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PhysX4.1/physx/snippets/snippetbvhstructure/SnippetBVHStructure.cpp
2025-11-28 23:13:44 +05:30

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//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions
// are met:
// * Redistributions of source code must retain the above copyright
// notice, this list of conditions and the following disclaimer.
// * Redistributions in binary form must reproduce the above copyright
// notice, this list of conditions and the following disclaimer in the
// documentation and/or other materials provided with the distribution.
// * Neither the name of NVIDIA CORPORATION nor the names of its
// contributors may be used to endorse or promote products derived
// from this software without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS ''AS IS'' AND ANY
// EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
// IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
// PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
// CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
// EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
// PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
// PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
// OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
//
// Copyright (c) 2008-2021 NVIDIA Corporation. All rights reserved.
// Copyright (c) 2004-2008 AGEIA Technologies, Inc. All rights reserved.
// Copyright (c) 2001-2004 NovodeX AG. All rights reserved.
// ****************************************************************************
// This snippet illustrates the usage of PxBVHStructure
//
// It creates a large number of small sphere shapes forming a large sphere. Large sphere
// represents an actor and the actor is inserted into the scene with BVHStructure
// that is precomputed from all the small spheres. When an actor is insterted this
// way the scene queries against this object behave actor centric rather than shape
// centric.
// Each actor that is added with a BVHSctructure does not update any of its shape bounds
// within a pruning structure. It does update just the actor bounds and the query then
// goes into actors bounds pruner, then a local query is done against the shapes in the
// actor.
// For a dynamic actor consisting of a large amound of shapes there can be a significant
// performance benefits. During fetch results, there is no need to synchronize all
// shape bounds into scene query system. Also when a new AABB tree is build inside
// scene query system these actors shapes are not contained there.
// ****************************************************************************
#include <ctype.h>
#include "PxPhysicsAPI.h"
#include "../snippetcommon/SnippetPrint.h"
#include "../snippetcommon/SnippetPVD.h"
#include "../snippetutils/SnippetUtils.h"
using namespace physx;
PxDefaultAllocator gAllocator;
PxDefaultErrorCallback gErrorCallback;
PxFoundation* gFoundation = NULL;
PxPhysics* gPhysics = NULL;
PxCooking* gCooking = NULL;
PxDefaultCpuDispatcher* gDispatcher = NULL;
PxScene* gScene = NULL;
PxMaterial* gMaterial = NULL;
PxPvd* gPvd = NULL;
void createLargeSphere(const PxTransform& t, PxU32 density, PxReal largeRadius, PxReal radius, bool useAggregate)
{
PxRigidDynamic* body = gPhysics->createRigidDynamic(t);
// generate the sphere shapes
const float gStep = PxPi/float(density);
const float tStep = 2.0f*PxPi/float(density);
for(PxU32 i=0; i<density;i++)
{
for(PxU32 j=0;j<density;j++)
{
const float sinG = PxSin(gStep * i);
const float cosG = PxCos(gStep * i);
const float sinT = PxSin(tStep * j);
const float cosT = PxCos(tStep * j);
PxTransform localTm(PxVec3(largeRadius*sinG*cosT, largeRadius*sinG*sinT, largeRadius*cosG));
PxShape* shape = gPhysics->createShape(PxSphereGeometry(radius), *gMaterial);
shape->setLocalPose(localTm);
body->attachShape(*shape);
shape->release();
}
}
PxRigidBodyExt::updateMassAndInertia(*body, 10.0f);
// get the bounds from the actor, this can be done through a helper function in PhysX extensions
PxU32 numBounds = 0;
PxBounds3* bounds = PxRigidActorExt::getRigidActorShapeLocalBoundsList(*body, numBounds);
// setup the PxBVHStructureDesc, it does contain only the PxBounds3 data
PxBVHStructureDesc bvhDesc;
bvhDesc.bounds.count = numBounds;
bvhDesc.bounds.data = bounds;
bvhDesc.bounds.stride = sizeof(PxBounds3);
// cook the bvh structure
PxBVHStructure* bvh = gCooking->createBVHStructure(bvhDesc, gPhysics->getPhysicsInsertionCallback());
// release the memory allocated within extensions, the bounds are not required anymore
gAllocator.deallocate(bounds);
// add the actor to the scene and provide the bvh structure (regular path without aggregate usage)
if(!useAggregate)
gScene->addActor(*body, bvh);
// Note that when objects with large amound of shapes are created it is also
// recommended to create an aggregate from them, see the code below that would replace
// the gScene->addActor(*body, bvh)
if(useAggregate)
{
PxAggregate* aggregate = gPhysics->createAggregate(1, false);
aggregate->addActor(*body, bvh);
gScene->addAggregate(*aggregate);
}
// bvh can be released at this point, the precomputed BVH structure was copied to the SDK pruners.
