422 lines
12 KiB
C++
422 lines
12 KiB
C++
/*
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Bullet Continuous Collision Detection and Physics Library
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* The b2CollidePolygons routines are Copyright (c) 2006-2007 Erin Catto http://www.gphysics.com
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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 use of this software.
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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 freely,
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subject to the following restrictions:
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1. The origin of this software must not be misrepresented; you must not claim that you wrote the original software. If you use this software in a product, an acknowledgment in the product documentation would be appreciated but is not required.
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2. Altered source versions must be plainly marked as such, and must not be misrepresented as being the original software.
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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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///btBox2dBox2dCollisionAlgorithm, with modified b2CollidePolygons routines from the Box2D library.
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///The modifications include: switching from b2Vec to btVector3, redefinition of b2Dot, b2Cross
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#include "btBox2dBox2dCollisionAlgorithm.h"
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#include "BulletCollision/CollisionDispatch/btCollisionDispatcher.h"
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#include "BulletCollision/CollisionShapes/btBoxShape.h"
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#include "BulletCollision/CollisionDispatch/btCollisionObject.h"
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#include "BulletCollision/CollisionDispatch/btBoxBoxDetector.h"
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#include "BulletCollision/CollisionShapes/btBox2dShape.h"
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#include "BulletCollision/CollisionDispatch/btCollisionObjectWrapper.h"
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#define USE_PERSISTENT_CONTACTS 1
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btBox2dBox2dCollisionAlgorithm::btBox2dBox2dCollisionAlgorithm(btPersistentManifold* mf,const btCollisionAlgorithmConstructionInfo& ci,const btCollisionObjectWrapper* obj0Wrap,const btCollisionObjectWrapper* obj1Wrap)
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: btActivatingCollisionAlgorithm(ci,obj0Wrap,obj1Wrap),
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m_ownManifold(false),
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m_manifoldPtr(mf)
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{
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if (!m_manifoldPtr && m_dispatcher->needsCollision(obj0Wrap->getCollisionObject(),obj1Wrap->getCollisionObject()))
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{
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m_manifoldPtr = m_dispatcher->getNewManifold(obj0Wrap->getCollisionObject(),obj1Wrap->getCollisionObject());
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m_ownManifold = true;
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}
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}
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btBox2dBox2dCollisionAlgorithm::~btBox2dBox2dCollisionAlgorithm()
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{
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if (m_ownManifold)
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{
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if (m_manifoldPtr)
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m_dispatcher->releaseManifold(m_manifoldPtr);
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}
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}
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void b2CollidePolygons(btManifoldResult* manifold, const btBox2dShape* polyA, const btTransform& xfA, const btBox2dShape* polyB, const btTransform& xfB);
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//#include <stdio.h>
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void btBox2dBox2dCollisionAlgorithm::processCollision (const btCollisionObjectWrapper* body0Wrap,const btCollisionObjectWrapper* body1Wrap,const btDispatcherInfo& dispatchInfo,btManifoldResult* resultOut)
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{
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if (!m_manifoldPtr)
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return;
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const btBox2dShape* box0 = (const btBox2dShape*)body0Wrap->getCollisionShape();
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const btBox2dShape* box1 = (const btBox2dShape*)body1Wrap->getCollisionShape();
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resultOut->setPersistentManifold(m_manifoldPtr);
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b2CollidePolygons(resultOut,box0,body0Wrap->getWorldTransform(),box1,body1Wrap->getWorldTransform());
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// refreshContactPoints is only necessary when using persistent contact points. otherwise all points are newly added
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if (m_ownManifold)
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{
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resultOut->refreshContactPoints();
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}
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}
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btScalar btBox2dBox2dCollisionAlgorithm::calculateTimeOfImpact(btCollisionObject* /*body0*/,btCollisionObject* /*body1*/,const btDispatcherInfo& /*dispatchInfo*/,btManifoldResult* /*resultOut*/)
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{
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//not yet
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return 1.f;
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}
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struct ClipVertex
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{
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btVector3 v;
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int id;
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//b2ContactID id;
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//b2ContactID id;
