#version 120

 

uniform sampler2D Texture;

uniform sampler2D NormalMap;

uniform float TexNormalScale;

 

varying vec3 Normal;

varying vec3 PixPos;

 

vec3 Mul(vec2 Vec, mat2x3 M)

{

    return vec3(Vec[0][0] * Vec.x + Vec[1][0] * Vec.y,

                Vec[0][1] * Vec.x + Vec[1][1] * Vec.y,

                Vec[0][2] * Vec.x + Vec[1][2] * Vec.y);

}

mat3 ComputeTBN(vec3 Normal, vec3 Position, vec2 TexCoords)

{

    vec3 EdgeFaceA = dFdx(Position);

    vec3 EdgeFaceB = dFdy(Position);

    vec2 UvEdgeA = dFdx(TexCoords);

    vec2 UvEdgeB = dFdy(TexCoords);

 

    mat2x3 M = mat2x3(EdgeFaceA, EdgeFaceB);

    vec3 Tangent = Mul(vec2(UvEdgeA.x, UvEdgeB.x), M);

    vec3 Bitangent = Mul(vec2(UvEdgeA.y, UvEdgeB.y), M);

 

    float MaxL = max(length(Tangent), length(Bitangent));

    return mat3(Tangent / MaxL, Bitangent / MaxL, Normal);

}

 

void main()

{

    vec3 Shaded = vec3(gl_FrontMaterial.emission);

    vec3 EyeVector = normalize(-PixPos);

    vec3 Normal = normalize(Normal);

    mat3 TBN = ComputeTBN(Normal, PixPos, gl_TexCoord[0].st);

   

    Normal = TBN * vec3(texture2D(NormalMap, gl_TexCoord[0].st) - 0.5f);

 

    int i;

    for(i = 0; i < 2; i++)

    {

        vec3 LightDirection = normalize(vec3(gl_LightSource[i].position) - PixPos);

        vec3 ReflectVector = normalize(reflect(-LightDirection, Normal));

 

        //Ambient

        Shaded += vec3(gl_LightSource[i].ambient) * vec3(gl_FrontMaterial.ambient);

        //Diffuse

        Shaded += vec3(gl_LightSource[i].diffuse) * vec3(gl_FrontMaterial.diffuse) * max(dot(Normal, LightDirection), 0.0);

        //Specular

        Shaded += vec3(gl_LightSource[i].specular) * vec3(gl_FrontMaterial.specular) * pow(max(dot(ReflectVector, EyeVector), 0.0), gl_FrontMaterial.shininess);

    }

    gl_FragColor = vec4(Shaded, 1.0) * gl_Color * texture2D(Texture, gl_TexCoord[0].st);

}