283 lines
12 KiB
C++
283 lines
12 KiB
C++
// Redistribution and use in source and binary forms, with or without
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// modification, are permitted provided that the following conditions
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// are met:
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// * Redistributions of source code must retain the above copyright
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// notice, this list of conditions and the following disclaimer.
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// * Redistributions in binary form must reproduce the above copyright
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// notice, this list of conditions and the following disclaimer in the
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// documentation and/or other materials provided with the distribution.
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// * Neither the name of NVIDIA CORPORATION nor the names of its
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// contributors may be used to endorse or promote products derived
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// from this software without specific prior written permission.
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//
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// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS ''AS IS'' AND ANY
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// EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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// IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
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// PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
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// CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
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// EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
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// PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
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// PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
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// OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
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// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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//
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// Copyright (c) 2008-2025 NVIDIA Corporation. All rights reserved.
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// Copyright (c) 2004-2008 AGEIA Technologies, Inc. All rights reserved.
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// Copyright (c) 2001-2004 NovodeX AG. All rights reserved.
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// *****************************************************************************************
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// This snippet demonstrates the use of a spatial tendon to actuate a symmetric articulation
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// *****************************************************************************************
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#include <ctype.h>
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#include "PxPhysicsAPI.h"
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#include "../snippetutils/SnippetUtils.h"
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#include "../snippetcommon/SnippetPrint.h"
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#include "../snippetcommon/SnippetPVD.h"
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using namespace physx;
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static PxDefaultAllocator gAllocator;
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static PxDefaultErrorCallback gErrorCallback;
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static PxFoundation* gFoundation = NULL;
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static PxPhysics* gPhysics = NULL;
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static PxDefaultCpuDispatcher* gDispatcher = NULL;
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static PxScene* gScene = NULL;
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static PxMaterial* gMaterial = NULL;
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static PxPvd* gPvd = NULL;
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static PxArticulationReducedCoordinate* gArticulations[2] = { NULL };
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static const PxReal gGravity = 9.81f;
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static const PxReal gLinkHalfLength = 0.5f;
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PxRigidStatic** getAttachments()
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{
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static PxRigidStatic* attachments[6] = { NULL };
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return attachments;
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}
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static void createSpatialTendonArticulation(PxArticulationReducedCoordinate* articulation,
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PxRigidStatic** attachmentRigidStatics,
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const PxVec3 offset)
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{
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// link geometry and density:
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const PxVec3 linkExtents(gLinkHalfLength, 0.05f, 0.05f);
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const PxBoxGeometry linkGeom = PxBoxGeometry(linkExtents);
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const PxReal density = 1000.0f;
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articulation->setArticulationFlags(PxArticulationFlag::eFIX_BASE);
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articulation->setSolverIterationCounts(10, 1);
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PxTransform pose = PxTransform(offset, PxQuat(PxIdentity));
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pose.p.y += 3.0f;
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PxArticulationLink* baseLink = articulation->createLink(NULL, pose);
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PxRigidActorExt::createExclusiveShape(*baseLink, linkGeom, *gMaterial);
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PxRigidBodyExt::updateMassAndInertia(*baseLink, density);
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pose.p.x -= linkExtents.x * 2.0f;
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PxArticulationLink* leftLink = articulation->createLink(baseLink, pose);
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PxRigidActorExt::createExclusiveShape(*leftLink, linkGeom, *gMaterial);
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PxRigidBodyExt::updateMassAndInertia(*leftLink, density);
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pose.p.x += linkExtents.x * 4.0f;
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PxArticulationLink* rightLink = articulation->createLink(baseLink, pose);
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PxRigidActorExt::createExclusiveShape(*rightLink, linkGeom, *gMaterial);
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PxRigidBodyExt::updateMassAndInertia(*rightLink, density);
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// setup revolute joints:
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{
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PxArticulationJointReducedCoordinate* joint = leftLink->getInboundJoint();
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if(joint)
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{
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PxVec3 parentOffset(-linkExtents.x, 0.0f, 0.0f);
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PxVec3 childOffset(linkExtents.x, 0.0f, 0.0f);
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joint->setParentPose(PxTransform(parentOffset, PxQuat(PxIdentity)));
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joint->setChildPose(PxTransform(childOffset, PxQuat(PxIdentity)));
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joint->setJointType(PxArticulationJointType::eREVOLUTE);
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joint->setMotion(PxArticulationAxis::eSWING2, PxArticulationMotion::eFREE);
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}
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}
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{
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PxArticulationJointReducedCoordinate* joint = rightLink->getInboundJoint();
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if(joint)
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{
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PxVec3 parentOffset(linkExtents.x, 0.0f, 0.0f);
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PxVec3 childOffset(-linkExtents.x, 0.0f, 0.0f);
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joint->setParentPose(PxTransform(parentOffset, PxQuat(PxIdentity)));
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joint->setChildPose(PxTransform(childOffset, PxQuat(PxIdentity)));
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joint->setJointType(PxArticulationJointType::eREVOLUTE);
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joint->setMotion(PxArticulationAxis::eSWING2, PxArticulationMotion::eFREE);
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}
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}
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// tendon stiffness sizing:
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// scale articulation geometry:
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// r: root attachment on left moving link
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// a: attachment on fixed-base link
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// l: leaf attachment on right moving link
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// o: revolute joint
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// a
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//
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// ----r----o---------o----l----
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// The root and leaf attachment are at the center of mass of the moving links.
