<!
//  LightCluserGrid.slh
//
//  Created by Sam Gateau on 9/8/16.
//  Copyright 2013 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
!>
<@if not RENDER_LIGHT_CLUSTER_GRID_SLH@>
<@def RENDER_LIGHT_CLUSTER_GRID_SLH@>


struct FrustumGrid {
    float frustumNear;
    float rangeNear;
    float rangeFar;
    float frustumFar;
    ivec3 dims;
    float spare;
    mat4 eyeToGridProj;
    mat4 worldToEyeMat;
    mat4 eyeToWorldMat;
};

uniform frustumGridBuffer {
    FrustumGrid frustumGrid;
};

float projection_getNear(mat4 projection) {
    float planeC = projection[2][3] + projection[2][2];
    float planeD = projection[3][2];
    return planeD / planeC;
}
float projection_getFar(mat4 projection) {
    //float planeA = projection[0][3] - projection[0][2]; All Zeros
    //float planeB = projection[1][3] - projection[1][2]; All Zeros
    float planeC = projection[2][3] - projection[2][2];
    float planeD = /*projection[3][3]*/ -projection[3][2];
    return planeD / planeC;
}

// glsl / C++ compatible source as interface for FrustrumGrid
<@include LightClusterGrid_shared.slh@>

// end of hybrid include


uniform clusterGridBuffer {
    int _clusterGridTable[16384];
};

uniform clusterContentBuffer {
    int _clusterGridContent[16384];
};

ivec3 clusterGrid_getCluster(int index) {
    int clusterDesc = _clusterGridTable[index];
    int numPointLights = 0xFF & (clusterDesc >> 16);
    int numSpotLights = 0xFF & (clusterDesc >> 24);
    int contentOffset = 0xFFFF & (clusterDesc);
    return ivec3(numPointLights, numSpotLights, contentOffset);
}

int clusterGrid_getClusterLightId(int index, ivec2 cluster) {
    int arrayElement = cluster.y + index;
    int element = _clusterGridContent[arrayElement];
    return element;
//    int element = _clusterGridContent[arrayElement >> 1];

//    return (((arrayElement & 0x00000001) == 1) ? (element >> 16) : element) & 0x0000FFFF;
}

<@endif@>