Debugging the grid content

libraries/gpu/src/gpu/Buffer.h

@@ -391,11 +391,14 @@ public:
         ~StructBuffer<T>() {};
         StructBuffer<T>() : gpu::BufferView(makeBuffer()) {}
 
-        const T* operator ->() const { return &get<T>(); }
+
         T& edit() {
             return BufferView::edit<T>(0);
         }
-
+        const T& get() const {
+            return BufferView::get<T>(0);
+        }
+        const T* operator ->() const { return &get(); }
     };
 };
 

libraries/gpu/src/gpu/Format.cpp

@@ -18,6 +18,7 @@ const Element Element::VEC2F_UV{ VEC2, FLOAT, UV };
 const Element Element::VEC2F_XY{ VEC2, FLOAT, XY };
 const Element Element::VEC3F_XYZ{ VEC3, FLOAT, XYZ };
 const Element Element::VEC4F_XYZW{ VEC4, FLOAT, XYZW };
-const Element Element::INDEX_UINT16{ SCALAR, UINT16, INDEX };
+const Element Element::INDEX_UINT16 { SCALAR, UINT16, INDEX };
+const Element Element::INDEX_INT32 { SCALAR, INT32, INDEX };
 const Element Element::PART_DRAWCALL{ VEC4, UINT32, PART };
 

libraries/gpu/src/gpu/Format.h

@@ -236,6 +236,7 @@ public:
     static const Element VEC3F_XYZ;
     static const Element VEC4F_XYZW;
     static const Element INDEX_UINT16;
+    static const Element INDEX_INT32;
     static const Element PART_DRAWCALL;
     
  protected:

libraries/render-utils/src/LightClusterGrid.slh

@@ -46,4 +46,13 @@ float projection_getFar(mat4 projection) {
 
 // end of hybrid include
 
+
+uniform clusterGridBuffer {
+    int _clusterGridTable[10000];
+};
+
+uniform clusterContentBuffer {
+    int _clusterGridContent[10000];
+};
+
 <@endif@>

libraries/render-utils/src/LightClusterGrid_shared.slh

@@ -17,11 +17,16 @@ vec3 frustumGrid_gridToVolume(vec3 pos, ivec3 dims) {
 }
 
 
+float frustumGrid_volumeToGridDepth(float vposZ, ivec3 dims) {
+    return frustumGrid_depthRampInverse(vposZ) * float(dims.z);
+}
+
 vec3 frustumGrid_volumeToGrid(vec3 vpos, ivec3 dims) {
     vec3 gridPos = vec3(vpos.x, vpos.y, frustumGrid_depthRampInverse(vpos.z)) * vec3(dims);
     return gridPos;
 }
 
+
 vec4 frustumGrid_volumeToClip(vec3 vpos, float rangeNear, float rangeFar) {
     vec3 ndcPos = vec3(-1.0 + 2.0 * vpos.x, -1.0 + 2.0 * vpos.y, vpos.z);
     float depth = rangeNear * (1 - ndcPos.z) + rangeFar * (ndcPos.z);
@@ -42,6 +47,10 @@ vec3 frustumGrid_volumeToEye(vec3 vpos, mat4 projection, float rangeNear, float
     return frustumGrid_clipToEye(frustumGrid_volumeToClip(vpos, rangeNear, rangeFar), projection);
 }
 
+float frustumGrid_eyeToVolumeDepth(float eposZ, float rangeNear, float rangeFar) {
+    return (-eposZ - rangeNear) / (rangeFar - rangeNear);
+}
+
 
 vec3 frustumGrid_eyeToVolume(vec3 epos, mat4 projection, float rangeNear, float rangeFar) {
     vec4 clipPos = vec4(epos.x * projection[0][0] + epos.z * projection[2][0],
@@ -57,7 +66,7 @@ vec3 frustumGrid_eyeToVolume(vec3 epos, mat4 projection, float rangeNear, float
 
 
 int frustumGrid_numClusters() {
-    return frustumGrid.dims.x * frustumGrid.dims.y * (frustumGrid.dims.z);
+    return frustumGrid.dims.x * frustumGrid.dims.y * (frustumGrid.dims.z + 1);
 }
 
 vec3 frustumGrid_clusterPosToEye(ivec3 clusterPos, vec3 offset) {
@@ -73,6 +82,27 @@ vec3 frustumGrid_clusterPosToEye(ivec3 clusterPos, vec3 offset) {
 }
 
