bullet: Streamline bundling, remove extraneous src/ folder

Document version and how to extract sources in thirdparty/README.md.
Drop unnecessary CMake and Premake files.
Simplify SCsub, drop unused one.

1 files changed, 1120 insertions, 0 deletions

diff --git a/thirdparty/bullet/BulletDynamics/ConstraintSolver/btHingeConstraint.cpp b/thirdparty/bullet/BulletDynamics/ConstraintSolver/btHingeConstraint.cpp
new file mode 100644
index 0000000000..7e5e6f9e54
--- /dev/null
+++ b/thirdparty/bullet/BulletDynamics/ConstraintSolver/btHingeConstraint.cpp
@@ -0,0 +1,1120 @@
+/*
+Bullet Continuous Collision Detection and Physics Library
+Copyright (c) 2003-2006 Erwin Coumans  http://continuousphysics.com/Bullet/
+
+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 "btHingeConstraint.h"
+#include "BulletDynamics/Dynamics/btRigidBody.h"
+#include "LinearMath/btTransformUtil.h"
+#include "LinearMath/btMinMax.h"
+#include <new>
+#include "btSolverBody.h"
+
+
+
+//#define HINGE_USE_OBSOLETE_SOLVER false
+#define HINGE_USE_OBSOLETE_SOLVER false
+
+#define HINGE_USE_FRAME_OFFSET true
+
+#ifndef __SPU__
+
+
+
+
+
+btHingeConstraint::btHingeConstraint(btRigidBody& rbA,btRigidBody& rbB, const btVector3& pivotInA,const btVector3& pivotInB,
+									 const btVector3& axisInA,const btVector3& axisInB, bool useReferenceFrameA)
+									 :btTypedConstraint(HINGE_CONSTRAINT_TYPE, rbA,rbB),
+#ifdef _BT_USE_CENTER_LIMIT_
+									 m_limit(),
+#endif
+									 m_angularOnly(false),
+									 m_enableAngularMotor(false),
+									 m_useSolveConstraintObsolete(HINGE_USE_OBSOLETE_SOLVER),
+									 m_useOffsetForConstraintFrame(HINGE_USE_FRAME_OFFSET),
+									 m_useReferenceFrameA(useReferenceFrameA),
+									 m_flags(0),
+									 m_normalCFM(0),
+									 m_normalERP(0),
+									 m_stopCFM(0),
+									 m_stopERP(0)
+{
+	m_rbAFrame.getOrigin() = pivotInA;
+	
+	// since no frame is given, assume this to be zero angle and just pick rb transform axis
+	btVector3 rbAxisA1 = rbA.getCenterOfMassTransform().getBasis().getColumn(0);
+
+	btVector3 rbAxisA2;
+	btScalar projection = axisInA.dot(rbAxisA1);
+	if (projection >= 1.0f - SIMD_EPSILON) {
+		rbAxisA1 = -rbA.getCenterOfMassTransform().getBasis().getColumn(2);
+		rbAxisA2 = rbA.getCenterOfMassTransform().getBasis().getColumn(1);
+	} else if (projection <= -1.0f + SIMD_EPSILON) {
+		rbAxisA1 = rbA.getCenterOfMassTransform().getBasis().getColumn(2);
+		rbAxisA2 = rbA.getCenterOfMassTransform().getBasis().getColumn(1);      
+	} else {
+		rbAxisA2 = axisInA.cross(rbAxisA1);
+		rbAxisA1 = rbAxisA2.cross(axisInA);
+	}
+
+	m_rbAFrame.getBasis().setValue( rbAxisA1.getX(),rbAxisA2.getX(),axisInA.getX(),
+									rbAxisA1.getY(),rbAxisA2.getY(),axisInA.getY(),
+									rbAxisA1.getZ(),rbAxisA2.getZ(),axisInA.getZ() );
+
+	btQuaternion rotationArc = shortestArcQuat(axisInA,axisInB);
+	btVector3 rbAxisB1 =  quatRotate(rotationArc,rbAxisA1);
+	btVector3 rbAxisB2 =  axisInB.cross(rbAxisB1);	
+	
+	m_rbBFrame.getOrigin() = pivotInB;
+	m_rbBFrame.getBasis().setValue( rbAxisB1.getX(),rbAxisB2.getX(),axisInB.getX(),
+									rbAxisB1.getY(),rbAxisB2.getY(),axisInB.getY(),
+									rbAxisB1.getZ(),rbAxisB2.getZ(),axisInB.getZ() );
+	
+#ifndef	_BT_USE_CENTER_LIMIT_
+	//start with free
+	m_lowerLimit = btScalar(1.0f);
+	m_upperLimit = btScalar(-1.0f);
+	m_biasFactor = 0.3f;
+	m_relaxationFactor = 1.0f;
+	m_limitSoftness = 0.9f;
+	m_solveLimit = false;
+#endif
+	m_referenceSign = m_useReferenceFrameA ? btScalar(-1.f) : btScalar(1.f);
+}
+
+
+
