<@include gpu/Config.slh@>
<$VERSION_HEADER$>
//  Generated on <$_SCRIBE_DATE$>
//  lightClusters_drawClusterContent.frag
//
//  Created by Sam Gateau on 9/8/2016.
//  Copyright 2015 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@>


<@include graphics/Light.slh@>
<$declareLightBuffer(256)$>

<@include LightClusterGrid.slh@>

<@include gpu/Color.slh@>
<$declareColorWheel()$>


layout(location=0) in vec2 varTexCoord0;
layout(location=0) out vec4 _fragColor;

void main(void) {

    // Grab the fragment data from the uv
    vec2 texCoord = varTexCoord0.st;

    vec4 fragEyePos = unpackDeferredPositionFromZdb(texCoord);
    vec4 fragWorldPos = getViewInverse() * fragEyePos;
    
    // From frag world pos find the cluster
    vec4 clusterEyePos = frustumGrid_worldToEye(fragWorldPos);
    ivec3 clusterPos = frustumGrid_eyeToClusterPos(clusterEyePos.xyz);
    int clusterIndex = frustumGrid_clusterToIndex(clusterPos);

    ivec3 cluster = clusterGrid_getCluster(clusterIndex);
    int numLights = cluster.x + cluster.y;
    float numLightsScale = clamp(numLights * 0.05, 0.01, 1.0);

    int clusterOffset = cluster.z;

   ivec3 dims = frustumGrid.dims.xyz;
   dims.z +=1;
   ivec3 summedDims = ivec3(dims.x * dims.y, dims.x, 1);
   
   if (clusterPos.x < 0 || clusterPos.x >= dims.x) {
       _fragColor = vec4(0.0);
       return;
   }
   
   if (clusterPos.y < 0 || clusterPos.y >= dims.y) {
       _fragColor = vec4(0.0);
       return;
   }
   if (clusterPos.z < 0 || clusterPos.z > dims.z) {
       _fragColor = vec4(0.0);
       return;
   }
   
       int numLightTouching = 0;
    for (int i = 0; i < numLights; i++) {
        // Need the light now
        int theLightIndex = clusterGrid_getClusterLightId(i, clusterOffset);
        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;

        // Check spot
        if ((i >= cluster.x) && !lightVolume_clipFragToLightVolumeSpotSide(light.volume, fragLightDirLen, cosSpotAngle)) {
            continue;
        }

        numLightTouching++;
    }

    _fragColor = vec4(colorRamp(1.0 - (numLightTouching / 12.0f)), (numLightTouching > 0 ? 0.5 + 0.5 * numLightsScale : 0.0));
}