bvh->release();
}
void initPhysics(bool /*interactive*/)
{
gFoundation = PxCreateFoundation(PX_PHYSICS_VERSION, gAllocator, gErrorCallback);
gPvd = PxCreatePvd(*gFoundation);
PxPvdTransport* transport = PxDefaultPvdSocketTransportCreate(PVD_HOST, 5425, 10);
gPvd->connect(*transport,PxPvdInstrumentationFlag::eALL);
gPhysics = PxCreatePhysics(PX_PHYSICS_VERSION, *gFoundation, PxTolerancesScale(),true,gPvd);
gCooking = PxCreateCooking(PX_PHYSICS_VERSION, *gFoundation, PxCookingParams(PxTolerancesScale()));
PxSceneDesc sceneDesc(gPhysics->getTolerancesScale());
sceneDesc.gravity = PxVec3(0.0f, -9.81f, 0.0f);
gDispatcher = PxDefaultCpuDispatcherCreate(2);
sceneDesc.cpuDispatcher = gDispatcher;
sceneDesc.filterShader = PxDefaultSimulationFilterShader;
gScene = gPhysics->createScene(sceneDesc);
PxPvdSceneClient* pvdClient = gScene->getScenePvdClient();
if(pvdClient)
{
pvdClient->setScenePvdFlag(PxPvdSceneFlag::eTRANSMIT_CONSTRAINTS, true);
pvdClient->setScenePvdFlag(PxPvdSceneFlag::eTRANSMIT_CONTACTS, true);
pvdClient->setScenePvdFlag(PxPvdSceneFlag::eTRANSMIT_SCENEQUERIES, true);
}
gMaterial = gPhysics->createMaterial(0.5f, 0.5f, 0.6f);
PxRigidStatic* groundPlane = PxCreatePlane(*gPhysics, PxPlane(0,1,0,0), *gMaterial);
gScene->addActor(*groundPlane);
for(PxU32 i = 0; i < 10; i++)
createLargeSphere(PxTransform(PxVec3(200.0f*i, .0f, 100.0f)), 50, 30.0f, 1.0f, false);
}
void stepPhysics(bool /*interactive*/)
{
gScene->simulate(1.0f/60.0f);
gScene->fetchResults(true);
}
void cleanupPhysics(bool /*interactive*/)
{
PX_RELEASE(gScene);
PX_RELEASE(gDispatcher);
PX_RELEASE(gPhysics);
PX_RELEASE(gCooking);
if(gPvd)
{
PxPvdTransport* transport = gPvd->getTransport();
gPvd->release(); gPvd = NULL;
PX_RELEASE(transport);
}
PX_RELEASE(gFoundation);
printf("SnippetBVHStructure done.\n");
}
void keyPress(unsigned char , const PxTransform& )
{
}
int snippetMain(int, const char*const*)
{
static const PxU32 frameCount = 50;
initPhysics(false);
for(PxU32 i=0; i<frameCount; i++)
stepPhysics(false);
cleanupPhysics(false);
return 0;
}