+btHingeConstraint::btHingeConstraint(btRigidBody& rbA,const btVector3& pivotInA,const btVector3& axisInA, bool useReferenceFrameA)
+:btTypedConstraint(HINGE_CONSTRAINT_TYPE, rbA),
+#ifdef _BT_USE_CENTER_LIMIT_
+m_limit(),
+#endif
+m_angularOnly(false), m_enableAngularMotor(false), 
+m_useSolveConstraintObsolete(HINGE_USE_OBSOLETE_SOLVER),
+m_useOffsetForConstraintFrame(HINGE_USE_FRAME_OFFSET),
+m_useReferenceFrameA(useReferenceFrameA),
+m_flags(0),
+m_normalCFM(0),
+m_normalERP(0),
+m_stopCFM(0),
+m_stopERP(0)
+{
+
+	// since no frame is given, assume this to be zero angle and just pick rb transform axis
+	// fixed axis in worldspace
+	btVector3 rbAxisA1, rbAxisA2;
+	btPlaneSpace1(axisInA, rbAxisA1, rbAxisA2);
+
+	m_rbAFrame.getOrigin() = pivotInA;
+	m_rbAFrame.getBasis().setValue( rbAxisA1.getX(),rbAxisA2.getX(),axisInA.getX(),
+									rbAxisA1.getY(),rbAxisA2.getY(),axisInA.getY(),
+									rbAxisA1.getZ(),rbAxisA2.getZ(),axisInA.getZ() );
+
+	btVector3 axisInB = rbA.getCenterOfMassTransform().getBasis() * axisInA;
+
+	btQuaternion rotationArc = shortestArcQuat(axisInA,axisInB);
+	btVector3 rbAxisB1 =  quatRotate(rotationArc,rbAxisA1);
+	btVector3 rbAxisB2 = axisInB.cross(rbAxisB1);
+
+
+	m_rbBFrame.getOrigin() = 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() );
+	
+#ifndef	_BT_USE_CENTER_LIMIT_
+	//start with free
+	m_lowerLimit = btScalar(1.0f);
+	m_upperLimit = btScalar(-1.0f);
+	m_biasFactor = 0.3f;
+	m_relaxationFactor = 1.0f;
+	m_limitSoftness = 0.9f;
+	m_solveLimit = false;
+#endif
+	m_referenceSign = m_useReferenceFrameA ? btScalar(-1.f) : btScalar(1.f);
+}
+
+
+
+btHingeConstraint::btHingeConstraint(btRigidBody& rbA,btRigidBody& rbB, 
+								     const btTransform& rbAFrame, const btTransform& rbBFrame, bool useReferenceFrameA)
+:btTypedConstraint(HINGE_CONSTRAINT_TYPE, rbA,rbB),m_rbAFrame(rbAFrame),m_rbBFrame(rbBFrame),
+#ifdef _BT_USE_CENTER_LIMIT_
+m_limit(),
+#endif
+m_angularOnly(false),
+m_enableAngularMotor(false),
+m_useSolveConstraintObsolete(HINGE_USE_OBSOLETE_SOLVER),
+m_useOffsetForConstraintFrame(HINGE_USE_FRAME_OFFSET),
+m_useReferenceFrameA(useReferenceFrameA),
+m_flags(0),
+m_normalCFM(0),
+m_normalERP(0),
+m_stopCFM(0),
+m_stopERP(0)
+{
+#ifndef	_BT_USE_CENTER_LIMIT_
+	//start with free
+	m_lowerLimit = btScalar(1.0f);
+	m_upperLimit = btScalar(-1.0f);
+	m_biasFactor = 0.3f;
+	m_relaxationFactor = 1.0f;
+	m_limitSoftness = 0.9f;
+	m_solveLimit = false;
+#endif
+	m_referenceSign = m_useReferenceFrameA ? btScalar(-1.f) : btScalar(1.f);
+}			
+
+
+
+btHingeConstraint::btHingeConstraint(btRigidBody& rbA, const btTransform& rbAFrame, bool useReferenceFrameA)
+:btTypedConstraint(HINGE_CONSTRAINT_TYPE, rbA),m_rbAFrame(rbAFrame),m_rbBFrame(rbAFrame),
+#ifdef _BT_USE_CENTER_LIMIT_
+m_limit(),
+#endif
+m_angularOnly(false),
+m_enableAngularMotor(false),
+m_useSolveConstraintObsolete(HINGE_USE_OBSOLETE_SOLVER),
+m_useOffsetForConstraintFrame(HINGE_USE_FRAME_OFFSET),
+m_useReferenceFrameA(useReferenceFrameA),
+m_flags(0),
+m_normalCFM(0),
+m_normalERP(0),
+m_stopCFM(0),
+m_stopERP(0)
+{
+	///not providing rigidbody B means implicitly using worldspace for body B
+
+	m_rbBFrame.getOrigin() = m_rbA.getCenterOfMassTransform()(m_rbAFrame.getOrigin());
+#ifndef	_BT_USE_CENTER_LIMIT_
+	//start with free
+	m_lowerLimit = btScalar(1.0f);
+	m_upperLimit = btScalar(-1.0f);
+	m_biasFactor = 0.3f;
+	m_relaxationFactor = 1.0f;
+	m_limitSoftness = 0.9f;
+	m_solveLimit = false;
+#endif
+	m_referenceSign = m_useReferenceFrameA ? btScalar(-1.f) : btScalar(1.f);
+}
+
+
+
