<@include gpu/Config.slh@>
<$VERSION_HEADER$>
//  Generated on <$_SCRIBE_DATE$>
//
//  local_lights_shading.frag
//  fragment shader
//
//  Created by Sam Gateau on 9/6/2016.
//  Copyright 2014 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 deferred buffer
<@include DeferredBufferRead.slh@>

<$declareDeferredCurvature()$>

// Everything about light
<@include model/Light.slh@>
<$declareLightBuffer(256)$>
<@include LightingModel.slh@>


<@include LightPoint.slh@>
<$declareLightingPoint(supportScattering)$>
<@include LightSpot.slh@>
<$declareLightingSpot(supportScattering)$>

<@include LightClusterGrid.slh@>

in vec2 _texCoord0;
out vec4 _fragColor;

void main(void) {
    // Grab the fragment data from the uv
    vec2 texCoord = _texCoord0.st;

    DeferredFrameTransform deferredTransform = getDeferredFrameTransform();
    DeferredFragment frag = unpackDeferredFragment(deferredTransform, texCoord);
    vec4 fragPosition = frag.position;

    if (frag.mode == FRAG_MODE_UNLIT) {
        discard;
    }

    // Frag pos in world
    mat4 invViewMat = getViewInverse();
    vec4 fragPos = invViewMat * fragPosition;

    // From frag world pos find the cluster
    vec4 clusterEyePos = frustumGrid_worldToEye(fragPos);
    ivec3 clusterPos = frustumGrid_eyeToClusterPos(clusterEyePos.xyz);

    ivec3 cluster = clusterGrid_getCluster(frustumGrid_clusterToIndex(clusterPos));
    int numLights = cluster.x + cluster.y;
    if (numLights <= 0) {
        discard;
    }
    int lightClusterOffset = cluster.z;

    ivec3 dims = frustumGrid.dims.xyz;
    if (clusterPos.x < 0 || clusterPos.x >= dims.x) {
        discard;
    }

    if (clusterPos.y < 0 || clusterPos.y >= dims.y) {
        discard;
    }
    if (clusterPos.z < 0 || clusterPos.z > dims.z) {
        discard;
    }

    vec4 midNormalCurvature;
    vec4 lowNormalCurvature;
    if (frag.mode == FRAG_MODE_SCATTERING) {
        unpackMidLowNormalCurvature(texCoord, midNormalCurvature, lowNormalCurvature);
    }


    // Frag to eye vec
    vec4 fragEyeVector = invViewMat * vec4(-frag.position.xyz, 0.0);
    vec3 fragEyeDir = normalize(fragEyeVector.xyz);

    // Compute the rougness into gloss2 once:
    float fragGloss2 = pow(frag.roughness + 0.001, 4.0);
    bool withScattering = (frag.scattering * 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, fragPos.xyz, fragLightVecLen2)) {
            continue;
        }

        // Allright we re in the light sphere volume
        fragLightDirLen.w = length(fragLightVecLen2.xyz);
        fragLightDirLen.xyz = fragLightVecLen2.xyz / fragLightDirLen.w;
        if (dot(frag.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;

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

        // Eval shading
        if (withScattering) {
            evalFragShadingScattering(diffuse, specular, frag.normal, fragLightDir, fragEyeDir, frag.metallic, frag.fresnel, frag.roughness, frag.albedo
                ,frag.scattering, midNormalCurvature, lowNormalCurvature );
        } else {
           evalFragShadingGloss(diffuse, specular, frag.normal, fragLightDir, fragEyeDir, frag.metallic, frag.fresnel, fragGloss2, frag.albedo);
        }

        diffuse *= lightEnergy * isDiffuseEnabled();
        specular *= lightEnergy * isSpecularEnabled();

        _fragColor.rgb += diffuse;
        _fragColor.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, fragPos.xyz, fragLightVecLen2)) {
            continue;
        }

        // Allright we re in the light sphere volume
        fragLightDirLen.w = length(fragLightVecLen2.xyz);
        fragLightDirLen.xyz = fragLightVecLen2.xyz / fragLightDirLen.w;
        if (dot(frag.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;

        // 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, frag.normal, fragLightDir, fragEyeDir, frag.metallic, frag.fresnel, frag.roughness, frag.albedo
                ,frag.scattering, midNormalCurvature, lowNormalCurvature );
        } else {
           evalFragShadingGloss(diffuse, specular, frag.normal, fragLightDir, fragEyeDir, frag.metallic, frag.fresnel, fragGloss2, frag.albedo);
        }

        diffuse *= lightEnergy * isDiffuseEnabled();
        specular *= lightEnergy * isSpecularEnabled();

        _fragColor.rgb += diffuse;
        _fragColor.rgb += specular;
    }

}