uniform vec2 fg_BufferSize;
uniform vec3 fg_Planes;

uniform sampler2D depth_tex;
uniform sampler2D normal_tex;
uniform sampler2D color_tex;
uniform sampler2D spec_emis_tex;
uniform vec4 LightPosition;
uniform vec4 Ambient;
uniform vec4 Diffuse;
uniform vec4 Specular;
uniform vec3 Attenuation;
uniform float Near;
uniform float Far;

varying vec4 ecPosition;

vec3 position( vec3 viewDir, vec2 coords, sampler2D depth_tex );
vec3 normal_decode(vec2 enc);

void main() {
    vec3 ray = ecPosition.xyz / ecPosition.w;
    vec3 ecPos3 = ray;
    vec3 viewDir = normalize(ray);
    vec2 coords = gl_FragCoord.xy / fg_BufferSize;

    vec3 normal = normal_decode(texture2D( normal_tex, coords ).rg);
    vec4 spec_emis = texture2D( spec_emis_tex, coords );

    vec3 pos = position(viewDir, coords, depth_tex);

    if ( pos.z < ecPos3.z ) // Negative direction in z
        discard; // Don't light surface outside the light volume

    vec3 VP = LightPosition.xyz - pos;
    if ( dot( VP, VP ) > ( Far * Far ) )
        discard; // Don't light surface outside the light volume

    float d = length( VP );
    VP /= d;

    vec3 halfVector = normalize(VP - viewDir);

    float att = 1.0 / (Attenuation.x + Attenuation.y * d + Attenuation.z *d*d);

    float cosAngIncidence = clamp(dot(normal, VP), 0.0, 1.0);

    float nDotVP = max(0.0, dot(normal, VP));
    float nDotHV = max(0.0, dot(normal, halfVector));

    vec4 color = texture2D( color_tex, coords );
    vec4 Iamb = Ambient * color * att;
    vec4 Idiff = Diffuse * color * att * nDotVP;

    vec3 Ispec = vec3(0.0);
    if (cosAngIncidence > 0.0)
        Ispec = pow( nDotHV, spec_emis.y * 128.0 ) * spec_emis.x * att * Specular.rgb;

    gl_FragColor = vec4(Iamb.rgb + Idiff.rgb + Ispec, 1.0);
}