+void	btHingeConstraint::buildJacobian()
+{
+	if (m_useSolveConstraintObsolete)
+	{
+		m_appliedImpulse = btScalar(0.);
+		m_accMotorImpulse = btScalar(0.);
+
+		if (!m_angularOnly)
+		{
+			btVector3 pivotAInW = m_rbA.getCenterOfMassTransform()*m_rbAFrame.getOrigin();
+			btVector3 pivotBInW = m_rbB.getCenterOfMassTransform()*m_rbBFrame.getOrigin();
+			btVector3 relPos = pivotBInW - pivotAInW;
+
+			btVector3 normal[3];
+			if (relPos.length2() > SIMD_EPSILON)
+			{
+				normal[0] = relPos.normalized();
+			}
+			else
+			{
+				normal[0].setValue(btScalar(1.0),0,0);
+			}
+
+			btPlaneSpace1(normal[0], normal[1], normal[2]);
+
+			for (int i=0;i<3;i++)
+			{
+				new (&m_jac[i]) btJacobianEntry(
+				m_rbA.getCenterOfMassTransform().getBasis().transpose(),
+				m_rbB.getCenterOfMassTransform().getBasis().transpose(),
+				pivotAInW - m_rbA.getCenterOfMassPosition(),
+				pivotBInW - m_rbB.getCenterOfMassPosition(),
+				normal[i],
+				m_rbA.getInvInertiaDiagLocal(),
+				m_rbA.getInvMass(),
+				m_rbB.getInvInertiaDiagLocal(),
+				m_rbB.getInvMass());
+			}
+		}
+
+		//calculate two perpendicular jointAxis, orthogonal to hingeAxis
+		//these two jointAxis require equal angular velocities for both bodies
+
+		//this is unused for now, it's a todo
+		btVector3 jointAxis0local;
+		btVector3 jointAxis1local;
+		
+		btPlaneSpace1(m_rbAFrame.getBasis().getColumn(2),jointAxis0local,jointAxis1local);
+
+		btVector3 jointAxis0 = getRigidBodyA().getCenterOfMassTransform().getBasis() * jointAxis0local;
+		btVector3 jointAxis1 = getRigidBodyA().getCenterOfMassTransform().getBasis() * jointAxis1local;
+		btVector3 hingeAxisWorld = getRigidBodyA().getCenterOfMassTransform().getBasis() * m_rbAFrame.getBasis().getColumn(2);
+			
+		new (&m_jacAng[0])	btJacobianEntry(jointAxis0,
+			m_rbA.getCenterOfMassTransform().getBasis().transpose(),
+			m_rbB.getCenterOfMassTransform().getBasis().transpose(),
+			m_rbA.getInvInertiaDiagLocal(),
+			m_rbB.getInvInertiaDiagLocal());
+
+		new (&m_jacAng[1])	btJacobianEntry(jointAxis1,
+			m_rbA.getCenterOfMassTransform().getBasis().transpose(),
+			m_rbB.getCenterOfMassTransform().getBasis().transpose(),
+			m_rbA.getInvInertiaDiagLocal(),
+			m_rbB.getInvInertiaDiagLocal());
+
+		new (&m_jacAng[2])	btJacobianEntry(hingeAxisWorld,
+			m_rbA.getCenterOfMassTransform().getBasis().transpose(),
+			m_rbB.getCenterOfMassTransform().getBasis().transpose(),
+			m_rbA.getInvInertiaDiagLocal(),
+			m_rbB.getInvInertiaDiagLocal());
+
+			// clear accumulator
+			m_accLimitImpulse = btScalar(0.);
+
+			// test angular limit
+			testLimit(m_rbA.getCenterOfMassTransform(),m_rbB.getCenterOfMassTransform());
+
+		//Compute K = J*W*J' for hinge axis
+		btVector3 axisA =  getRigidBodyA().getCenterOfMassTransform().getBasis() *  m_rbAFrame.getBasis().getColumn(2);
+		m_kHinge =   1.0f / (getRigidBodyA().computeAngularImpulseDenominator(axisA) +
+							 getRigidBodyB().computeAngularImpulseDenominator(axisA));
+
+	}
+}
+
+
+#endif //__SPU__
+
+
+static inline btScalar btNormalizeAnglePositive(btScalar angle)
+{
+  return btFmod(btFmod(angle, btScalar(2.0*SIMD_PI)) + btScalar(2.0*SIMD_PI), btScalar(2.0*SIMD_PI));
+}
+
+
+
+static btScalar btShortestAngularDistance(btScalar accAngle, btScalar curAngle)
+{
+	btScalar result = btNormalizeAngle(btNormalizeAnglePositive(btNormalizeAnglePositive(curAngle) -
+	btNormalizeAnglePositive(accAngle)));
+	return result;
+}
+
+static btScalar btShortestAngleUpdate(btScalar accAngle, btScalar curAngle)
+{
+	btScalar tol(0.3);