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};
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#define b2Dot(a,b) (a).dot(b)
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#define b2Mul(a,b) (a)*(b)
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#define b2MulT(a,b) (a).transpose()*(b)
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#define b2Cross(a,b) (a).cross(b)
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#define btCrossS(a,s) btVector3(s * a.getY(), -s * a.getX(),0.f)
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int b2_maxManifoldPoints =2;
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static int ClipSegmentToLine(ClipVertex vOut[2], ClipVertex vIn[2],
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const btVector3& normal, btScalar offset)
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{
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// Start with no output points
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int numOut = 0;
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// Calculate the distance of end points to the line
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btScalar distance0 = b2Dot(normal, vIn[0].v) - offset;
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btScalar distance1 = b2Dot(normal, vIn[1].v) - offset;
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// If the points are behind the plane
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if (distance0 <= 0.0f) vOut[numOut++] = vIn[0];
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if (distance1 <= 0.0f) vOut[numOut++] = vIn[1];
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// If the points are on different sides of the plane
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if (distance0 * distance1 < 0.0f)
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{
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// Find intersection point of edge and plane
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btScalar interp = distance0 / (distance0 - distance1);
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vOut[numOut].v = vIn[0].v + interp * (vIn[1].v - vIn[0].v);
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if (distance0 > 0.0f)
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{
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vOut[numOut].id = vIn[0].id;
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}
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else
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{
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vOut[numOut].id = vIn[1].id;
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}
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++numOut;
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}
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return numOut;
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}
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// Find the separation between poly1 and poly2 for a give edge normal on poly1.
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static btScalar EdgeSeparation(const btBox2dShape* poly1, const btTransform& xf1, int edge1,
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const btBox2dShape* poly2, const btTransform& xf2)
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{
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const btVector3* vertices1 = poly1->getVertices();
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const btVector3* normals1 = poly1->getNormals();
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int count2 = poly2->getVertexCount();
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const btVector3* vertices2 = poly2->getVertices();
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btAssert(0 <= edge1 && edge1 < poly1->getVertexCount());
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// Convert normal from poly1's frame into poly2's frame.
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btVector3 normal1World = b2Mul(xf1.getBasis(), normals1[edge1]);
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btVector3 normal1 = b2MulT(xf2.getBasis(), normal1World);
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// Find support vertex on poly2 for -normal.
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int index = 0;
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btScalar minDot = BT_LARGE_FLOAT;
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if( count2 > 0 )
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index = (int) normal1.minDot( vertices2, count2, minDot);
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btVector3 v1 = b2Mul(xf1, vertices1[edge1]);
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btVector3 v2 = b2Mul(xf2, vertices2[index]);
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btScalar separation = b2Dot(v2 - v1, normal1World);
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return separation;
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}
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// Find the max separation between poly1 and poly2 using edge normals from poly1.
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static btScalar FindMaxSeparation(int* edgeIndex,
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const btBox2dShape* poly1, const btTransform& xf1,
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const btBox2dShape* poly2, const btTransform& xf2)
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{
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int count1 = poly1->getVertexCount();
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const btVector3* normals1 = poly1->getNormals();
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// Vector pointing from the centroid of poly1 to the centroid of poly2.
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btVector3 d = b2Mul(xf2, poly2->getCentroid()) - b2Mul(xf1, poly1->getCentroid());
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btVector3 dLocal1 = b2MulT(xf1.getBasis(), d);
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// Find edge normal on poly1 that has the largest projection onto d.
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int edge = 0;
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btScalar maxDot;
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if( count1 > 0 )
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edge = (int) dLocal1.maxDot( normals1, count1, maxDot);
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// Get the separation for the edge normal.