 
+int frustumGrid_eyeDepthToClusterLayer(float eyeZ) {
+    if ((eyeZ > -frustumGrid.frustumNear) || (eyeZ < -frustumGrid.frustumFar)) {
+        return -1;
+    }
+
+    if (eyeZ > -frustumGrid.rangeNear) {
+        return -1;
+    }
+
+    float volumeZ = frustumGrid_eyeToVolumeDepth(eyeZ, frustumGrid.rangeNear, frustumGrid.rangeFar);
+
+    float gridZ = frustumGrid_volumeToGridDepth(volumeZ, frustumGrid.dims);
+
+    if (gridZ >= frustumGrid.dims.z) {
+        gridZ = frustumGrid.dims.z;
+    }
+
+
+    return int(gridZ);
+}
+
 ivec3 frustumGrid_eyeToClusterPos(vec3 eyePos) {
     if ((eyePos.z > -frustumGrid.frustumNear) || (eyePos.z < -frustumGrid.frustumFar)) {
         return ivec3(-1);

libraries/render-utils/src/LightClusters.cpp

@@ -21,6 +21,10 @@
 //#include "lightClusters_drawClusterFromDepth_vert.h"
 #include "lightClusters_drawClusterFromDepth_frag.h"
 
+
+#include "lightClusters_drawClusterContent_vert.h"
+#include "lightClusters_drawClusterContent_frag.h"
+
 enum LightClusterGridShader_MapSlot {
     DEFERRED_BUFFER_LINEAR_DEPTH_UNIT = 0,
 };
@@ -31,14 +35,32 @@ enum LightClusterGridShader_BufferSlot {
     CAMERA_CORRECTION_BUFFER_SLOT,
     LIGHT_GPU_SLOT = render::ShapePipeline::Slot::LIGHT,
     LIGHT_INDEX_GPU_SLOT,
+
+    LIGHT_CLUSTER_GRID_CLUSTER_GRID_SLOT,
+    LIGHT_CLUSTER_GRID_CLUSTER_CONTENT_SLOT,
 };
 
 #include "DeferredLightingEffect.h"
 
 LightClusters::LightClusters() :
-_lightIndicesBuffer(std::make_shared<gpu::Buffer>()) {
+    _lightIndicesBuffer(std::make_shared<gpu::Buffer>()),
+    _clusterGridBuffer(std::make_shared<gpu::Buffer>(), gpu::Element::INDEX_INT32),
+    _clusterContentBuffer(std::make_shared<gpu::Buffer>(), gpu::Element::INDEX_INT32) {
+    setDimensions(_frustumGridBuffer->dims, 10000);
 }
 
+void LightClusters::setDimensions(glm::uvec3 gridDims, uint32_t listBudget) {
+    _frustumGridBuffer.edit().dims = gridDims;
+
+    _numClusters = _frustumGridBuffer.edit().frustumGrid_numClusters();
+
+    _clusterGridBuffer._size = _clusterGridBuffer._buffer->resize(_numClusters * sizeof(uint32_t));
+    _clusterContentBuffer._size = _clusterContentBuffer._buffer->resize(listBudget * sizeof(uint32_t));
+    _clusterGrid.resize(_numClusters, EMPTY_CLUSTER);
+    _clusterContent.resize(listBudget, INVALID_LIGHT);
+}
+
+
 void LightClusters::updateFrustum(const ViewFrustum& frustum) {
     _frustum = frustum;
 