+	btScalar result = btShortestAngularDistance(accAngle, curAngle);
+
+	  if (btFabs(result) > tol)
+		return curAngle;
+	  else
+		return accAngle + result;
+
+	return curAngle;
+}
+
+
+btScalar btHingeAccumulatedAngleConstraint::getAccumulatedHingeAngle()
+{
+	btScalar hingeAngle = getHingeAngle();
+	m_accumulatedAngle = btShortestAngleUpdate(m_accumulatedAngle,hingeAngle);
+	return m_accumulatedAngle;
+}
+void	btHingeAccumulatedAngleConstraint::setAccumulatedHingeAngle(btScalar accAngle)
+{
+	m_accumulatedAngle  = accAngle;
+}
+
+void btHingeAccumulatedAngleConstraint::getInfo1(btConstraintInfo1* info)
+{
+	//update m_accumulatedAngle
+	btScalar curHingeAngle = getHingeAngle();
+	m_accumulatedAngle = btShortestAngleUpdate(m_accumulatedAngle,curHingeAngle);
+
+	btHingeConstraint::getInfo1(info);
+	
+}
+
+
+void btHingeConstraint::getInfo1(btConstraintInfo1* info)
+{
+
+
+	if (m_useSolveConstraintObsolete)
+	{
+		info->m_numConstraintRows = 0;
+		info->nub = 0;
+	}
+	else
+	{
+		info->m_numConstraintRows = 5; // Fixed 3 linear + 2 angular
+		info->nub = 1; 
+		//always add the row, to avoid computation (data is not available yet)
+		//prepare constraint
+		testLimit(m_rbA.getCenterOfMassTransform(),m_rbB.getCenterOfMassTransform());
+		if(getSolveLimit() || getEnableAngularMotor())
+		{
+			info->m_numConstraintRows++; // limit 3rd anguar as well
+			info->nub--; 
+		}
+
+	}
+}
+
+void btHingeConstraint::getInfo1NonVirtual(btConstraintInfo1* info)
+{
+	if (m_useSolveConstraintObsolete)
+	{
+		info->m_numConstraintRows = 0;
+		info->nub = 0;
+	}
+	else
+	{
+		//always add the 'limit' row, to avoid computation (data is not available yet)
+		info->m_numConstraintRows = 6; // Fixed 3 linear + 2 angular
+		info->nub = 0; 
+	}
+}
+
+void btHingeConstraint::getInfo2 (btConstraintInfo2* info)
+{
+	if(m_useOffsetForConstraintFrame)
+	{
+		getInfo2InternalUsingFrameOffset(info, m_rbA.getCenterOfMassTransform(),m_rbB.getCenterOfMassTransform(),m_rbA.getAngularVelocity(),m_rbB.getAngularVelocity());
+	}
+	else
+	{
+		getInfo2Internal(info, m_rbA.getCenterOfMassTransform(),m_rbB.getCenterOfMassTransform(),m_rbA.getAngularVelocity(),m_rbB.getAngularVelocity());
+	}
+}
+
+
+void	btHingeConstraint::getInfo2NonVirtual (btConstraintInfo2* info,const btTransform& transA,const btTransform& transB,const btVector3& angVelA,const btVector3& angVelB)
+{
+	///the regular (virtual) implementation getInfo2 already performs 'testLimit' during getInfo1, so we need to do it now
+	testLimit(transA,transB);
+
+	getInfo2Internal(info,transA,transB,angVelA,angVelB);
+}
+
+
+void btHingeConstraint::getInfo2Internal(btConstraintInfo2* info, const btTransform& transA,const btTransform& transB,const btVector3& angVelA,const btVector3& angVelB)
+{
+
+	btAssert(!m_useSolveConstraintObsolete);
+	int i, skip = info->rowskip;
+	// transforms in world space
+	btTransform trA = transA*m_rbAFrame;
+	btTransform trB = transB*m_rbBFrame;
+	// pivot point
+	btVector3 pivotAInW = trA.getOrigin();
+	btVector3 pivotBInW = trB.getOrigin();
+#if 0
+	if (0)
+	{
+		for (i=0;i<6;i++)
+		{
+			info->m_J1linearAxis[i*skip]=0;
+			info->m_J1linearAxis[i*skip+1]=0;
+			info->m_J1linearAxis[i*skip+2]=0;
+
+			info->m_J1angularAxis[i*skip]=0;
+			info->m_J1angularAxis[i*skip+1]=0;
+			info->m_J1angularAxis[i*skip+2]=0;
+
+			info->m_J2linearAxis[i*skip]=0;
+			info->m_J2linearAxis[i*skip+1]=0;
+			info->m_J2linearAxis[i*skip+2]=0;
+
+			info->m_J2angularAxis[i*skip]=0;
+			info->m_J2angularAxis[i*skip+1]=0;
+			info->m_J2angularAxis[i*skip+2]=0;
