BansheeEngine/Source/RenderBeast/Include/BsLightGrid.h

//********************************** Banshee Engine (www.banshee3d.com) **************************************************//
//**************** Copyright (c) 2016 Marko Pintera ([email protected]). All rights reserved. **********************//
#pragma once

#include "BsRenderBeastPrerequisites.h"
#include "BsRendererMaterial.h"
#include "BsParamBlocks.h"
#include "BsVectorNI.h"

namespace bs { namespace ct
{
	class GPULightData;

	/** @addtogroup RenderBeast
	 *  @{
	 */

	BS_PARAM_BLOCK_BEGIN(LightGridParamDef)
		BS_PARAM_BLOCK_ENTRY(Vector3I, gLightOffsets)
		BS_PARAM_BLOCK_ENTRY(INT32, gNumCells)
		BS_PARAM_BLOCK_ENTRY(Vector3I, gGridSize)
		BS_PARAM_BLOCK_ENTRY(INT32, gMaxNumLightsPerCell)
		BS_PARAM_BLOCK_ENTRY(Vector2I, gGridPixelSize)
	BS_PARAM_BLOCK_END

	extern LightGridParamDef gLightGridParamDefDef;

	/** Shader that creates a linked list for each light grid cell, containing which light affects each cell. */
	class LightGridLLCreationMat : public RendererMaterial<LightGridLLCreationMat>
	{
		RMAT_DEF("LightGridLLCreation.bsl");

	public:
		LightGridLLCreationMat();

		/** Binds parameter buffers and prepares any internal buffers. Must be called before execute(). */
		void setParams(const Vector3I& gridSize, const SPtr<GpuParamBlockBuffer>& gridParams, 
					   const SPtr<GpuBuffer>& lightsBuffer);

		/** Binds the material for rendering, sets up per-camera parameters and executes it. */
		void execute(const RendererCamera& view);

		/** Returns the buffers generated by execute(). */
		void getOutputs(SPtr<GpuBuffer>& linkedListHeads, SPtr<GpuBuffer>& linkedList) const;
	private:
		GpuParamBuffer mLightBufferParam;
		GpuParamBuffer mLinkedListCounterParam;
		GpuParamBuffer mLinkedListHeadsParam;
		GpuParamBuffer mLinkedListParam;

		SPtr<GpuBuffer> mLinkedListCounter;
		SPtr<GpuBuffer> mLinkedListHeads;
		SPtr<GpuBuffer> mLinkedList;

		UINT32 mBufferNumCells;
		Vector3I mGridSize;
	};

	/** Shader that reduces the linked list created by LightGridLLCreationMat into a sequential array. */
	class LightGridLLReductionMat : public RendererMaterial<LightGridLLReductionMat>
	{
		RMAT_DEF("LightGridLLReduction.bsl");

	public:
		LightGridLLReductionMat();

		/** Binds parameter buffers and prepares any internal buffers. Must be called before execute(). */
		void setParams(const Vector3I& gridSize, const SPtr<GpuParamBlockBuffer>& gridParams, 
					   const SPtr<GpuBuffer>& linkedListHeads, const SPtr<GpuBuffer>& linkedList);

		/** Binds the material for renderingand executes it. */
		void execute(const RendererCamera& view);

		/** Returns the buffers generated by execute(). */
		void getOutputs(SPtr<GpuBuffer>& gridOffsetsAndSize, SPtr<GpuBuffer>& gridLightIndices) const;
	private:
		GpuParamBuffer mLinkedListHeadsParam;
		GpuParamBuffer mLinkedListParam;

		GpuParamBuffer mGridDataCounterParam;
		GpuParamBuffer mGridLightOffsetAndSizeParam;
		GpuParamBuffer mGridLightIndicesParam;

		SPtr<GpuBuffer> mGridDataCounter;
		SPtr<GpuBuffer> mGridLightOffsetAndSize;
		SPtr<GpuBuffer> mGridLightIndices;

		UINT32 mBufferNumCells;
		Vector3I mGridSize;
	};

	/**	
	 * Helper class that is used for generating a grid in view space, whose cells contain information about lights 
	 * affecting them. Used for forward rendering. 
	 */
	class LightGrid
	{
	public:
		LightGrid();

		/** Updates the light grid from the provided view. */
		void updateGrid(const RendererCamera& view, const GPULightData& lightData, bool noLighting);

		/** 
		 * Returns the buffers containing light indices per grid cell and global grid parameters. 
		 *
		 * @param[out]	gridOffsetsAndSize	Flattened array of grid cells, where each entry contains the number of lights
		 *									affecting that cell, and a index into the @p gridLightIndices buffer.
		 * @param[out]	gridLightIndices	A list of light indices. Each cell's indices start at specific position and
		 *									are placed sequentially one after another. Lookup into this array is done
		 *									through offset & size provided by @p gridOffsetsAndSize. 
		 * @param[out]	gridParams			Global grid parameter block.
		 */
		void getOutputs(SPtr<GpuBuffer>& gridOffsetsAndSize, SPtr<GpuBuffer>& gridLightIndices, 
						SPtr<GpuParamBlockBuffer>& gridParams) const;

	private:
		LightGridLLCreationMat mLLCreationMat;
		LightGridLLReductionMat mLLReductionMat;

		SPtr<GpuParamBlockBuffer> mGridParamBuffer;
	};

	/** @} */
}}