// This code contains NVIDIA Confidential Information and is disclosed to you
// under a form of NVIDIA software license agreement provided separately to you.
//
// Notice
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// proprietary rights in and to this software and related documentation and
// any modifications thereto. Any use, reproduction, disclosure, or
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// license agreement from NVIDIA Corporation is strictly prohibited.
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// ALL NVIDIA DESIGN SPECIFICATIONS, CODE ARE PROVIDED "AS IS.". NVIDIA MAKES
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// THE MATERIALS, AND EXPRESSLY DISCLAIMS ALL IMPLIED WARRANTIES OF NONINFRINGEMENT,
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// However, NVIDIA Corporation assumes no responsibility for the consequences of use of such
// information or for any infringement of patents or other rights of third parties that may
// result from its use. No license is granted by implication or otherwise under any patent
// or patent rights of NVIDIA Corporation. Details are subject to change without notice.
// This code supersedes and replaces all information previously supplied.
// NVIDIA Corporation products are not authorized for use as critical
// components in life support devices or systems without express written approval of
// NVIDIA Corporation.
//
// Copyright (c) 2008-2016 NVIDIA Corporation. All rights reserved.
// Copyright (c) 2004-2008 AGEIA Technologies, Inc. All rights reserved.
// Copyright (c) 2001-2004 NovodeX AG. All rights reserved.
#ifndef PT_DYNAMIC_HELPER_H
#define PT_DYNAMIC_HELPER_H

#include "PxPhysXConfig.h"
#if PX_USE_PARTICLE_SYSTEM_API

#include "PtDynamicsKernels.h"
#include "PtSpatialHash.h"
#include "PtDynamicsTempBuffers.h"

namespace physx
{

namespace Pt
{

//-------------------------------------------------------------------------------------------------------------------//

PX_FORCE_INLINE void updateParticlesPrePass(const SphUpdateType::Enum updateType, PxVec3* forceBuf, Particle* particles,
                                            PxU32 numParticles, const DynamicsParameters& params)
{
	if(updateType == SphUpdateType::DENSITY)
	{
		for(PxU32 i = 0; i < numParticles; ++i)
		{
			Pt::Particle& particle = particles[i];

			// Initialize particle densities with self density value
			particle.density = params.selfDensity;
			forceBuf[i] = PxVec3(0);
		}
	}
}

//-------------------------------------------------------------------------------------------------------------------//

PX_FORCE_INLINE void updateParticlesPostPass(const SphUpdateType::Enum updateType, PxVec3* forceBuf,
                                             Particle* particles, PxU32 numParticles, const DynamicsParameters& params)
{
	if(updateType == SphUpdateType::FORCE)
	{
		for(PxU32 i = 0; i < numParticles; ++i)
		{
			Particle& particle = particles[i];

			forceBuf[i] *= params.scaleToWorld * (1.0f / particle.density);
		}
	}
}

//-------------------------------------------------------------------------------------------------------------------//

/*!
Given a cell hash table, find neighboring cells and compute particle interactions.
*/
void updateCellsSubpacket(SphUpdateType::Enum updateType, PxVec3* __restrict forceBuf, Particle* __restrict particles,
                          const ParticleCell* __restrict cells, const PxU32* __restrict particleIndices,
                          const PxU32 numCellHashBuckets, const DynamicsParameters& params,
                          DynamicsTempBuffers& tempBuffers)
{
	PX_ASSERT(particles);
	PX_ASSERT(cells);
	PX_ASSERT(particleIndices);

	const ParticleCell* neighborCells[13];

	for(PxU32 c = 0; c < numCellHashBuckets; c++)
	{
		const ParticleCell& cell = cells[c];

		if(cell.numParticles == PX_INVALID_U32)
			continue;

		GridCellVector coords(cell.coords);

		//
		// To process each pair of neighboring cells only once, a special neighborhood layout can be
		// used. Thus, we do not need to consider all 26 neighbors of a cell but only half of them.
		// Going through the list of cells, a cell X might not be aware of a neighboring cell Y with
		// this layout, however, since cell Y in turn is aware of cell X the pair will still be processed
		// at the end.
		//