+
+			info->m_constraintError[i*skip]=0.f;
+		}
+	}
+#endif //#if 0
+	// linear (all fixed)
+
+	if (!m_angularOnly)
+	{
+		info->m_J1linearAxis[0] = 1;
+		info->m_J1linearAxis[skip + 1] = 1;
+		info->m_J1linearAxis[2 * skip + 2] = 1;
+
+		info->m_J2linearAxis[0] = -1;
+		info->m_J2linearAxis[skip + 1] = -1;
+		info->m_J2linearAxis[2 * skip + 2] = -1;
+	}	
+
+
+
+
+	btVector3 a1 = pivotAInW - transA.getOrigin();
+	{
+		btVector3* angular0 = (btVector3*)(info->m_J1angularAxis);
+		btVector3* angular1 = (btVector3*)(info->m_J1angularAxis + skip);
+		btVector3* angular2 = (btVector3*)(info->m_J1angularAxis + 2 * skip);
+		btVector3 a1neg = -a1;
+		a1neg.getSkewSymmetricMatrix(angular0,angular1,angular2);
+	}
+	btVector3 a2 = pivotBInW - transB.getOrigin();
+	{
+		btVector3* angular0 = (btVector3*)(info->m_J2angularAxis);
+		btVector3* angular1 = (btVector3*)(info->m_J2angularAxis + skip);
+		btVector3* angular2 = (btVector3*)(info->m_J2angularAxis + 2 * skip);
+		a2.getSkewSymmetricMatrix(angular0,angular1,angular2);
+	}
+	// linear RHS
+	btScalar normalErp = (m_flags & BT_HINGE_FLAGS_ERP_NORM) ? m_normalERP : info->erp;
+
+    btScalar k = info->fps * normalErp;
+	if (!m_angularOnly)
+	{
+		for(i = 0; i < 3; i++)
+		{
+			info->m_constraintError[i * skip] = k * (pivotBInW[i] - pivotAInW[i]);
+		}
+	}
+	// make rotations around X and Y equal
+	// the hinge axis should be the only unconstrained
+	// rotational axis, the angular velocity of the two bodies perpendicular to
+	// the hinge axis should be equal. thus the constraint equations are
+	//    p*w1 - p*w2 = 0
+	//    q*w1 - q*w2 = 0
+	// where p and q are unit vectors normal to the hinge axis, and w1 and w2
+	// are the angular velocity vectors of the two bodies.
+	// get hinge axis (Z)
+	btVector3 ax1 = trA.getBasis().getColumn(2);
+	// get 2 orthos to hinge axis (X, Y)
+	btVector3 p = trA.getBasis().getColumn(0);
+	btVector3 q = trA.getBasis().getColumn(1);
+	// set the two hinge angular rows 
+    int s3 = 3 * info->rowskip;
+    int s4 = 4 * info->rowskip;
+
+	info->m_J1angularAxis[s3 + 0] = p[0];
+	info->m_J1angularAxis[s3 + 1] = p[1];
+	info->m_J1angularAxis[s3 + 2] = p[2];
+	info->m_J1angularAxis[s4 + 0] = q[0];
+	info->m_J1angularAxis[s4 + 1] = q[1];
+	info->m_J1angularAxis[s4 + 2] = q[2];
+
+	info->m_J2angularAxis[s3 + 0] = -p[0];
+	info->m_J2angularAxis[s3 + 1] = -p[1];
+	info->m_J2angularAxis[s3 + 2] = -p[2];
+	info->m_J2angularAxis[s4 + 0] = -q[0];
+	info->m_J2angularAxis[s4 + 1] = -q[1];
+	info->m_J2angularAxis[s4 + 2] = -q[2];
+    // compute the right hand side of the constraint equation. set relative
+    // body velocities along p and q to bring the hinge back into alignment.
+    // if ax1,ax2 are the unit length hinge axes as computed from body1 and
+    // body2, we need to rotate both bodies along the axis u = (ax1 x ax2).
+    // if `theta' is the angle between ax1 and ax2, we need an angular velocity
+    // along u to cover angle erp*theta in one step :
+    //   |angular_velocity| = angle/time = erp*theta / stepsize
+    //                      = (erp*fps) * theta
+    //    angular_velocity  = |angular_velocity| * (ax1 x ax2) / |ax1 x ax2|
+    //                      = (erp*fps) * theta * (ax1 x ax2) / sin(theta)
+    // ...as ax1 and ax2 are unit length. if theta is smallish,
+    // theta ~= sin(theta), so
+    //    angular_velocity  = (erp*fps) * (ax1 x ax2)
+    // ax1 x ax2 is in the plane space of ax1, so we project the angular
+    // velocity to p and q to find the right hand side.
