Use cylinder inertia tensor, instead of box, by default.

See Issue 427

Expose some internal data for constraints,
Thanks to Francois Sugny, see Issue 420

Demos/OpenGL/GL_DialogDynamicsWorld.cpp

@@ -229,7 +229,7 @@ GL_SliderControl* GL_DialogDynamicsWorld::createSlider(GL_DialogWindow* dialog,
 	int sliderX = dialog->getDialogHorPos() - m_screenWidth/2 + dialog->getDialogWidth()/2;
 //	int sliderY = dialog->getDialogVertPos() + m_screenHeight/2 + dialog->getDialogHeight()/2 + dialog->getNumControls()*20;
 	int sliderY = dialog->getDialogVertPos() - m_screenHeight/2 + dialog->getDialogHeight()/2 + dialog->getNumControls()*20;
-	trans.setOrigin(btVector3(sliderX, sliderY,-0.2f));
+	trans.setOrigin(btVector3((btScalar)sliderX, (btScalar)sliderY,(btScalar)-0.2f));
 	
 	body->setWorldTransform(trans);
 	//body->setDamping(0.999,0.99);
@@ -251,7 +251,7 @@ GL_SliderControl* GL_DialogDynamicsWorld::createSlider(GL_DialogWindow* dialog,
 	frameInA.setIdentity();
 	int offsX = -dialog->getDialogWidth()/2 + 16;
 	int offsY = -dialog->getDialogHeight()/2 + dialog->getNumControls()*20 + 36;
-	btVector3 offset(btVector3(offsX, offsY, 0.2f));
+	btVector3 offset(btVector3((btScalar)offsX, (btScalar)offsY, (btScalar)0.2f));
 	frameInA.setOrigin(offset);
 	
 	
@@ -309,7 +309,7 @@ GL_ToggleControl* GL_DialogDynamicsWorld::createToggle(GL_DialogWindow* dialog,
 	int toggleX = dialog->getDialogHorPos() - m_screenWidth/2 + dialog->getDialogWidth()/2;
 //	int toggleY = dialog->getDialogVertPos() + m_screenHeight/2 + dialog->getDialogHeight()/2 + dialog->getNumControls()*20;
 	int toggleY = dialog->getDialogVertPos() - m_screenHeight/2 + dialog->getDialogHeight()/2 + dialog->getNumControls()*20;
-	trans.setOrigin(btVector3(toggleX, toggleY, -0.2f));
+	trans.setOrigin(btVector3((btScalar)toggleX, (btScalar)toggleY,(btScalar) -0.2f));
 	
 	body->setWorldTransform(trans);
 	body->setDamping(0.999f,0.99f);

src/BulletCollision/CollisionShapes/btCylinderShape.cpp

@@ -47,7 +47,64 @@ void btCylinderShape::getAabb(const btTransform& t,btVector3& aabbMin,btVector3&
 