@@ -51,23 +73,23 @@ void LightClusters::updateLightStage(const LightStagePointer& lightStage) {
   }
 
 void LightClusters::updateLightFrame(const LightStage::Frame& lightFrame, bool points, bool spots) {
-    
+
     // start fresh
     _visibleLightIndices.clear();
-    
+
     // Now gather the lights
     // gather lights
     auto& srcPointLights = lightFrame._pointLights;
     auto& srcSpotLights = lightFrame._spotLights;
-    int numPointLights = (int) srcPointLights.size();
-   // int offsetPointLights = 0;
-    int numSpotLights = (int) srcSpotLights.size();
-   // int offsetSpotLights = numPointLights;
-    
+    int numPointLights = (int)srcPointLights.size();
+    // int offsetPointLights = 0;
+    int numSpotLights = (int)srcSpotLights.size();
+    // int offsetSpotLights = numPointLights;
+
     _visibleLightIndices.resize(numPointLights + numSpotLights + 1);
-    
+
     _visibleLightIndices[0] = 0;
-    
+
     if (points && !srcPointLights.empty()) {
         memcpy(_visibleLightIndices.data() + (_visibleLightIndices[0] + 1), srcPointLights.data(), srcPointLights.size() * sizeof(int));
         _visibleLightIndices[0] += (int)srcPointLights.size();
@@ -76,11 +98,144 @@ void LightClusters::updateLightFrame(const LightStage::Frame& lightFrame, bool p
         memcpy(_visibleLightIndices.data() + (_visibleLightIndices[0] + 1), srcSpotLights.data(), srcSpotLights.size() * sizeof(int));
         _visibleLightIndices[0] += (int)srcSpotLights.size();
     }
-  
+
     _lightIndicesBuffer._buffer->setData(_visibleLightIndices.size() * sizeof(int), (const gpu::Byte*) _visibleLightIndices.data());
     _lightIndicesBuffer._size = _visibleLightIndices.size() * sizeof(int);
 }
 