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btScalar s = EdgeSeparation(poly1, xf1, edge, poly2, xf2);
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if (s > 0.0f)
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{
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return s;
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}
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// Check the separation for the previous edge normal.
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int prevEdge = edge - 1 >= 0 ? edge - 1 : count1 - 1;
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btScalar sPrev = EdgeSeparation(poly1, xf1, prevEdge, poly2, xf2);
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if (sPrev > 0.0f)
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{
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return sPrev;
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}
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// Check the separation for the next edge normal.
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int nextEdge = edge + 1 < count1 ? edge + 1 : 0;
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btScalar sNext = EdgeSeparation(poly1, xf1, nextEdge, poly2, xf2);
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if (sNext > 0.0f)
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{
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return sNext;
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}
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// Find the best edge and the search direction.
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int bestEdge;
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btScalar bestSeparation;
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int increment;
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if (sPrev > s && sPrev > sNext)
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{
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increment = -1;
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bestEdge = prevEdge;
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bestSeparation = sPrev;
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}
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else if (sNext > s)
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{
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increment = 1;
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bestEdge = nextEdge;
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bestSeparation = sNext;
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}
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else
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{
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*edgeIndex = edge;
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return s;
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}
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// Perform a local search for the best edge normal.
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for ( ; ; )
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{
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if (increment == -1)
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edge = bestEdge - 1 >= 0 ? bestEdge - 1 : count1 - 1;
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else
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edge = bestEdge + 1 < count1 ? bestEdge + 1 : 0;
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s = EdgeSeparation(poly1, xf1, edge, poly2, xf2);
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if (s > 0.0f)
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{
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return s;
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}
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if (s > bestSeparation)
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{
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bestEdge = edge;
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bestSeparation = s;
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}
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else
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{
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break;
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}
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}
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*edgeIndex = bestEdge;
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return bestSeparation;
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}
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static void FindIncidentEdge(ClipVertex c[2],
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const btBox2dShape* poly1, const btTransform& xf1, int edge1,
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const btBox2dShape* poly2, const btTransform& xf2)
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{
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const btVector3* normals1 = poly1->getNormals();
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int count2 = poly2->getVertexCount();
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const btVector3* vertices2 = poly2->getVertices();
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const btVector3* normals2 = poly2->getNormals();
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btAssert(0 <= edge1 && edge1 < poly1->getVertexCount());
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// Get the normal of the reference edge in poly2's frame.
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btVector3 normal1 = b2MulT(xf2.getBasis(), b2Mul(xf1.getBasis(), normals1[edge1]));
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// Find the incident edge on poly2.
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int index = 0;
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btScalar minDot = BT_LARGE_FLOAT;
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for (int i = 0; i < count2; ++i)
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{
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btScalar dot = b2Dot(normal1, normals2[i]);
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if (dot < minDot)
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{
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minDot = dot;
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index = i;
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}
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}
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// Build the clip vertices for the incident edge.
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int i1 = index;
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int i2 = i1 + 1 < count2 ? i1 + 1 : 0;
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c[0].v = b2Mul(xf2, vertices2[i1]);
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// c[0].id.features.referenceEdge = (unsigned char)edge1;
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// c[0].id.features.incidentEdge = (unsigned char)i1;
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// c[0].id.features.incidentVertex = 0;
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c[1].v = b2Mul(xf2, vertices2[i2]);
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// c[1].id.features.referenceEdge = (unsigned char)edge1;
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// c[1].id.features.incidentEdge = (unsigned char)i2;
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// c[1].id.features.incidentVertex = 1;
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}
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// Find edge normal of max separation on A - return if separating axis is found
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// Find edge normal of max separation on B - return if separation axis is found
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// Choose reference edge as min(minA, minB)
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// Find incident edge
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// Clip
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// The normal points from 1 to 2
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void b2CollidePolygons(btManifoldResult* manifold,
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const btBox2dShape* polyA, const btTransform& xfA,
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const btBox2dShape* polyB, const btTransform& xfB)
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{
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int edgeA = 0;
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btScalar separationA = FindMaxSeparation(&edgeA, polyA, xfA, polyB, xfB);
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if (separationA > 0.0f)
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return;
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int edgeB = 0;
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btScalar separationB = FindMaxSeparation(&edgeB, polyB, xfB, polyA, xfA);
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if (separationB > 0.0f)
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return;
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const btBox2dShape* poly1; // reference poly
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const btBox2dShape* poly2; // incident poly
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btTransform xf1, xf2;
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int edge1; // reference edge
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unsigned char flip;
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const btScalar k_relativeTol = 0.98f;
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const btScalar k_absoluteTol = 0.001f;
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// TODO_ERIN use "radius" of poly for absolute tolerance.
