167 lines
9.2 KiB
C++
167 lines
9.2 KiB
C++
/********************************************************************************
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* ReactPhysics3D physics library, http://www.reactphysics3d.com *
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* Copyright (c) 2010-2018 Daniel Chappuis *
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*********************************************************************************
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* *
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* This software is provided 'as-is', without any express or implied warranty. *
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* In no event will the authors be held liable for any damages arising from the *
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* use of this software. *
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* *
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* Permission is granted to anyone to use this software for any purpose, *
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* including commercial applications, and to alter it and redistribute it *
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* freely, subject to the following restrictions: *
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* *
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* 1. The origin of this software must not be misrepresented; you must not claim *
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* that you wrote the original software. If you use this software in a *
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* product, an acknowledgment in the product documentation would be *
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* appreciated but is not required. *
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* *
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* 2. Altered source versions must be plainly marked as such, and must not be *
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* misrepresented as being the original software. *
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* *
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* 3. This notice may not be removed or altered from any source distribution. *
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* *
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********************************************************************************/
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// Libraries
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#include "CapsuleVsConvexPolyhedronAlgorithm.h"
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#include "SAT/SATAlgorithm.h"
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#include "GJK/GJKAlgorithm.h"
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#include "collision/shapes/CapsuleShape.h"
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#include "collision/shapes/ConvexPolyhedronShape.h"
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#include "collision/NarrowPhaseInfo.h"
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#include "collision/ContactPointInfo.h"
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#include <cassert>
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// We want to use the ReactPhysics3D namespace
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using namespace reactphysics3d;
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// Compute the narrow-phase collision detection between a capsule and a polyhedron
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// This technique is based on the "Robust Contact Creation for Physics Simulations" presentation
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// by Dirk Gregorius.
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bool CapsuleVsConvexPolyhedronAlgorithm::testCollision(NarrowPhaseInfo* narrowPhaseInfo, bool reportContacts,
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MemoryAllocator& memoryAllocator) {
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// First, we run the GJK algorithm
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GJKAlgorithm gjkAlgorithm;
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SATAlgorithm satAlgorithm(memoryAllocator);
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#ifdef IS_PROFILING_ACTIVE
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gjkAlgorithm.setProfiler(mProfiler);
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satAlgorithm.setProfiler(mProfiler);
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#endif
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// Get the last frame collision info
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LastFrameCollisionInfo* lastFrameCollisionInfo = narrowPhaseInfo->getLastFrameCollisionInfo();
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GJKAlgorithm::GJKResult result = gjkAlgorithm.testCollision(narrowPhaseInfo, reportContacts);
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lastFrameCollisionInfo->wasUsingGJK = true;
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lastFrameCollisionInfo->wasUsingSAT = false;
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assert(narrowPhaseInfo->collisionShape1->getType() == CollisionShapeType::CONVEX_POLYHEDRON ||
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narrowPhaseInfo->collisionShape2->getType() == CollisionShapeType::CONVEX_POLYHEDRON);
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assert(narrowPhaseInfo->collisionShape1->getType() == CollisionShapeType::CAPSULE ||
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narrowPhaseInfo->collisionShape2->getType() == CollisionShapeType::CAPSULE);
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// If we have found a contact point inside the margins (shallow penetration)
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if (result == GJKAlgorithm::GJKResult::COLLIDE_IN_MARGIN) {
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if (reportContacts) {
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// GJK has found a shallow contact. If the face of the polyhedron mesh is orthogonal to the
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// capsule inner segment and parallel to the contact point normal, we would like to create
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// two contact points instead of a single one (as in the deep contact case with SAT algorithm)
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// Get the contact point created by GJK
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assert(narrowPhaseInfo->contactPoints.size() > 0);
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ContactPointInfo*& contactPoint = narrowPhaseInfo->contactPoints[0];
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bool isCapsuleShape1 = narrowPhaseInfo->collisionShape1->getType() == CollisionShapeType::CAPSULE;
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// Get the collision shapes
