/***********************************************/
/*          Copyright (C) 2023 Belmu           */
/*       GNU General Public License V3.0       */
/***********************************************/

#define EDGE_ATTENUATION_FACTOR 0.15

// Kneemund's Edge Attenuation
float kneemundAttenuation(vec2 pos) {
    return 1.0 - quintic(EDGE_ATTENUATION_FACTOR, 0.0, minOf(pos * (1.0 - pos)));
}

vec3 getHitColor(in vec3 hitPosition) {
    #if SSR_REPROJECTION == 1
        hitPosition -= getVelocity(hitPosition);
        return texture(HISTORY_BUFFER, hitPosition.xy).rgb;
    #else
        return texture(DEFERRED_BUFFER, hitPosition.xy).rgb;
    #endif
}

vec3 getSkyFallback(vec2 hitCoords, vec3 reflected, Material material) {
    #if defined WORLD_OVERWORLD
        vec2 coords = projectSphere(mat3(gbufferModelViewInverse) * reflected);
        vec3 sky    = texture(ATMOSPHERE_BUFFER, saturate(coords + randF() * pixelSize)).rgb;

        vec4 clouds = vec4(0.0, 0.0, 0.0, 1.0);
		#if PRIMARY_CLOUDS == 1 || SECONDARY_CLOUDS == 1
            if(saturate(hitCoords) == hitCoords) {
			    clouds = texture(CLOUDS_BUFFER, hitCoords);
            }
		#endif

        return (sky * clouds.a + clouds.rgb) * getSkyLightFalloff(material.lightmap.y);
    #else
        return vec3(0.0);
    #endif
}

//////////////////////////////////////////////////////////
/*------------------ SMOOTH REFLECTIONS ----------------*/
//////////////////////////////////////////////////////////

#if REFLECTIONS_TYPE == 0
    vec3 computeSmoothReflections(vec3 viewPosition, Material material) {
        viewPosition += material.normal * 1e-2;

        vec3 viewDirection = normalize(viewPosition);
        vec3 rayDirection  = reflect(viewDirection, material.normal); 
        vec3 hitPosition   = vec3(0.0);

        float hit     = float(raytrace(depthtex0, viewPosition, rayDirection, SIMPLE_REFLECT_STEPS, randF(), hitPosition));
              hit    *= kneemundAttenuation(hitPosition.xy);
        vec3 hitColor = getHitColor(hitPosition);

        #if defined SKY_FALLBACK
            vec3 color = mix(getSkyFallback(hitPosition.xy, rayDirection, material), hitColor, hit);
        #else
            vec3 color = mix(vec3(0.0), hitColor, hit);
        #endif

        float NdotL   = abs(dot(material.normal, rayDirection));
        float NdotV   = dot(material.normal, -viewDirection);
        float alphaSq = maxEps(material.roughness * material.roughness);

        vec3  F  = fresnelDielectricConductor(NdotL, material.N, material.K);
        float G1 = G1SmithGGX(NdotV, alphaSq);
        float G2 = G2SmithGGX(NdotL, NdotV, alphaSq);

        return NdotV > 0.0 && NdotL > 0.0 ? color * ((F * G2) / G1) : vec3(0.0);
    }
#else

//////////////////////////////////////////////////////////
/*------------------ ROUGH REFLECTIONS -----------------*/
//////////////////////////////////////////////////////////

    vec3 computeRoughReflections(vec3 viewPosition, Material material) {
	    vec3 color = vec3(0.0);
        int samples = 0;

        viewPosition += material.normal * 1e-2;

        vec3  viewDirection = normalize(viewPosition);
        mat3  tbn           = constructViewTBN(material.normal);
        float NdotV         = dot(material.normal, -viewDirection);
	
        for(int i = 0; i < ROUGH_SAMPLES; i++) {
            vec3 microfacet   = tbn * sampleGGXVNDF(-viewDirection * tbn, rand2F(), material.roughness);
		    vec3 rayDirection = reflect(viewDirection, microfacet);	
            float NdotL       = dot(material.normal, rayDirection);

            if(NdotV > 0.0 && NdotL > 0.0) {
                vec3 hitPosition = vec3(0.0);
                
                float hit     = float(raytrace(depthtex0, viewPosition, rayDirection, ROUGH_REFLECT_STEPS, randF(), hitPosition));
                      hit    *= kneemundAttenuation(hitPosition.xy);
                vec3 hitColor = getHitColor(hitPosition);

                #if defined SKY_FALLBACK
                    hitColor = mix(getSkyFallback(hitPosition.xy, rayDirection, material), getHitColor(hitPosition), hit);
                #else
                    hitColor = mix(vec3(0.0), getHitColor(hitPosition), hit);
                #endif

                float MdotV   = dot(microfacet, -viewDirection);
                float alphaSq = maxEps(material.roughness * material.roughness);

                vec3  F  = isEyeInWater == 1 ? vec3(fresnelDielectric(MdotV, 1.333, airIOR)) : fresnelDielectricConductor(MdotV, material.N, material.K);
                float G1 = G1SmithGGX(NdotV, alphaSq);
                float G2 = G2SmithGGX(NdotL, NdotV, alphaSq);

                color += hitColor * ((F * G2) / G1);
                samples++;
            }
	    }
	    return max0(color * rcp(samples));
    }
#endif