		// Complete back plane
		PxU32 cellIdx;

		PxI16 neighbor[13][3] = { { -1, -1, -1 },
			                      { 0, -1, -1 },
			                      { 1, -1, -1 },
			                      { -1, 0, -1 },
			                      { 0, 0, -1 },
			                      { 1, 0, -1 },
			                      { -1, 1, -1 },
			                      { 0, 1, -1 },
			                      { 1, 1, -1 },
			                      { 1, 0, 0 },
			                      { -1, 1, 0 },
			                      { 0, 1, 0 },
			                      { 1, 1, 0 } };

		for(PxU32 n = 0; n < 13; n++)
		{
			neighborCells[n] = SpatialHash::findConstCell(
			    cellIdx, GridCellVector(coords.x + neighbor[n][0], coords.y + neighbor[n][1], coords.z + neighbor[n][2]),
			    cells, numCellHashBuckets);
		}

		// Compute interaction between particles inside the current cell
		// These calls still produce a lot of LHS. Going from two way to one way updates didn't help. TODO, more
		// investigation.
		for(PxU32 p = 1; p < cell.numParticles; p++)
		{
			updateParticleGroupPair(forceBuf, forceBuf, particles, particles,
			                        particleIndices + cell.firstParticle + p - 1, 1,
			                        particleIndices + cell.firstParticle + p, cell.numParticles - p, true,
			                        updateType == SphUpdateType::DENSITY, params, tempBuffers.simdPositionsSubpacket,
			                        tempBuffers.indexStream);
		}

		// Compute interaction between particles of current cell and neighboring cells
		PxU32 srcIndexCount = 0;

		for(PxU32 n = 0; n < 13; n++)
		{
			if(!neighborCells[n])
				continue;

			const ParticleCell* nCell = neighborCells[n];

			for(PxU32 i = nCell->firstParticle, end = nCell->firstParticle + nCell->numParticles; i < end; i++)
				tempBuffers.mergedIndices[srcIndexCount++] = particleIndices[i];
		}

		if(srcIndexCount > 0)
		{
			updateParticleGroupPair(forceBuf, forceBuf, particles, particles, particleIndices + cell.firstParticle,
			                        cell.numParticles, tempBuffers.mergedIndices, srcIndexCount, true,
			                        updateType == SphUpdateType::DENSITY, params, tempBuffers.simdPositionsSubpacket,
			                        tempBuffers.indexStream);
		}
	}
}

//-------------------------------------------------------------------------------------------------------------------//

/*!
Given two subpackets, i.e., their cell hash tables and particle arrays, find for each cell of the first subpacket
the neighboring cells within the second subpacket and compute particle interactions for these neighboring cells.
*/
void updateCellsSubpacketPair(SphUpdateType::Enum updateType, PxVec3* __restrict forceBufA, PxVec3* __restrict forceBufB,
                              Particle* __restrict particlesSpA, Particle* __restrict particlesSpB,
                              const ParticleCell* __restrict cellsSpA, const ParticleCell* __restrict cellsSpB,
                              const PxU32* __restrict particleIndicesSpA, const PxU32* __restrict particleIndicesSpB,
                              const PxU32 numCellHashBucketsA, const PxU32 numCellHashBucketsB, bool twoWayUpdate,
                              const DynamicsParameters& params, DynamicsTempBuffers& tempBuffers, bool swapAB)
{
	PX_ASSERT(particlesSpA);
	PX_ASSERT(particlesSpB);
	PX_ASSERT(cellsSpA);
	PX_ASSERT(cellsSpB);
	PX_ASSERT(particleIndicesSpA);
	PX_ASSERT(particleIndicesSpB);

	const ParticleCell* __restrict srcCell;
	const ParticleCell* __restrict dstCell;
	const PxU32* __restrict dstIndices;
	PxU32 srcBuckets, dstBuckets;

	if(swapAB)
	{
		srcCell = cellsSpB;
		srcBuckets = numCellHashBucketsB;

		dstCell = cellsSpA;
		dstIndices = particleIndicesSpA;
		dstBuckets = numCellHashBucketsA;
	}
	else
	{
		srcCell = cellsSpA;
		srcBuckets = numCellHashBucketsA;

		dstCell = cellsSpB;
		dstIndices = particleIndicesSpB;
		dstBuckets = numCellHashBucketsB;
	}

	const ParticleCell* neighborCells[27];

