fshader1.glsl

# version 400

in vec3 fN ;
in vec3 fE ;
in vec3 fL ;
in vec2 ftexCoord ;

uniform vec4 ambientProduct ;
uniform vec4 diffuseProduct ;
uniform vec4 specularProduct ;
uniform float shininess ;
uniform sampler2D colorTexture ;

out vec4 frag_color ;

vec4 Phong ( vec3 n )
{
    vec3 N = normalize ( n ) ;
    vec3 E = normalize ( fE ) ;
    vec3 L = normalize ( fL ) ;
    float NdotL = dot (N , L ) ;
    vec3 R = normalize (2.0 * NdotL * N - L ) ;
    float Kd = max ( NdotL , 0.0) ;
    float Ks = ( NdotL < 0.0) ? 0.0 : pow ( max ( dot (R , E ) ,0.0) ,
    shininess ) ;
    vec4 diffuse = Kd * diffuseProduct * texture2D ( colorTexture , ftexCoord ) ;
    vec4 specular = Ks * specularProduct ;
    vec4 ambient = ambientProduct ;
    return ambient + diffuse + specular ;
}

void main ()
{
    if( gl_FrontFacing ) {
        frag_color = vec4 ( Phong ( fN ) . xyz , 1) ;
    }
    else
    {
        frag_color = mix ( vec4 ( Phong ( - fN ) . xyz , 1) , vec4 (0.0 , 0.0 , 0.0 , 1.0) , 0.7) ;
    }
}