add a btFixedConstraint with toggle between btGeneric6DofConsraint and btFixedConstraint in VoronoiFractureDemo

Demos/VoronoiFractureDemo/VoronoiFractureDemo.cpp

@@ -37,6 +37,8 @@ Voronoi fracture and shatter code and demo copyright (c) 2011 Alain Ducharme
 
 #include "GLDebugDrawer.h"
 static GLDebugDrawer sDebugDraw;
+static bool useGenericConstraint = false;
+
 
 void VoronoiFractureDemo::attachFixedConstraints()
 {
@@ -91,17 +93,29 @@ void VoronoiFractureDemo::attachFixedConstraints()
 
 						trA = body0->getWorldTransform().inverse()*globalFrame;
 						trB = body1->getWorldTransform().inverse()*globalFrame;
-
-						btGeneric6DofConstraint* dof6 = new btGeneric6DofConstraint(*body0,*body1,trA,trB,true);
-						dof6->setOverrideNumSolverIterations(100);
-
 						float totalMass = 1.f/body0->getInvMass() + 1.f/body1->getInvMass();
 
-						dof6->setBreakingImpulseThreshold(BREAKING_THRESHOLD*totalMass);
+						
+						if (useGenericConstraint)
+						{
+							btGeneric6DofConstraint* dof6 = new btGeneric6DofConstraint(*body0,*body1,trA,trB,true);
+							dof6->setOverrideNumSolverIterations(30);
 
-						for (int i=0;i<6;i++)
-							dof6->setLimit(i,0,0);
-						getDynamicsWorld()->addConstraint(dof6,true);
+
+							dof6->setBreakingImpulseThreshold(BREAKING_THRESHOLD*totalMass);
+
+							for (int i=0;i<6;i++)
+								dof6->setLimit(i,0,0);
+							getDynamicsWorld()->addConstraint(dof6,true);
+
+						} else
+						{
+							btFixedConstraint* fixed = new btFixedConstraint(*body0,*body1,trA,trB);
+							fixed->setBreakingImpulseThreshold(BREAKING_THRESHOLD*totalMass);
+							fixed ->setOverrideNumSolverIterations(30);
+							getDynamicsWorld()->addConstraint(fixed,true);
+
+						}
 							
 					}
 				}
@@ -509,6 +523,10 @@ void VoronoiFractureDemo::displayCallback(void) {
 
 void	VoronoiFractureDemo::initPhysics()
 {
+	useGenericConstraint = !useGenericConstraint;
+	printf("useGenericConstraint = %d\n", useGenericConstraint);
+
+	
 	setTexturing(true);
 	setShadows(true);
 
@@ -563,13 +581,33 @@ void	VoronoiFractureDemo::initPhysics()
 		m_dynamicsWorld->addRigidBody(body);
 	}
 
+	{
+		btCollisionShape* groundShape = new btBoxShape(btVector3(btScalar(10.),btScalar(8.),btScalar(1.)));
+		btScalar mass(0.);
+
+		//rigidbody is dynamic if and only if mass is non zero, otherwise static
+		bool isDynamic = (mass != 0.f);
+
+		btVector3 localInertia(0,0,0);
+		if (isDynamic)
+			groundShape->calculateLocalInertia(mass,localInertia);
+		groundTransform.setOrigin(btVector3(0,0,0));
+		//using motionstate is recommended, it provides interpolation capabilities, and only synchronizes 'active' objects
+		btDefaultMotionState* myMotionState = new btDefaultMotionState(groundTransform);
+		btRigidBody::btRigidBodyConstructionInfo rbInfo(mass,myMotionState,groundShape,localInertia);
+		btRigidBody* body = new btRigidBody(rbInfo);
+
+		//add the body to the dynamics world
+		m_dynamicsWorld->addRigidBody(body);
+	}
+
 	// ==> Voronoi Shatter Basic Demo: Random Cuboid
 
 	// Random size cuboid (defined by bounding box max and min)
-	btVector3 bbmax(btScalar(rand() / btScalar(RAND_MAX)) * 6. +0.5, btScalar(rand() / btScalar(RAND_MAX)) * 6. +0.5, btScalar(rand() / btScalar(RAND_MAX)) * 6. +0.5);
+	btVector3 bbmax(btScalar(rand() / btScalar(RAND_MAX)) * 12. +0.5, btScalar(rand() / btScalar(RAND_MAX)) * 1. +0.5, btScalar(rand() / btScalar(RAND_MAX)) * 1. +0.5);
 	btVector3 bbmin = -bbmax;
 	// Place it 10 units above ground
-	btVector3 bbt(0,10,0);
+	btVector3 bbt(0,15,0);
 	// Use an arbitrary material density for shards (should be consitent/relative with/to rest of RBs in world)
 	btScalar matDensity = 1;
 	// Using random rotation

