormal = normalize(newNormal);
    newNormal = (vec4(newNormal,0) * v_worldMatrix).xyz;
    vec3 L = normalize(lightPos - v_worldPos);
    vec3 V = normalize(eyePos - v_worldPos);
    vec3 R = reflect( -L,newNormal);
    float diffuse = clamp( dot(newNormal,L), 0.0, 1.0 );

     float dp = clamp( dot(L,N) , 0.0, 1.0);

    //float specular = pow( max( 0.0, dot(V,R)) , 32.0 ); //hardcoded exponent
    //specular *= sign(diffuse);  //no specular if no diffuse

    //Cook-Torrance Specular:
    vec3 specmtl = texture(stex, v_texcoord).rgb;
    vec3 specular;
    float r = roughness;
    vec3 one = vec3(1.0);
    vec3 H = normalize(0.5*(L+V));
    vec3 sp = min( specmtl, vec3(0.95));
    vec3 sqrtk = sqrt(sp);
    vec3 n = (-one - sqrtk) / (sqrtk - one);
    vec3 cos_a = vec3(dot(N,V));
    vec3 cos_b = vec3(dot(N,L));
    vec3 cos_c = vec3(dot(V,H));
    vec3 cos_d = vec3(dot(N,H));
    vec3 q2 = sqrt(cos_c*cos_c - one + n*n);
    vec3 f1 = q2 - cos_c;
    vec3 f2 = q2 + cos_c;
    vec3 f3 = (f2 * cos_c)-one;
    vec3 f4 = (f1 * cos_c)+one;
    vec3 Q1 = f1/f2;
    Q1*=Q1;
    vec3 Q2 = f3/f4;
    Q2*=Q2;
    vec3 F=vec3(0.5)*Q1*(vec3(1.0)+Q2);
    float cos2d = cos_d[0]*cos_d[0];
    float t = r*(1.0-1.0/cos2d);
    float M;

    float rt = r;
    float rb = rt*0.5;
    //0,0,0 = center of object. Could change (have as
    //a uniform).
    vec3 objPos = vec3(0.0, 0.0, 0.0);
    vec3 v = normalize(v_objPos - vec3(0,0,0));
    float c = dot(v,vec3(0.0,0.0,-1.0));
    float s = sqrt(1.0-c);
    vec3 TT = vec3(c, 0.0 ,sign(v_objPos.z)*s);
    vec3 H_ = normalize( H + -dot(N,H)*N );
    float cos_g = dot(T,H_);
    float cos2g = cos_g * cos_g;
    float tt = (rt*rt*cos2g + rb*rb*(1.0-cos2g))*(1.0 - 1.0/cos2d);
    M = (rt * rb * exp(t)) / (4.0*cos2d*cos2d);

    //M = r*exp(t)/(4.0*cos2d*cos2d);

    float A = clamp(2.0*cos_d[0]*min(cos_a[0], cos_b[0])/cos_c[0], 0.0, 1.0);
    specular = vec3(M)*F*vec3(A)/(cos_a*cos_b*vec3(3.14159265358979323));
    specular *= sign(dp);

    //color.rgb = newNormal;
    color = texture(tex,v_texcoord);
    color.rgb *= diffuse;
    color.rgb += specular * texture(stex,v_texcoord).rgb;
    color.rgb += texture(etex,v_texcoord).rgb;

}