	// For the cells of the subpacket A find neighboring cells in the subpacket B.
	const ParticleCell* pcell_end = srcCell + srcBuckets;
	for(const ParticleCell* pcell = srcCell; pcell < pcell_end; pcell++)
	{
		if(pcell->numParticles != PX_INVALID_U32)
		{
			GridCellVector coords(pcell->coords);

			//
			// Check the 26 neighboring cells plus the cell with the same coordinates but inside the other subpacket
			//

			// Back plane
			PxU32 cellIdx;
			PxI16 neighbor[27][3] = { { -1, -1, -1 },
				                      { 0, -1, -1 },
				                      { 1, -1, -1 },
				                      { -1, 0, -1 },
				                      { 0, 0, -1 },
				                      { 1, 0, -1 },
				                      { -1, 1, -1 },
				                      { 0, 1, -1 },
				                      { 1, 1, -1 },
				                      { -1, -1, 0 },
				                      { 0, -1, 0 },
				                      { 1, -1, 0 },
				                      { -1, 0, 0 },
				                      { 0, 0, 0 },
				                      { 1, 0, 0 },
				                      { -1, 1, 0 },
				                      { 0, 1, 0 },
				                      { 1, 1, 0 },
				                      { -1, -1, 1 },
				                      { 0, -1, 1 },
				                      { 1, -1, 1 },
				                      { -1, 0, 1 },
				                      { 0, 0, 1 },
				                      { 1, 0, 1 },
				                      { -1, 1, 1 },
				                      { 0, 1, 1 },
				                      { 1, 1, 1 } };

			for(PxU32 n = 0; n < 27; n++)
			{
				neighborCells[n] = SpatialHash::findConstCell(
				    cellIdx,
				    GridCellVector(coords.x + neighbor[n][0], coords.y + neighbor[n][1], coords.z + neighbor[n][2]),
				    dstCell, dstBuckets);
			}

			// Compute interaction between particles of current cell and neighboring cells
			PxU32 indexCount = 0;

			for(PxU32 n = 0; n < 27; n++)
			{
				if(!neighborCells[n])
					continue;

				const ParticleCell* nCell = neighborCells[n];

				for(PxU32 i = nCell->firstParticle, end = nCell->firstParticle + nCell->numParticles; i < end; i++)
					tempBuffers.mergedIndices[indexCount++] = dstIndices[i];
			}

			if(indexCount > 0)
			{

				if(swapAB)
				{
					updateParticleGroupPair(forceBufA, forceBufB, particlesSpA, particlesSpB, tempBuffers.mergedIndices,
					                        indexCount, particleIndicesSpB + pcell->firstParticle, pcell->numParticles,
					                        twoWayUpdate, updateType == SphUpdateType::DENSITY, params,
					                        tempBuffers.simdPositionsSubpacket, tempBuffers.indexStream);
				}
				else
				{
					updateParticleGroupPair(forceBufA, forceBufB, particlesSpA, particlesSpB,
					                        particleIndicesSpA + pcell->firstParticle, pcell->numParticles,
					                        tempBuffers.mergedIndices, indexCount, twoWayUpdate,
					                        updateType == SphUpdateType::DENSITY, params,
					                        tempBuffers.simdPositionsSubpacket, tempBuffers.indexStream);
				}
			}
		}
	}
}

//-------------------------------------------------------------------------------------------------------------------//

PX_FORCE_INLINE void normalizeParticleDensity(Particle& particle, const PxF32 selfDensity,
                                              const PxF32 densityNormalizationFactor)
{
	// normalize density
	particle.density = (particle.density - selfDensity) * densityNormalizationFactor;
}

//-------------------------------------------------------------------------------------------------------------------//

} // namespace Pt
} // namespace physx

#endif // PX_USE_PARTICLE_SYSTEM_API
#endif // PT_DYNAMIC_HELPER_H