src/BulletDynamics/CMakeLists.txt

@@ -6,6 +6,7 @@ SET(BulletDynamics_SRCS
 	Character/btKinematicCharacterController.cpp
 	ConstraintSolver/btConeTwistConstraint.cpp
 	ConstraintSolver/btContactConstraint.cpp
+	ConstraintSolver/btFixedConstraint.cpp
 	ConstraintSolver/btGearConstraint.cpp
 	ConstraintSolver/btGeneric6DofConstraint.cpp
 	ConstraintSolver/btGeneric6DofSpringConstraint.cpp
@@ -38,6 +39,7 @@ SET(ConstraintSolver_HDRS
 	ConstraintSolver/btConstraintSolver.h
 	ConstraintSolver/btContactConstraint.h
 	ConstraintSolver/btContactSolverInfo.h
+	ConstraintSolver/btFixedConstraint.h
 	ConstraintSolver/btGearConstraint.h
 	ConstraintSolver/btGeneric6DofConstraint.h
 	ConstraintSolver/btGeneric6DofSpringConstraint.h

src/BulletDynamics/ConstraintSolver/btFixedConstraint.cpp

@@ -0,0 +1,129 @@
+/*
+Bullet Continuous Collision Detection and Physics Library
+Copyright (c) 2013 Erwin Coumans  http://bulletphysics.org
+
+This software is provided 'as-is', without any express or implied warranty.
+In no event will the authors be held liable for any damages arising from the use of this software.
+Permission is granted to anyone to use this software for any purpose, 
+including commercial applications, and to alter it and redistribute it freely, 
+subject to the following restrictions:
+
+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.
+2. Altered source versions must be plainly marked as such, and must not be misrepresented as being the original software.
+3. This notice may not be removed or altered from any source distribution.
+*/
+
+
+#include "btFixedConstraint.h"
+#include "BulletDynamics/Dynamics/btRigidBody.h"
+#include "LinearMath/btTransformUtil.h"
+#include <new>
+
+
+btFixedConstraint::btFixedConstraint(btRigidBody& rbA,btRigidBody& rbB, const btTransform& frameInA,const btTransform& frameInB)
+:btTypedConstraint(FIXED_CONSTRAINT_TYPE,rbA,rbB)
+{
+	m_pivotInA = frameInA.getOrigin();
+	m_pivotInB = frameInB.getOrigin();
+	m_relTargetAB = frameInA.getRotation()*frameInB.getRotation().inverse();
+
+}
+
+btFixedConstraint::~btFixedConstraint ()
+{
+}
+
+	
+void btFixedConstraint::getInfo1 (btConstraintInfo1* info)
+{
+	info->m_numConstraintRows = 6;
+	info->nub = 6;
+}
+
+void btFixedConstraint::getInfo2 (btConstraintInfo2* info)
+{
+	//fix the 3 linear degrees of freedom
+
+	
+	const btVector3& worldPosA = m_rbA.getCenterOfMassTransform().getOrigin();
+	const btMatrix3x3& worldOrnA = m_rbA.getCenterOfMassTransform().getBasis();
+	const btVector3& worldPosB= m_rbB.getCenterOfMassTransform().getOrigin();
+	const btMatrix3x3& worldOrnB = m_rbB.getCenterOfMassTransform().getBasis();
+	
+
+	info->m_J1linearAxis[0] = 1;
+	info->m_J1linearAxis[info->rowskip+1] = 1;
+	info->m_J1linearAxis[2*info->rowskip+2] = 1;
+
+	btVector3 a1 = worldOrnA*m_pivotInA;
+	{
+		btVector3* angular0 = (btVector3*)(info->m_J1angularAxis);
+		btVector3* angular1 = (btVector3*)(info->m_J1angularAxis+info->rowskip);
+		btVector3* angular2 = (btVector3*)(info->m_J1angularAxis+2*info->rowskip);
+		btVector3 a1neg = -a1;
+		a1neg.getSkewSymmetricMatrix(angular0,angular1,angular2);
+	}
+    
+	if (info->m_J2linearAxis)
+	{
+		info->m_J2linearAxis[0] = -1;
+		info->m_J2linearAxis[info->rowskip+1] = -1;
+		info->m_J2linearAxis[2*info->rowskip+2] = -1;
+	}
+	
+	btVector3 a2 = worldOrnB*m_pivotInB;
+   
+	{
+	//	btVector3 a2n = -a2;
+		btVector3* angular0 = (btVector3*)(info->m_J2angularAxis);
+		btVector3* angular1 = (btVector3*)(info->m_J2angularAxis+info->rowskip);
+		btVector3* angular2 = (btVector3*)(info->m_J2angularAxis+2*info->rowskip);
+		a2.getSkewSymmetricMatrix(angular0,angular1,angular2);
+	}
+
+    // set right hand side for the linear dofs
+	btScalar k = info->fps * info->erp;
+	
+	btVector3 linearError = k*(a2+worldPosB-a1-worldPosA);
+    int j;
+	for (j=0; j<3; j++)
+    {
+
+
+
+        info->m_constraintError[j*info->rowskip] = linearError[j];
+		//printf("info->m_constraintError[%d]=%f\n",j,info->m_constraintError[j]);
+    }
+
+		//fix the 3 angular degrees of freedom
+
+	int start_row = 3;
+	int s = info->rowskip;
+    int start_index = start_row * s;
+
+    // 3 rows to make body rotations equal
+	info->m_J1angularAxis[start_index] = 1;
+    info->m_J1angularAxis[start_index + s + 1] = 1;
+    info->m_J1angularAxis[start_index + s*2+2] = 1;
+    if ( info->m_J2angularAxis)
+    {
+        info->m_J2angularAxis[start_index] = -1;
+        info->m_J2angularAxis[start_index + s+1] = -1;
+        info->m_J2angularAxis[start_index + s*2+2] = -1;
+    }
+
+    // set right hand side for the angular dofs
+
+	btVector3 diff;
+	btScalar angle;
+	btMatrix3x3 mrelCur = worldOrnA *worldOrnB.inverse();
+	btQuaternion qrelCur;
+	mrelCur.getRotation(qrelCur);
+	btTransformUtil::calculateDiffAxisAngleQuaternion(m_relTargetAB,qrelCur,diff,angle);
+	diff*=-angle;
+	for (j=0; j<3; j++)
+    {
+        info->m_constraintError[(3+j)*info->rowskip] = k * diff[j];
+    }
+
+}