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if (separationB > k_relativeTol * separationA + k_absoluteTol)
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{
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poly1 = polyB;
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poly2 = polyA;
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xf1 = xfB;
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xf2 = xfA;
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edge1 = edgeB;
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flip = 1;
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}
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else
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{
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poly1 = polyA;
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poly2 = polyB;
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xf1 = xfA;
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xf2 = xfB;
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edge1 = edgeA;
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flip = 0;
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}
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ClipVertex incidentEdge[2];
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FindIncidentEdge(incidentEdge, poly1, xf1, edge1, poly2, xf2);
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int count1 = poly1->getVertexCount();
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const btVector3* vertices1 = poly1->getVertices();
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btVector3 v11 = vertices1[edge1];
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btVector3 v12 = edge1 + 1 < count1 ? vertices1[edge1+1] : vertices1[0];
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//btVector3 dv = v12 - v11;
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btVector3 sideNormal = b2Mul(xf1.getBasis(), v12 - v11);
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sideNormal.normalize();
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btVector3 frontNormal = btCrossS(sideNormal, 1.0f);
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v11 = b2Mul(xf1, v11);
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v12 = b2Mul(xf1, v12);
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btScalar frontOffset = b2Dot(frontNormal, v11);
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btScalar sideOffset1 = -b2Dot(sideNormal, v11);
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btScalar sideOffset2 = b2Dot(sideNormal, v12);
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// Clip incident edge against extruded edge1 side edges.
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ClipVertex clipPoints1[2];
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clipPoints1[0].v.setValue(0,0,0);
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clipPoints1[1].v.setValue(0,0,0);
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ClipVertex clipPoints2[2];
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clipPoints2[0].v.setValue(0,0,0);
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clipPoints2[1].v.setValue(0,0,0);
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int np;
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// Clip to box side 1
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np = ClipSegmentToLine(clipPoints1, incidentEdge, -sideNormal, sideOffset1);
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if (np < 2)
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return;
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// Clip to negative box side 1
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np = ClipSegmentToLine(clipPoints2, clipPoints1, sideNormal, sideOffset2);
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if (np < 2)
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{
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return;
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}
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// Now clipPoints2 contains the clipped points.
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btVector3 manifoldNormal = flip ? -frontNormal : frontNormal;
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int pointCount = 0;
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for (int i = 0; i < b2_maxManifoldPoints; ++i)
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{
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btScalar separation = b2Dot(frontNormal, clipPoints2[i].v) - frontOffset;
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if (separation <= 0.0f)
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{
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//b2ManifoldPoint* cp = manifold->points + pointCount;
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//btScalar separation = separation;
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//cp->localPoint1 = b2MulT(xfA, clipPoints2[i].v);
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//cp->localPoint2 = b2MulT(xfB, clipPoints2[i].v);
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manifold->addContactPoint(-manifoldNormal,clipPoints2[i].v,separation);
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// cp->id = clipPoints2[i].id;
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// cp->id.features.flip = flip;
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++pointCount;
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}
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}
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// manifold->pointCount = pointCount;}
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}
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