+void LightClusters::updateClusters() {
+    // Clean up last info
+    std::vector< std::vector< uint32_t > > clusterGrid(_numClusters);
+
+    _clusterGrid.resize(_numClusters, EMPTY_CLUSTER);
+    uint32_t maxNumIndices = _clusterContent.size();
+    _clusterContent.resize(maxNumIndices, INVALID_LIGHT);
+
+    auto theFrustumGrid(_frustumGridBuffer.get());
+
+    glm::ivec3 gridPosToOffset(1, theFrustumGrid.dims.x, theFrustumGrid.dims.x * theFrustumGrid.dims.y);
+
+    uint32_t numClusterTouched = 0;
+    for (size_t lightNum = 1; lightNum < _visibleLightIndices.size(); ++lightNum) {
+        auto lightId = _visibleLightIndices[lightNum];
+        auto light = _lightStage->getLight(lightId);
+        if (!light)
+            continue;
+
+        auto worldOri = light->getPosition();
+        auto radius = light->getMaximumRadius();
+
+        // Bring into frustum eye space
+        auto eyeOri = theFrustumGrid.frustumGrid_worldToEye(glm::vec4(worldOri, 1.0f));
+
+        // Remove light that slipped through and is not in the z range
+        float eyeZMax = eyeOri.z - radius;
+        if (eyeZMax > -theFrustumGrid.rangeNear) {
+            continue;
+        }
+        float eyeZMin = eyeOri.z + radius;
+        if (eyeZMin < -theFrustumGrid.rangeFar) {
+            continue;
+        }
+
+        // Get z slices
+        int zMin = theFrustumGrid.frustumGrid_eyeDepthToClusterLayer(eyeZMin);
+        int zMax = theFrustumGrid.frustumGrid_eyeDepthToClusterLayer(eyeZMax);
+        // That should never happen
+        if (zMin == -1 && zMax == -1) {
+            continue;
+        }
+
+
+        // 
+        float eyeOriLen2 = glm::length2(eyeOri);
+
+        // CLamp the z range 
+        zMin = std::max(0, zMin);
+
+
+
+        // find 2D corners of the sphere in grid
+        int xMin { 0 };
+        int xMax { theFrustumGrid.dims.x - 1 };
+        int yMin { 0 };
+        int yMax { theFrustumGrid.dims.y - 1 };
+
+        float radius2 = radius * radius;
+        auto eyeOriH = eyeOri;
+        auto eyeOriV = eyeOri;
+
+        eyeOriH.y = 0.0f;
+        eyeOriV.x = 0.0f;
+
+        float eyeOriLen2H = glm::length2(eyeOriH);
+        float eyeOriLen2V = glm::length2(eyeOriV);
+
+        if ((eyeOriLen2H > radius2) && (eyeOriLen2V > radius2)) {
+            float eyeOriLenH = sqrt(eyeOriLen2H);
+            float eyeOriLenV = sqrt(eyeOriLen2V);
+
+            auto eyeOriDirH = glm::vec3(eyeOriH) / eyeOriLenH;
+            auto eyeOriDirV = glm::vec3(eyeOriV) / eyeOriLenV;
+
+
+
+            float eyeToTangentCircleLenH = sqrt(eyeOriLen2H - radius2);
+            float eyeToTangentCircleLenV = sqrt(eyeOriLen2V - radius2);
+
+            float eyeToTangentCircleTanH = radius / eyeToTangentCircleLenH;
+            float eyeToTangentCircleTanV = radius / eyeToTangentCircleLenV;
+
+            float eyeToTangentCircleCosH = eyeToTangentCircleLenH / eyeOriLenH;
+            float eyeToTangentCircleCosV = eyeToTangentCircleLenV / eyeOriLenV;
+
+            float eyeToTangentCircleSinH = radius / eyeOriLenH;
+            float eyeToTangentCircleSinV = radius / eyeOriLenV;
+
+
+            // rotate the eyeToOriDir (H & V) in both directions
+            glm::vec3 leftDir(eyeOriDirH.x * eyeToTangentCircleCosH - eyeOriDirH.z * eyeToTangentCircleSinH, 0.0f, eyeOriDirH.x * eyeToTangentCircleSinH + eyeOriDirH.z * eyeToTangentCircleCosH);
+            glm::vec3 rightDir(eyeOriDirH.x * eyeToTangentCircleCosH + eyeOriDirH.z * eyeToTangentCircleSinH, 0.0f, eyeOriDirH.x * -eyeToTangentCircleSinH + eyeOriDirH.z * eyeToTangentCircleCosH);
+            glm::vec3 bottomDir(0.0f, eyeOriDirV.y * eyeToTangentCircleCosV - eyeOriDirV.z * eyeToTangentCircleSinV, eyeOriDirV.y * eyeToTangentCircleSinV + eyeOriDirV.z * eyeToTangentCircleCosV);
+            glm::vec3 topDir(0.0f, eyeOriDirV.y * eyeToTangentCircleCosV + eyeOriDirV.z * eyeToTangentCircleSinV, eyeOriDirV.y * -eyeToTangentCircleSinV + eyeOriDirV.z * eyeToTangentCircleCosV);
+
+        }
+
+        // now voxelize
+        for (auto z = zMin; z <= zMax; z++) {
+            for (auto y = yMin; y <= yMax; y++) {
+                for (auto x = xMin; x <= xMax; x++) {
+                    auto index = x + gridPosToOffset.y * y + gridPosToOffset.z * z;
+                    clusterGrid[index].emplace_back(lightId);
+                    numClusterTouched++;
+                }
+            }
+        }
+    }
+
+    // Lights have been gathered now reexpress in terms of 2 sequential buffers
+
+    uint16_t indexOffset = 0;
+    for (int i = 0; i < clusterGrid.size(); i++) {
+        auto& cluster = clusterGrid[i];
+        uint16_t numLights = ((uint16_t)cluster.size());
+        uint16_t offset = indexOffset;
+
+        _clusterGrid[i] = (uint32_t)((numLights << 16) | offset);
+
+        if (numLights) {
+            memcpy(_clusterContent.data() + indexOffset, cluster.data(), numLights * sizeof(uint32_t));
+        }
+
+        indexOffset += numLights;
+    }
+
+    // update the buffers
+    _clusterGridBuffer._buffer->setData(_clusterGridBuffer._size, (gpu::Byte*) _clusterGrid.data());
+    _clusterContentBuffer._buffer->setSubData(0, indexOffset * sizeof(uint32_t), (gpu::Byte*) _clusterContent.data());
+}
+
+
 