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// The attachment on the fixed-base link is a link halfLength above the link.
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// Therefore, the (rest)length of the tendon r-a-l when both joints are at zero is:
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// 2 * sqrt((2 * gLinkHalfLength)^2 + gLinkHalfLength^2) = 2 * gLinkHalfLength * sqrt(5)
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const PxReal restLength = 2.0f * gLinkHalfLength * PxSqrt(5.0f);
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// The goal is to have the revolute joints deviate just a few degrees from the horizontal
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// and we compute the length of the tendon at that angle:
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const PxReal deviationAngle = 3.0f * PxPi / 180.0f;
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// Distances from the base-link attachment to the root and leaf attachments
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const PxReal verticalDistance = gLinkHalfLength * (1.0f + PxSin(deviationAngle));
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const PxReal horizontalDistance = gLinkHalfLength * (1.0f + PxCos(deviationAngle));
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const PxReal deviatedLength = 2.0f * PxSqrt(verticalDistance * verticalDistance + horizontalDistance * horizontalDistance);
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// At rest, the force on the leaf attachment is (deviatedLength - restLength) * tendonStiffness.
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// This force needs to be equal to the gravity force acting on the link. An equal and opposing
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// (in the direction of the tendon) force acts on the root link and will hold that link up.
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// In order to calculate the tendon stiffness that produces that force, we consider the forces
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// and attachment geometry at zero joint angles.
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const PxReal linkMass = baseLink->getMass();
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const PxReal gravityForce = gGravity * linkMass;
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// Project onto tendon at rest length / with joints at zero angle
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const PxReal tendonForce = gravityForce * PxSqrt(5.0f); // gravityForce * 0.5f * restLength / halfLength
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// and compute stiffness to get tendon force at deviated length to hold the link:
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const PxReal tendonStiffness = tendonForce / (deviatedLength - restLength);
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const PxReal tendonDamping = 0.3f * tendonStiffness;
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PxArticulationSpatialTendon* tendon = articulation->createSpatialTendon();
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tendon->setStiffness(tendonStiffness);
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tendon->setDamping(tendonDamping);
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PxArticulationAttachment* rootAttachment = tendon->createAttachment(NULL, 1.0f, PxVec3(0.0f), leftLink);
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PxArticulationAttachment* baseAttachment = tendon->createAttachment(rootAttachment, 1.0f, PxVec3(0.0f, gLinkHalfLength, 0.0f), baseLink);
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PxArticulationAttachment* leafAttachment = tendon->createAttachment(baseAttachment, 1.0f, PxVec3(0.0f), rightLink);
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leafAttachment->setRestLength(restLength);
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// create attachment render shapes
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attachmentRigidStatics[0] = gPhysics->createRigidStatic(baseLink->getGlobalPose() * PxTransform(PxVec3(0.0f, gLinkHalfLength, 0.0f), PxQuat(PxIdentity)));
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attachmentRigidStatics[1] = gPhysics->createRigidStatic(leftLink->getGlobalPose());
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attachmentRigidStatics[2] = gPhysics->createRigidStatic(rightLink->getGlobalPose());
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PxSphereGeometry attachmentGeom(linkExtents.y * 1.5f); // slightly bigger than links to see the attachment on the moving links
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PxShape* attachmentShape = gPhysics->createShape(attachmentGeom, *gMaterial, false, PxShapeFlags(0));
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for(PxU32 i = 0; i < 3; ++i)
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{
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PxRigidStatic* attachment = attachmentRigidStatics[i];
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attachment->setActorFlag(PxActorFlag::eDISABLE_SIMULATION, true); // attachments are viz only
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attachment->attachShape(*attachmentShape);
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}
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// add articulation to scene:
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gScene->addArticulation(*articulation);
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}
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void initPhysics(bool /*interactive*/)
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{
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gFoundation = PxCreateFoundation(PX_PHYSICS_VERSION, gAllocator, gErrorCallback);
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gPvd = PxCreatePvd(*gFoundation);
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PxPvdTransport* transport = PxDefaultPvdSocketTransportCreate(PVD_HOST, 5425, 10);
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gPvd->connect(*transport, PxPvdInstrumentationFlag::eALL);
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gPhysics = PxCreatePhysics(PX_PHYSICS_VERSION, *gFoundation, PxTolerancesScale(), true, gPvd);
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PxInitExtensions(*gPhysics, gPvd);
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PxSceneDesc sceneDesc(gPhysics->getTolerancesScale());
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sceneDesc.gravity = PxVec3(0.0f, -gGravity, 0.0f);
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PxU32 numCores = SnippetUtils::getNbPhysicalCores();
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gDispatcher = PxDefaultCpuDispatcherCreate(numCores == 0 ? 0 : numCores - 1);
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sceneDesc.cpuDispatcher = gDispatcher;
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sceneDesc.filterShader = PxDefaultSimulationFilterShader;
