//  Generated on <$_SCRIBE_DATE$>
//
//  Created by Olivier Prat on 15/01/18.
//  Copyright 2018 High Fidelity, Inc.
//
//  Distributed under the Apache License, Version 2.0.
//  See the accompanying file LICENSE or http://www.apache.org/licenses/LICENSE-2.0.html
//

// Everything about light
<@include graphics/Light.slh@>
<@include LightingModel.slh@>
<@include LightPoint.slh@>
<@include LightSpot.slh@>
<@include LightClusterGrid.slh@>

<$declareLightBuffer(256)$>
<$declareLightingPoint(supportScattering)$>
<$declareLightingSpot(supportScattering)$>

vec4 evalLocalLighting(ivec3 cluster, int numLights, vec3 fragWorldPos, SurfaceData surface,
                       float fragMetallic, vec3 fragFresnel, vec3 fragAlbedo, float fragScattering,  
                       vec4 midNormalCurvature, vec4 lowNormalCurvature, float opacity) {
    vec4 fragColor = vec4(0.0);
    vec3 fragSpecular = vec3(0.0);
    vec3 fragDiffuse = vec3(0.0);
    int lightClusterOffset = cluster.z;

    // Compute the rougness into gloss2 once:
    bool withScattering = (fragScattering * isScatteringEnabled() > 0.0);

    int numLightTouching = 0;
    for (int i = 0; i < cluster.x; i++) {
        // Need the light now
        int theLightIndex = clusterGrid_getClusterLightId(i, lightClusterOffset);
        Light light = getLight(theLightIndex);

        // Clip againgst the light volume and Make the Light vector going from fragment to light center in world space
        vec4 fragLightVecLen2;
        vec4 fragLightDirLen;

        if (!lightVolume_clipFragToLightVolumePoint(light.volume, fragWorldPos.xyz, fragLightVecLen2)) {
            continue;
        }

        // Allright we re in the light sphere volume
        fragLightDirLen.w = length(fragLightVecLen2.xyz);
        fragLightDirLen.xyz = fragLightVecLen2.xyz / fragLightDirLen.w;
        if (dot(surface.normal, fragLightDirLen.xyz) < 0.0) {
            continue;
        }

        numLightTouching++;

        vec3 diffuse = vec3(1.0);
        vec3 specular = vec3(0.1);

        // Allright we re valid in the volume
        float fragLightDistance = fragLightDirLen.w;
        vec3 fragLightDir = fragLightDirLen.xyz;

        updateSurfaceDataWithLight(surface, fragLightDir);

        // Eval attenuation
        float radialAttenuation = lightIrradiance_evalLightAttenuation(light.irradiance, fragLightDistance);
        vec3 lightEnergy = radialAttenuation * getLightIrradiance(light);

        // Eval shading
        if (withScattering) {
            evalFragShadingScattering(diffuse, specular, fragMetallic, fragFresnel, surface, fragAlbedo,
                                      fragScattering, midNormalCurvature, lowNormalCurvature );
        } else {
           evalFragShadingGloss(diffuse, specular, fragMetallic, fragFresnel, surface, fragAlbedo);
        }

        diffuse *= lightEnergy;
        specular *= lightEnergy;

        fragDiffuse.rgb += diffuse;
        fragSpecular.rgb += specular;
    }

    for (int i = cluster.x; i < numLights; i++) {
        // Need the light now
        int theLightIndex = clusterGrid_getClusterLightId(i, lightClusterOffset);
        Light light = getLight(theLightIndex);

        // Clip againgst the light volume and Make the Light vector going from fragment to light center in world space
        vec4 fragLightVecLen2;
        vec4 fragLightDirLen;
        float cosSpotAngle;

        if (!lightVolume_clipFragToLightVolumePoint(light.volume, fragWorldPos.xyz, fragLightVecLen2)) {
            continue;
        }

        // Allright we re in the light sphere volume
        fragLightDirLen.w = length(fragLightVecLen2.xyz);
        fragLightDirLen.xyz = fragLightVecLen2.xyz / fragLightDirLen.w;
        if (dot(surface.normal, fragLightDirLen.xyz) < 0.0) {
            continue;
        }

        // Check spot
        if (!lightVolume_clipFragToLightVolumeSpotSide(light.volume, fragLightDirLen, cosSpotAngle)) {
            continue;
        }

        numLightTouching++;

        vec3 diffuse = vec3(1.0);
        vec3 specular = vec3(0.1);

        // Allright we re valid in the volume
        float fragLightDistance = fragLightDirLen.w;
        vec3 fragLightDir = fragLightDirLen.xyz;

        updateSurfaceDataWithLight(surface, fragLightDir);

        // Eval attenuation
        float radialAttenuation = lightIrradiance_evalLightAttenuation(light.irradiance, fragLightDistance);
        float angularAttenuation = lightIrradiance_evalLightSpotAttenuation(light.irradiance, cosSpotAngle);
        vec3 lightEnergy = radialAttenuation * angularAttenuation * getLightIrradiance(light);

        // Eval shading
        if (withScattering) {
            evalFragShadingScattering(diffuse, specular, fragMetallic, fragFresnel, surface, fragAlbedo,
                                      fragScattering, midNormalCurvature, lowNormalCurvature );
        } else {
           evalFragShadingGloss(diffuse, specular, fragMetallic, fragFresnel, surface, fragAlbedo);
        }

        diffuse *= lightEnergy;
        specular *= lightEnergy;

        fragDiffuse.rgb += diffuse;
        fragSpecular.rgb += specular;
    }

    fragDiffuse *= isDiffuseEnabled();
    fragSpecular *= isSpecularEnabled();

    fragColor.rgb += fragDiffuse;
    fragColor.rgb += evalSpecularWithOpacity(fragSpecular, opacity);
    return fragColor;
}