 LightClusteringPass::LightClusteringPass() {
 }
@@ -122,6 +277,8 @@ void LightClusteringPass::run(const render::SceneContextPointer& sceneContext, c
     _lightClusters->updateLightStage(lightStage);
     _lightClusters->updateLightFrame(lightStage->_currentFrame, lightingModel->isPointLightEnabled(), lightingModel->isSpotLightEnabled());
     
+    _lightClusters->updateClusters();
+
     output = _lightClusters;
 }
 
@@ -190,6 +347,35 @@ const gpu::PipelinePointer DebugLightClusters::getDrawClusterFromDepthPipeline()
     return _drawClusterFromDepth;
 }
 
+const gpu::PipelinePointer DebugLightClusters::getDrawClusterContentPipeline() {
+    if (!_drawClusterContent) {
+        auto vs = gpu::Shader::createVertex(std::string(lightClusters_drawClusterContent_vert));
+        auto ps = gpu::Shader::createPixel(std::string(lightClusters_drawClusterContent_frag));
+        gpu::ShaderPointer program = gpu::Shader::createProgram(vs, ps);
+
+        gpu::Shader::BindingSet slotBindings;
+        slotBindings.insert(gpu::Shader::Binding(std::string("frustumGridBuffer"), LIGHT_CLUSTER_GRID_FRUSTUM_GRID_SLOT));
+        slotBindings.insert(gpu::Shader::Binding(std::string("clusterGridBuffer"), LIGHT_CLUSTER_GRID_CLUSTER_GRID_SLOT));
+        slotBindings.insert(gpu::Shader::Binding(std::string("clusterContentBuffer"), LIGHT_CLUSTER_GRID_CLUSTER_CONTENT_SLOT));
+
+
+        gpu::Shader::makeProgram(*program, slotBindings);
+
+
+        auto state = std::make_shared<gpu::State>();
+
+        state->setDepthTest(true, false, gpu::LESS_EQUAL);
+
+        // Blend on transparent
+        state->setBlendFunction(true, gpu::State::SRC_ALPHA, gpu::State::BLEND_OP_ADD, gpu::State::INV_SRC_ALPHA);
+
+        // Good to go add the brand new pipeline
+        _drawClusterContent = gpu::Pipeline::create(program, state);
+    }
+    return _drawClusterContent;
+}
+
+
 void DebugLightClusters::run(const render::SceneContextPointer& sceneContext, const render::RenderContextPointer& renderContext, const Inputs& inputs) {
     auto deferredTransform = inputs.get0();
     auto deferredFramebuffer = inputs.get1();
@@ -232,6 +418,17 @@ void DebugLightClusters::run(const render::SceneContextPointer& sceneContext, co
         batch.setResourceTexture(DEFERRED_BUFFER_LINEAR_DEPTH_UNIT, nullptr);
         batch.setUniformBuffer(DEFERRED_FRAME_TRANSFORM_BUFFER_SLOT, nullptr);
     }
+
+    if (doDrawContent) {
+        // bind the one gpu::Pipeline we need
+        batch.setPipeline(getDrawClusterContentPipeline());
+        batch.setUniformBuffer(LIGHT_CLUSTER_GRID_CLUSTER_GRID_SLOT, lightClusters->_clusterGridBuffer);
+        batch.setUniformBuffer(LIGHT_CLUSTER_GRID_CLUSTER_CONTENT_SLOT, lightClusters->_clusterContentBuffer);
+
+        auto dims = lightClusters->_frustumGridBuffer->dims;
+        glm::ivec3 summedDims(dims.x*dims.y * dims.z, dims.x*dims.y, dims.x);
+        batch.drawInstanced(summedDims.x, gpu::LINES, 24, 0);
+    }
     
     if (doDrawGrid) {
         // bind the one gpu::Pipeline we need

libraries/render-utils/src/LightClusters.h

@@ -57,12 +57,16 @@ public:
     