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const CapsuleShape* capsuleShape = static_cast<const CapsuleShape*>(isCapsuleShape1 ? narrowPhaseInfo->collisionShape1 : narrowPhaseInfo->collisionShape2);
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const ConvexPolyhedronShape* polyhedron = static_cast<const ConvexPolyhedronShape*>(isCapsuleShape1 ? narrowPhaseInfo->collisionShape2 : narrowPhaseInfo->collisionShape1);
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// For each face of the polyhedron
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for (uint f = 0; f < polyhedron->getNbFaces(); f++) {
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const Transform polyhedronToWorld = isCapsuleShape1 ? narrowPhaseInfo->shape2ToWorldTransform : narrowPhaseInfo->shape1ToWorldTransform;
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const Transform capsuleToWorld = isCapsuleShape1 ? narrowPhaseInfo->shape1ToWorldTransform : narrowPhaseInfo->shape2ToWorldTransform;
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// Get the face normal
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const Vector3 faceNormal = polyhedron->getFaceNormal(f);
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Vector3 faceNormalWorld = polyhedronToWorld.getOrientation() * faceNormal;
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const Vector3 capsuleSegA(0, -capsuleShape->getHeight() * decimal(0.5), 0);
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const Vector3 capsuleSegB(0, capsuleShape->getHeight() * decimal(0.5), 0);
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Vector3 capsuleInnerSegmentDirection = capsuleToWorld.getOrientation() * (capsuleSegB - capsuleSegA);
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capsuleInnerSegmentDirection.normalize();
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bool isFaceNormalInDirectionOfContactNormal = faceNormalWorld.dot(contactPoint->normal) > decimal(0.0);
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bool isFaceNormalInContactDirection = (isCapsuleShape1 && !isFaceNormalInDirectionOfContactNormal) || (!isCapsuleShape1 && isFaceNormalInDirectionOfContactNormal);
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// If the polyhedron face normal is orthogonal to the capsule inner segment and parallel to the contact point normal and the face normal
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// is in direction of the contact normal (from the polyhedron point of view).
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if (isFaceNormalInContactDirection && areOrthogonalVectors(faceNormalWorld, capsuleInnerSegmentDirection)
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&& areParallelVectors(faceNormalWorld, contactPoint->normal)) {
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// Remove the previous contact point computed by GJK
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narrowPhaseInfo->resetContactPoints();
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const Transform capsuleToWorld = isCapsuleShape1 ? narrowPhaseInfo->shape1ToWorldTransform : narrowPhaseInfo->shape2ToWorldTransform;
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const Transform polyhedronToCapsuleTransform = capsuleToWorld.getInverse() * polyhedronToWorld;
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// Compute the end-points of the inner segment of the capsule
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const Vector3 capsuleSegA(0, -capsuleShape->getHeight() * decimal(0.5), 0);
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const Vector3 capsuleSegB(0, capsuleShape->getHeight() * decimal(0.5), 0);
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// Convert the inner capsule segment points into the polyhedron local-space
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const Transform capsuleToPolyhedronTransform = polyhedronToCapsuleTransform.getInverse();
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const Vector3 capsuleSegAPolyhedronSpace = capsuleToPolyhedronTransform * capsuleSegA;
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const Vector3 capsuleSegBPolyhedronSpace = capsuleToPolyhedronTransform * capsuleSegB;
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const Vector3 separatingAxisCapsuleSpace = polyhedronToCapsuleTransform.getOrientation() * faceNormal;
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if (isCapsuleShape1) {
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faceNormalWorld = -faceNormalWorld;
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}
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// Compute and create two contact points
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bool contactsFound = satAlgorithm.computeCapsulePolyhedronFaceContactPoints(f, capsuleShape->getRadius(), polyhedron, contactPoint->penetrationDepth,
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polyhedronToCapsuleTransform, faceNormalWorld, separatingAxisCapsuleSpace,
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capsuleSegAPolyhedronSpace, capsuleSegBPolyhedronSpace,
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narrowPhaseInfo, isCapsuleShape1);
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if (!contactsFound) {
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return false;
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}
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break;
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}
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}
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}
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lastFrameCollisionInfo->wasUsingSAT = false;
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lastFrameCollisionInfo->wasUsingGJK = false;
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// Return true
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return true;
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}
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// If we have overlap even without the margins (deep penetration)
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if (result == GJKAlgorithm::GJKResult::INTERPENETRATE) {
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// Run the SAT algorithm to find the separating axis and compute contact point
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bool isColliding = satAlgorithm.testCollisionCapsuleVsConvexPolyhedron(narrowPhaseInfo, reportContacts);
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lastFrameCollisionInfo->wasUsingGJK = false;
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lastFrameCollisionInfo->wasUsingSAT = true;
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return isColliding;
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}
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return false;
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}
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