src/BulletDynamics/ConstraintSolver/btFixedConstraint.h

@@ -0,0 +1,49 @@
+/*
+Bullet Continuous Collision Detection and Physics Library
+Copyright (c) 2013 Erwin Coumans  http://bulletphysics.org
+
+This software is provided 'as-is', without any express or implied warranty.
+In no event will the authors be held liable for any damages arising from the use of this software.
+Permission is granted to anyone to use this software for any purpose, 
+including commercial applications, and to alter it and redistribute it freely, 
+subject to the following restrictions:
+
+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.
+2. Altered source versions must be plainly marked as such, and must not be misrepresented as being the original software.
+3. This notice may not be removed or altered from any source distribution.
+*/
+
+#ifndef BT_FIXED_CONSTRAINT_H
+#define BT_FIXED_CONSTRAINT_H
+
+#include "btTypedConstraint.h"
+
+ATTRIBUTE_ALIGNED16(class) btFixedConstraint : public btTypedConstraint
+{
+	btVector3 m_pivotInA;
+	btVector3 m_pivotInB;
+	btQuaternion m_relTargetAB;
+
+public:
+	btFixedConstraint(btRigidBody& rbA,btRigidBody& rbB, const btTransform& frameInA,const btTransform& frameInB);
+	
+	virtual ~btFixedConstraint();
+
+	
+	virtual void getInfo1 (btConstraintInfo1* info);
+
+	virtual void getInfo2 (btConstraintInfo2* info);
+
+	virtual	void	setParam(int num, btScalar value, int axis = -1)
+	{
+		btAssert(0);
+	}
+	virtual	btScalar getParam(int num, int axis = -1) const
+	{
+		btAssert(0);
+		return 0.f;
+	}
+
+};
+
+#endif //BT_FIXED_CONSTRAINT_H

src/BulletDynamics/ConstraintSolver/btTypedConstraint.h

@@ -43,6 +43,7 @@ enum btTypedConstraintType
 	CONTACT_CONSTRAINT_TYPE,
 	D6_SPRING_CONSTRAINT_TYPE,
 	GEAR_CONSTRAINT_TYPE,
+	FIXED_CONSTRAINT_TYPE,
 	MAX_CONSTRAINT_TYPE
 };
 

src/Makefile.am

@@ -317,6 +317,7 @@ libBulletDynamics_la_SOURCES = \
 		BulletDynamics/Dynamics/btSimpleDynamicsWorld.cpp \
 		BulletDynamics/Dynamics/Bullet-C-API.cpp \
 		BulletDynamics/Dynamics/btDiscreteDynamicsWorld.cpp \
+		BulletDynamics/ConstraintSolver/btFixedConstraint.cpp \
 		BulletDynamics/ConstraintSolver/btGearConstraint.cpp \
 		BulletDynamics/ConstraintSolver/btGeneric6DofConstraint.cpp \
 		BulletDynamics/ConstraintSolver/btGeneric6DofSpringConstraint.cpp \

src/btBulletDynamicsCommon.h

@@ -33,6 +33,8 @@ subject to the following restrictions:
 #include "BulletDynamics/ConstraintSolver/btUniversalConstraint.h"
 #include "BulletDynamics/ConstraintSolver/btHinge2Constraint.h"
 #include "BulletDynamics/ConstraintSolver/btGearConstraint.h"
+#include "BulletDynamics/ConstraintSolver/btFixedConstraint.h"
+
 
 #include "BulletDynamics/ConstraintSolver/btSequentialImpulseConstraintSolver.h"