     LightClusters();
 
+    void setDimensions(glm::uvec3 gridDims, uint32_t listBudget);
+
     void updateFrustum(const ViewFrustum& frustum);
 
     void updateLightStage(const LightStagePointer& lightStage);
 
     void updateLightFrame(const LightStage::Frame& lightFrame, bool points = true, bool spots = true);
-    
+
+    void updateClusters();
+
     ViewFrustum _frustum;
 
     LightStagePointer _lightStage;
@@ -72,8 +76,17 @@ public:
     gpu::StructBuffer<FrustumGrid> _frustumGridBuffer;
 
     LightStage::LightIndices _visibleLightIndices;
-    
     gpu::BufferView _lightIndicesBuffer;
+
+    uint32_t _numClusters { 0 };
+
+    const uint32_t EMPTY_CLUSTER { 0x0000FFFF };
+    const uint32_t INVALID_LIGHT { 0xFFFFFFFF };
+
+    std::vector<uint32_t> _clusterGrid;
+    std::vector<uint32_t> _clusterContent;
+    gpu::BufferView _clusterGridBuffer;
+    gpu::BufferView _clusterContentBuffer;
 };
 
 using LightClustersPointer = std::shared_ptr<LightClusters>;
@@ -162,10 +175,13 @@ protected:
     gpu::BufferPointer _gridBuffer;
     gpu::PipelinePointer _drawClusterGrid;
     gpu::PipelinePointer _drawClusterFromDepth;
+    gpu::PipelinePointer _drawClusterContent;
     const gpu::PipelinePointer getDrawClusterGridPipeline();
     const gpu::PipelinePointer getDrawClusterFromDepthPipeline();
+    const gpu::PipelinePointer getDrawClusterContentPipeline();
     bool doDrawGrid{ false };
-    bool doDrawClusterFromDepth{ false };
+    bool doDrawClusterFromDepth { false };
+    bool doDrawContent { true };
 };
 
 #endif

libraries/render-utils/src/LightPayload.cpp

@@ -55,6 +55,7 @@ void LightPayload::render(RenderArgs* args) {
     // Do we need to allocate the light in the stage ?
     if (LightStage::isIndexInvalid(_index)) {
         _index = _stage->addLight(_light);
+        _needUpdate = false;
     }
     // Need an update ?
     if (_needUpdate) {

libraries/render-utils/src/LightStage.cpp

@@ -146,8 +146,12 @@ void LightStage::updateLightArrayBuffer(Index lightId) {
     }
 
     // lightArray is big enough so we can remap
-    auto& light = _lights._elements[lightId];
-    auto lightSchema = light->getSchemaBuffer().get<model::Light::Schema>();
-    _lightArrayBuffer->setSubData<model::Light::Schema>(lightId, lightSchema);
+    auto light = _lights._elements[lightId];
+    if (light) {
+        auto lightSchema = light->getSchemaBuffer().get<model::Light::Schema>();
+        _lightArrayBuffer->setSubData<model::Light::Schema>(lightId, lightSchema);
+    } else {
+        // this should not happen ?
+    }
 }
 

libraries/render-utils/src/RenderDeferredTask.cpp

@@ -192,7 +192,9 @@ RenderDeferredTask::RenderDeferredTask(CullFunctor cullFunctor) {
         const auto debugFramebuffers = render::Varying(DebugDeferredBuffer::Inputs(deferredFramebuffer, linearDepthTarget, surfaceGeometryFramebuffer, ambientOcclusionFramebuffer));
         addJob<DebugDeferredBuffer>("DebugDeferredBuffer", debugFramebuffers);
 