+    btVector3 ax2 = trB.getBasis().getColumn(2);
+	btVector3 u = ax1.cross(ax2);
+	info->m_constraintError[s3] = k * u.dot(p);
+	info->m_constraintError[s4] = k * u.dot(q);
+	// check angular limits
+	int nrow = 4; // last filled row
+	int srow;
+	btScalar limit_err = btScalar(0.0);
+	int limit = 0;
+	if(getSolveLimit())
+	{
+#ifdef	_BT_USE_CENTER_LIMIT_
+	limit_err = m_limit.getCorrection() * m_referenceSign;
+#else
+	limit_err = m_correction * m_referenceSign;
+#endif
+	limit = (limit_err > btScalar(0.0)) ? 1 : 2;
+
+	}
+	// if the hinge has joint limits or motor, add in the extra row
+	bool powered = getEnableAngularMotor();
+	if(limit || powered)
+	{
+		nrow++;
+		srow = nrow * info->rowskip;
+		info->m_J1angularAxis[srow+0] = ax1[0];
+		info->m_J1angularAxis[srow+1] = ax1[1];
+		info->m_J1angularAxis[srow+2] = ax1[2];
+
+		info->m_J2angularAxis[srow+0] = -ax1[0];
+		info->m_J2angularAxis[srow+1] = -ax1[1];
+		info->m_J2angularAxis[srow+2] = -ax1[2];
+
+		btScalar lostop = getLowerLimit();
+		btScalar histop = getUpperLimit();
+		if(limit && (lostop == histop))
+		{  // the joint motor is ineffective
+			powered = false;
+		}
+		info->m_constraintError[srow] = btScalar(0.0f);
+		btScalar currERP = (m_flags & BT_HINGE_FLAGS_ERP_STOP) ? m_stopERP : normalErp;
+		if(powered)
+		{
+			if(m_flags & BT_HINGE_FLAGS_CFM_NORM)
+			{
+				info->cfm[srow] = m_normalCFM;
+			}
+			btScalar mot_fact = getMotorFactor(m_hingeAngle, lostop, histop, m_motorTargetVelocity, info->fps * currERP);
+			info->m_constraintError[srow] += mot_fact * m_motorTargetVelocity * m_referenceSign;
+			info->m_lowerLimit[srow] = - m_maxMotorImpulse;
+			info->m_upperLimit[srow] =   m_maxMotorImpulse;
+		}
+		if(limit)
+		{
+			k = info->fps * currERP;
+			info->m_constraintError[srow] += k * limit_err;
+			if(m_flags & BT_HINGE_FLAGS_CFM_STOP)
+			{
+				info->cfm[srow] = m_stopCFM;
+			}
+			if(lostop == histop) 
+			{
+				// limited low and high simultaneously
+				info->m_lowerLimit[srow] = -SIMD_INFINITY;
+				info->m_upperLimit[srow] = SIMD_INFINITY;
+			}
+			else if(limit == 1) 
+			{ // low limit
+				info->m_lowerLimit[srow] = 0;
+				info->m_upperLimit[srow] = SIMD_INFINITY;
+			}
+			else 
+			{ // high limit
+				info->m_lowerLimit[srow] = -SIMD_INFINITY;
+				info->m_upperLimit[srow] = 0;
+			}
+			// bounce (we'll use slider parameter abs(1.0 - m_dampingLimAng) for that)
+#ifdef	_BT_USE_CENTER_LIMIT_
+			btScalar bounce = m_limit.getRelaxationFactor();
+#else
+			btScalar bounce = m_relaxationFactor;
+#endif
+			if(bounce > btScalar(0.0))
+			{
+				btScalar vel = angVelA.dot(ax1);
+				vel -= angVelB.dot(ax1);
+				// only apply bounce if the velocity is incoming, and if the
+				// resulting c[] exceeds what we already have.
+				if(limit == 1)
+				{	// low limit
+					if(vel < 0)
+					{
+						btScalar newc = -bounce * vel;
+						if(newc > info->m_constraintError[srow])
+						{
+							info->m_constraintError[srow] = newc;
+						}
+					}
+				}
+				else
+				{	// high limit - all those computations are reversed
+					if(vel > 0)
+					{
+						btScalar newc = -bounce * vel;
+						if(newc < info->m_constraintError[srow])
+						{
+							info->m_constraintError[srow] = newc;
+						}
+					}
+				}
+			}
+#ifdef	_BT_USE_CENTER_LIMIT_
+			info->m_constraintError[srow] *= m_limit.getBiasFactor();
+#else
+			info->m_constraintError[srow] *= m_biasFactor;
+#endif
+		} // if(limit)
+	} // if angular limit or powered
+}
+
+
+void btHingeConstraint::setFrames(const btTransform & frameA, const btTransform & frameB)
+{
+	m_rbAFrame = frameA;
+	m_rbBFrame = frameB;
+	buildJacobian();
+}
+
+
+void	btHingeConstraint::updateRHS(btScalar	timeStep)
+{
+	(void)timeStep;
+
+}
+
+
+
+
+btScalar btHingeConstraint::getHingeAngle()
+{
+	return getHingeAngle(m_rbA.getCenterOfMassTransform(),m_rbB.getCenterOfMassTransform());
+}
+
+btScalar btHingeConstraint::getHingeAngle(const btTransform& transA,const btTransform& transB)