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sceneDesc.solverType = PxSolverType::eTGS;
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sceneDesc.filterShader = PxDefaultSimulationFilterShader;
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gScene = gPhysics->createScene(sceneDesc);
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gMaterial = gPhysics->createMaterial(0.5f, 0.5f, 0.f);
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gArticulations[0] = gPhysics->createArticulationReducedCoordinate();
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createSpatialTendonArticulation(gArticulations[0], getAttachments(), PxVec3(0.0f));
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gArticulations[1] = gPhysics->createArticulationReducedCoordinate();
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createSpatialTendonArticulation(gArticulations[1], &getAttachments()[3], PxVec3(0.0f, 0.0f, 2.0f));
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}
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void stepPhysics(bool /*interactive*/)
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{
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const PxReal dt = 1.0f / 60.f;
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static PxReal time = 0.0f;
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// update articulation that actuates via tendon-length offset:
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{
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const PxReal amplitude = 0.3f;
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// move at 0.25 Hz, and offset sinusoid by an amplitude
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const PxReal offset = amplitude * (1.0f + PxSin(time * PxTwoPi * 0.25f - PxPiDivTwo));
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PxArticulationSpatialTendon* tendon = NULL;
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gArticulations[0]->getSpatialTendons(&tendon, 1, 0);
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tendon->setOffset(offset);
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PxArticulationLink* links[3];
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gArticulations[0]->getLinks(links, 3, 0);
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getAttachments()[1]->setGlobalPose(links[1]->getGlobalPose());
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getAttachments()[2]->setGlobalPose(links[2]->getGlobalPose());
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}
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// update articulation that actuates via base link attachment relative pose
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{
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const PxReal amplitude = 0.2f;
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// move at 0.25 Hz, and offset sinusoid by an amplitude
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const PxReal offset = gLinkHalfLength + amplitude * (1.0f + PxSin(time * PxTwoPi * 0.25f - PxPiDivTwo));
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PxArticulationSpatialTendon* tendon = NULL;
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gArticulations[1]->getSpatialTendons(&tendon, 1, 0);
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PxArticulationAttachment* baseAttachment = NULL;
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tendon->getAttachments(&baseAttachment, 1, 1);
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baseAttachment->setRelativeOffset(PxVec3(0.f, offset, 0.f));
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gArticulations[1]->wakeUp(); // wake up articulation (relative offset setting does not wake)
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PxArticulationLink* links[3];
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gArticulations[1]->getLinks(links, 3, 0);
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PxTransform attachmentPose = links[0]->getGlobalPose();
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attachmentPose.p.y += offset;
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getAttachments()[3]->setGlobalPose(attachmentPose);
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getAttachments()[4]->setGlobalPose(links[1]->getGlobalPose());
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getAttachments()[5]->setGlobalPose(links[2]->getGlobalPose());
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}
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gScene->simulate(dt);
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gScene->fetchResults(true);
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time += dt;
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}
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void cleanupPhysics(bool /*interactive*/)
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{
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gArticulations[0]->release();
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gArticulations[1]->release();
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PX_RELEASE(gScene);
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PX_RELEASE(gDispatcher);
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PX_RELEASE(gPhysics);
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if (gPvd)
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{
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PxPvdTransport* transport = gPvd->getTransport();
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PX_RELEASE(gPvd);
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PX_RELEASE(transport);
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}
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PxCloseExtensions();
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PX_RELEASE(gFoundation);
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printf("SnippetSpatialTendon done.\n");
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}
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int snippetMain(int, const char*const*)
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{
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#ifdef RENDER_SNIPPET
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extern void renderLoop();
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renderLoop();
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#else
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static const PxU32 frameCount = 100;
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initPhysics(false);
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for(PxU32 i = 0; i < frameCount; i++)
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stepPhysics(false);
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cleanupPhysics(false);
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#endif
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return 0;
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}
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