 void	btCylinderShape::calculateLocalInertia(btScalar mass,btVector3& inertia) const
 {
-	//approximation of box shape, todo: implement cylinder shape inertia before people notice ;-)
+
+//Until Bullet 2.77 a box approximation was used, so uncomment this if you need backwards compatibility
+//#define USE_BOX_INERTIA_APPROXIMATION 1
+#ifndef USE_BOX_INERTIA_APPROXIMATION
+
+	/*
+	cylinder is defined as following:
+	*
+	* - principle axis aligned along y by default, radius in x, z-value not used
+	* - for btCylinderShapeX: principle axis aligned along x, radius in y direction, z-value not used
+	* - for btCylinderShapeZ: principle axis aligned along z, radius in x direction, y-value not used
+	*
+	*/
+
+	btScalar radius2;	// square of cylinder radius
+	btScalar height2;	// square of cylinder height
+	btVector3 halfExtents = getHalfExtentsWithMargin();	// get cylinder dimension
+	btScalar div12 = mass / 12.f;
+	btScalar div4 = mass / 4.f;
+	btScalar div2 = mass / 2.f;
+	int idxRadius, idxHeight;
+
+	switch (m_upAxis)	// get indices of radius and height of cylinder
+	{
+		case 0:		// cylinder is aligned along x
+			idxRadius = 1;
+			idxHeight = 0;
+			break;
+		case 2:		// cylinder is aligned along z
+			idxRadius = 0;
+			idxHeight = 2;
+			break;
+		default:	// cylinder is aligned along y
+			idxRadius = 0;
+			idxHeight = 1;
+	}
+
+	// calculate squares
+	radius2 = halfExtents[idxRadius] * halfExtents[idxRadius];
+	height2 = btScalar(4.) * halfExtents[idxHeight] * halfExtents[idxHeight];
+
+	// calculate tensor terms
+	btScalar t1 = div12 * height2 + div4 * radius2;
+	btScalar t2 = div2 * radius2;
+
+	switch (m_upAxis)	// set diagonal elements of inertia tensor
+	{
+		case 0:		// cylinder is aligned along x
+			inertia.setValue(t2,t1,t1);
+			break;
+		case 2:		// cylinder is aligned along z
+			inertia.setValue(t1,t1,t2);
+			break;
+		default:	// cylinder is aligned along y
+			inertia.setValue(t1,t2,t1);
+	}
+#else //USE_BOX_INERTIA_APPROXIMATION
+	//approximation of box shape
 	btVector3 halfExtents = getHalfExtentsWithMargin();
 
 	btScalar lx=btScalar(2.)*(halfExtents.x());
@@ -57,7 +114,7 @@ void	btCylinderShape::calculateLocalInertia(btScalar mass,btVector3& inertia) co
 	inertia.setValue(mass/(btScalar(12.0)) * (ly*ly + lz*lz),
 					mass/(btScalar(12.0)) * (lx*lx + lz*lz),
 					mass/(btScalar(12.0)) * (lx*lx + ly*ly));
-
+#endif //USE_BOX_INERTIA_APPROXIMATION
 }
 
 

src/BulletDynamics/ConstraintSolver/btConeTwistConstraint.cpp

@@ -1114,4 +1114,12 @@ btScalar btConeTwistConstraint::getParam(int num, int axis) const
 }
 
 
+void btConeTwistConstraint::setFrames(const btTransform & frameA, const btTransform & frameB)
+{
+	m_rbAFrame = frameA;
+	m_rbBFrame = frameB;
+	buildJacobian();
+	//calculateTransforms();
+}
+
 

src/BulletDynamics/ConstraintSolver/btConeTwistConstraint.h

@@ -144,6 +144,16 @@ public:
 
 	void	updateRHS(btScalar	timeStep);
 
+	const btTransform & getFrameOffsetA() const
+	{
+		return m_rbAFrame;
+	}
+
+	const btTransform & getFrameOffsetB() const
+	{
+		return m_rbBFrame;
+	}
+
 	const btRigidBody& getRigidBodyA() const
 	{
 		return m_rbA;
@@ -244,6 +254,7 @@ public:
 	}
 	bool isPastSwingLimit() { return m_solveSwingLimit; }
 
+	void setFrames(const btTransform & frameA, const btTransform & frameB);
 
 	void setDamping(btScalar damping) { m_damping = damping; }
 

src/BulletDynamics/ConstraintSolver/btGeneric6DofConstraint.cpp

@@ -713,6 +713,15 @@ void	btGeneric6DofConstraint::updateRHS(btScalar	timeStep)
 }
 
 
+void btGeneric6DofConstraint::setFrames(const btTransform & frameA, const btTransform & frameB)
+{
+	m_frameInA = frameA;
+	m_frameInB = frameB;
+	buildJacobian();
+	calculateTransforms();
+}
+
+
 
 btVector3 btGeneric6DofConstraint::getAxis(int axis_index) const
 {

src/BulletDynamics/ConstraintSolver/btGeneric6DofConstraint.h

@@ -433,6 +433,7 @@ public:
 	*/
 	btScalar getRelativePivotPosition(int axis_index) const;
 