+{
+	const btVector3 refAxis0  = transA.getBasis() * m_rbAFrame.getBasis().getColumn(0);
+	const btVector3 refAxis1  = transA.getBasis() * m_rbAFrame.getBasis().getColumn(1);
+	const btVector3 swingAxis = transB.getBasis() * m_rbBFrame.getBasis().getColumn(1);
+//	btScalar angle = btAtan2Fast(swingAxis.dot(refAxis0), swingAxis.dot(refAxis1));
+	btScalar angle = btAtan2(swingAxis.dot(refAxis0), swingAxis.dot(refAxis1));
+	return m_referenceSign * angle;
+}
+
+
+
+void btHingeConstraint::testLimit(const btTransform& transA,const btTransform& transB)
+{
+	// Compute limit information
+	m_hingeAngle = getHingeAngle(transA,transB);
+#ifdef	_BT_USE_CENTER_LIMIT_
+	m_limit.test(m_hingeAngle);
+#else
+	m_correction = btScalar(0.);
+	m_limitSign = btScalar(0.);
+	m_solveLimit = false;
+	if (m_lowerLimit <= m_upperLimit)
+	{
+		m_hingeAngle = btAdjustAngleToLimits(m_hingeAngle, m_lowerLimit, m_upperLimit);
+		if (m_hingeAngle <= m_lowerLimit)
+		{
+			m_correction = (m_lowerLimit - m_hingeAngle);
+			m_limitSign = 1.0f;
+			m_solveLimit = true;
+		} 
+		else if (m_hingeAngle >= m_upperLimit)
+		{
+			m_correction = m_upperLimit - m_hingeAngle;
+			m_limitSign = -1.0f;
+			m_solveLimit = true;
+		}
+	}
+#endif
+	return;
+}
+
+
+static btVector3 vHinge(0, 0, btScalar(1));
+
+void btHingeConstraint::setMotorTarget(const btQuaternion& qAinB, btScalar dt)
+{
+	// convert target from body to constraint space
+	btQuaternion qConstraint = m_rbBFrame.getRotation().inverse() * qAinB * m_rbAFrame.getRotation();
+	qConstraint.normalize();
+
+	// extract "pure" hinge component
+	btVector3 vNoHinge = quatRotate(qConstraint, vHinge); vNoHinge.normalize();
+	btQuaternion qNoHinge = shortestArcQuat(vHinge, vNoHinge);
+	btQuaternion qHinge = qNoHinge.inverse() * qConstraint;
+	qHinge.normalize();
+
+	// compute angular target, clamped to limits
+	btScalar targetAngle = qHinge.getAngle();
+	if (targetAngle > SIMD_PI) // long way around. flip quat and recalculate.
+	{
+		qHinge = -(qHinge);
+		targetAngle = qHinge.getAngle();
+	}
+	if (qHinge.getZ() < 0)
+		targetAngle = -targetAngle;
+
+	setMotorTarget(targetAngle, dt);
+}
+
+void btHingeConstraint::setMotorTarget(btScalar targetAngle, btScalar dt)
+{
+#ifdef	_BT_USE_CENTER_LIMIT_
+	m_limit.fit(targetAngle);
+#else
+	if (m_lowerLimit < m_upperLimit)
+	{
+		if (targetAngle < m_lowerLimit)
+			targetAngle = m_lowerLimit;
+		else if (targetAngle > m_upperLimit)
+			targetAngle = m_upperLimit;
+	}
+#endif
+	// compute angular velocity
+	btScalar curAngle  = getHingeAngle(m_rbA.getCenterOfMassTransform(),m_rbB.getCenterOfMassTransform());
+	btScalar dAngle = targetAngle - curAngle;
+	m_motorTargetVelocity = dAngle / dt;
+}
+
+
+
+void btHingeConstraint::getInfo2InternalUsingFrameOffset(btConstraintInfo2* info, const btTransform& transA,const btTransform& transB,const btVector3& angVelA,const btVector3& angVelB)
+{
+	btAssert(!m_useSolveConstraintObsolete);
+	int i, s = info->rowskip;
+	// transforms in world space
+	btTransform trA = transA*m_rbAFrame;
+	btTransform trB = transB*m_rbBFrame;
+	// pivot point
+//	btVector3 pivotAInW = trA.getOrigin();
+//	btVector3 pivotBInW = trB.getOrigin();
+#if 1
+	// difference between frames in WCS
+	btVector3 ofs = trB.getOrigin() - trA.getOrigin();
+	// now get weight factors depending on masses
+	btScalar miA = getRigidBodyA().getInvMass();
+	btScalar miB = getRigidBodyB().getInvMass();
+	bool hasStaticBody = (miA < SIMD_EPSILON) || (miB < SIMD_EPSILON);
+	btScalar miS = miA + miB;
+	btScalar factA, factB;
+	if(miS > btScalar(0.f))
+	{
+		factA = miB / miS;
+	}
+	else 
+	{
+		factA = btScalar(0.5f);
+	}
+	factB = btScalar(1.0f) - factA;
+	// get the desired direction of hinge axis
+	// as weighted sum of Z-orthos of frameA and frameB in WCS
+	btVector3 ax1A = trA.getBasis().getColumn(2);
+	btVector3 ax1B = trB.getBasis().getColumn(2);
+	btVector3 ax1 = ax1A * factA + ax1B * factB;