-        addJob<DebugSubsurfaceScattering>("DebugScattering", deferredLightingInputs);
+        const auto debugSubsurfaceScatteringInputs = DebugSubsurfaceScattering::Inputs(deferredFrameTransform, deferredFramebuffer, lightingModel,
+            surfaceGeometryFramebuffer, ambientOcclusionFramebuffer, scatteringResource).hasVarying();
+        addJob<DebugSubsurfaceScattering>("DebugScattering", debugSubsurfaceScatteringInputs);
 
         const auto debugAmbientOcclusionInputs = DebugAmbientOcclusion::Inputs(deferredFrameTransform, deferredFramebuffer, linearDepthTarget, ambientOcclusionUniforms).hasVarying();
         addJob<DebugAmbientOcclusion>("DebugAmbientOcclusion", debugAmbientOcclusionInputs);

libraries/render-utils/src/lightClusters_drawClusterContent.slf

@@ -0,0 +1,19 @@
+<@include gpu/Config.slh@>
+<$VERSION_HEADER$>
+//  Generated on <$_SCRIBE_DATE$>
+//  lightClusters_drawClusterContent.slf
+//
+//  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
+//
+
+in vec4 varColor;
+out vec4 outFragColor;
+
+
+void main(void) {
+    outFragColor = varColor;
+}

libraries/render-utils/src/lightClusters_drawClusterContent.slv

@@ -0,0 +1,74 @@
+<@include gpu/Config.slh@>
+<$VERSION_HEADER$>
+//  Generated on <$_SCRIBE_DATE$>
+//
+//  lightClusters_drawClusterContent.slv
+//  Vertex shader
+//
+//  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
+//
+
+<@include gpu/Transform.slh@>
+<$declareStandardTransform()$>
+
+<@include LightClusterGrid.slh@>
+
+<@include gpu/Color.slh@>
+<$declareColorWheel()$>
+
+
+
+
+out vec4 varColor;
+
+
+void main(void) {
+    const vec4 UNIT_BOX[8] = vec4[8](
+        vec4(0.0, 0.0, 0.0, 1.0),
+        vec4(1.0, 0.0, 0.0, 1.0),
+        vec4(0.0, 1.0, 0.0, 1.0),
+        vec4(1.0, 1.0, 0.0, 1.0),
+        vec4(0.0, 0.0, 1.0, 1.0),
+        vec4(1.0, 0.0, 1.0, 1.0),
+        vec4(0.0, 1.0, 1.0, 1.0),
+        vec4(1.0, 1.0, 1.0, 1.0)
+    );
+    const int UNIT_BOX_LINE_INDICES[24] = int[24](
+        0, 1,
+        1, 3,
+        3, 2,
+        2, 0,
+        4, 5,
+        5, 7,
+        7, 6,
+        6, 4,
+        2, 6,
+        3, 7,
+        0, 4,
+        1, 5
+    );
+    vec4 pos = UNIT_BOX[UNIT_BOX_LINE_INDICES[gl_VertexID]];
+
+    ivec3 dims = frustumGrid.dims.xyz;
+
+    ivec3 summedDims = ivec3(dims.x * dims.y, dims.x, 1);
+
+    int layer = gl_InstanceID / summedDims.x;
+    int offsetInLayer = gl_InstanceID % summedDims.x;
+    ivec3 clusterPos = ivec3(offsetInLayer % summedDims.y, offsetInLayer / summedDims.y, layer);
+
+
+    vec3 eyePos = frustumGrid_clusterPosToEye(clusterPos, vec3(0.05) + 0.9 * pos.xyz);
+    vec4 worldPos = frustumGrid_eyeToWorld(vec4(eyePos.xyz, 1.0));
+
+
+    // standard transform
+    TransformCamera cam = getTransformCamera();
+    <$transformWorldToClipPos(cam, worldPos, gl_Position)$>
+
+        varColor = vec4(colorWheel(fract(float(gl_InstanceID) / float(frustumGrid_numClusters()))), 0.9);
+}