+	void setFrames(const btTransform & frameA, const btTransform & frameB);
 
 	//! Test angular limit.
 	/*!
@@ -446,23 +447,45 @@ public:
     	m_linearLimits.m_lowerLimit = linearLower;
     }
 
+	void	getLinearLowerLimit(btVector3& linearLower)
+	{
+		linearLower = m_linearLimits.m_lowerLimit;
+	}
+
     void	setLinearUpperLimit(const btVector3& linearUpper)
     {
     	m_linearLimits.m_upperLimit = linearUpper;
     }
 
+	void	getLinearUpperLimit(btVector3& linearUpper)
+	{
+		linearUpper = m_linearLimits.m_upperLimit;
+	}
+
     void	setAngularLowerLimit(const btVector3& angularLower)
     {
 		for(int i = 0; i < 3; i++) 
 			m_angularLimits[i].m_loLimit = btNormalizeAngle(angularLower[i]);
     }
 
+	void	getAngularLowerLimit(btVector3& angularLower)
+	{
+		for(int i = 0; i < 3; i++) 
+			angularLower[i] = m_angularLimits[i].m_loLimit;
+	}
+
     void	setAngularUpperLimit(const btVector3& angularUpper)
     {
 		for(int i = 0; i < 3; i++)
 			m_angularLimits[i].m_hiLimit = btNormalizeAngle(angularUpper[i]);
     }
 
+	void	getAngularUpperLimit(btVector3& angularUpper)
+	{
+		for(int i = 0; i < 3; i++)
+			angularUpper[i] = m_angularLimits[i].m_hiLimit;
+	}
+
 	//! Retrieves the angular limit informacion
     btRotationalLimitMotor * getRotationalLimitMotor(int index)
     {

src/BulletDynamics/ConstraintSolver/btHingeConstraint.cpp

@@ -550,8 +550,12 @@ void btHingeConstraint::getInfo2Internal(btConstraintInfo2* info, const btTransf
 }
 
 
-
+void btHingeConstraint::setFrames(const btTransform & frameA, const btTransform & frameB)
-
+{
+	m_rbAFrame = frameA;
+	m_rbBFrame = frameB;
+	buildJacobian();
+}
 
 
 void	btHingeConstraint::updateRHS(btScalar	timeStep)

src/BulletDynamics/ConstraintSolver/btHingeConstraint.h

@@ -134,6 +134,18 @@ public:
 		return m_rbB;	
 	}
 
+	btTransform & getFrameOffsetA()
+	{
+	return m_rbAFrame;
+	}
+
+	btTransform & getFrameOffsetB()
+	{
+		return m_rbBFrame;
+	}
+
+	void setFrames(const btTransform & frameA, const btTransform & frameB);
+	
 	void	setAngularOnly(bool angularOnly)
 	{
 		m_angularOnly = angularOnly;
@@ -182,8 +194,7 @@ public:
 		btVector3 rbAxisB1 =  quatRotate(rotationArc,rbAxisA1);
 		btVector3 rbAxisB2 = axisInB.cross(rbAxisB1);
 
-
+	m_rbBFrame.getOrigin() = m_rbB.getCenterOfMassTransform().inverse()(m_rbA.getCenterOfMassTransform()(pivotInA));
-		m_rbBFrame.getOrigin() = m_rbA.getCenterOfMassTransform()(pivotInA);
 		m_rbBFrame.getBasis().setValue( rbAxisB1.getX(),rbAxisB2.getX(),axisInB.getX(),
 										rbAxisB1.getY(),rbAxisB2.getY(),axisInB.getY(),
 										rbAxisB1.getZ(),rbAxisB2.getZ(),axisInB.getZ() );