+	ax1.normalize();
+	// fill first 3 rows 
+	// we want: velA + wA x relA == velB + wB x relB
+	btTransform bodyA_trans = transA;
+	btTransform bodyB_trans = transB;
+	int s0 = 0;
+	int s1 = s;
+	int s2 = s * 2;
+	int nrow = 2; // last filled row
+	btVector3 tmpA, tmpB, relA, relB, p, q;
+	// get vector from bodyB to frameB in WCS
+	relB = trB.getOrigin() - bodyB_trans.getOrigin();
+	// get its projection to hinge axis
+	btVector3 projB = ax1 * relB.dot(ax1);
+	// get vector directed from bodyB to hinge axis (and orthogonal to it)
+	btVector3 orthoB = relB - projB;
+	// same for bodyA
+	relA = trA.getOrigin() - bodyA_trans.getOrigin();
+	btVector3 projA = ax1 * relA.dot(ax1);
+	btVector3 orthoA = relA - projA;
+	btVector3 totalDist = projA - projB;
+	// get offset vectors relA and relB
+	relA = orthoA + totalDist * factA;
+	relB = orthoB - totalDist * factB;
+	// now choose average ortho to hinge axis
+	p = orthoB * factA + orthoA * factB;
+	btScalar len2 = p.length2();
+	if(len2 > SIMD_EPSILON)
+	{
+		p /= btSqrt(len2);
+	}
+	else
+	{
+		p = trA.getBasis().getColumn(1);
+	}
+	// make one more ortho
+	q = ax1.cross(p);
+	// fill three rows
+	tmpA = relA.cross(p);
+	tmpB = relB.cross(p);
+    for (i=0; i<3; i++) info->m_J1angularAxis[s0+i] = tmpA[i];
+    for (i=0; i<3; i++) info->m_J2angularAxis[s0+i] = -tmpB[i];
+	tmpA = relA.cross(q);
+	tmpB = relB.cross(q);
+	if(hasStaticBody && getSolveLimit())
+	{ // to make constraint between static and dynamic objects more rigid
+		// remove wA (or wB) from equation if angular limit is hit
+		tmpB *= factB;
+		tmpA *= factA;
+	}
+	for (i=0; i<3; i++) info->m_J1angularAxis[s1+i] = tmpA[i];
+    for (i=0; i<3; i++) info->m_J2angularAxis[s1+i] = -tmpB[i];
+	tmpA = relA.cross(ax1);
+	tmpB = relB.cross(ax1);
+	if(hasStaticBody)
+	{ // to make constraint between static and dynamic objects more rigid
+		// remove wA (or wB) from equation
+		tmpB *= factB;
+		tmpA *= factA;
+	}
+	for (i=0; i<3; i++) info->m_J1angularAxis[s2+i] = tmpA[i];
+    for (i=0; i<3; i++) info->m_J2angularAxis[s2+i] = -tmpB[i];
+
+	btScalar normalErp = (m_flags & BT_HINGE_FLAGS_ERP_NORM)? m_normalERP : info->erp;
+	btScalar k = info->fps * normalErp;
+
+	if (!m_angularOnly)
+	{
+		for (i=0; i<3; i++) info->m_J1linearAxis[s0+i] = p[i];
+		for (i=0; i<3; i++) info->m_J1linearAxis[s1+i] = q[i];
+		for (i=0; i<3; i++) info->m_J1linearAxis[s2+i] = ax1[i];
+
+		for (i=0; i<3; i++) info->m_J2linearAxis[s0+i] = -p[i];
+		for (i=0; i<3; i++) info->m_J2linearAxis[s1+i] = -q[i];
+		for (i=0; i<3; i++) info->m_J2linearAxis[s2+i] = -ax1[i];
+
+	// compute three elements of right hand side
+	
+		btScalar rhs = k * p.dot(ofs);
+		info->m_constraintError[s0] = rhs;
+		rhs = k * q.dot(ofs);
+		info->m_constraintError[s1] = rhs;
+		rhs = k * ax1.dot(ofs);
+		info->m_constraintError[s2] = rhs;
+	}
+	// the hinge axis should be the only unconstrained
+	// rotational axis, the angular velocity of the two bodies perpendicular to
+	// the hinge axis should be equal. thus the constraint equations are
+	//    p*w1 - p*w2 = 0
+	//    q*w1 - q*w2 = 0
+	// where p and q are unit vectors normal to the hinge axis, and w1 and w2
+	// are the angular velocity vectors of the two bodies.
+	int s3 = 3 * s;
+	int s4 = 4 * s;
+	info->m_J1angularAxis[s3 + 0] = p[0];
+	info->m_J1angularAxis[s3 + 1] = p[1];
+	info->m_J1angularAxis[s3 + 2] = p[2];
+	info->m_J1angularAxis[s4 + 0] = q[0];
+	info->m_J1angularAxis[s4 + 1] = q[1];
+	info->m_J1angularAxis[s4 + 2] = q[2];
+
+	info->m_J2angularAxis[s3 + 0] = -p[0];
+	info->m_J2angularAxis[s3 + 1] = -p[1];
+	info->m_J2angularAxis[s3 + 2] = -p[2];
+	info->m_J2angularAxis[s4 + 0] = -q[0];
+	info->m_J2angularAxis[s4 + 1] = -q[1];
+	info->m_J2angularAxis[s4 + 2] = -q[2];
+	// compute the right hand side of the constraint equation. set relative
+	// body velocities along p and q to bring the hinge back into alignment.
+	// if ax1A,ax1B are the unit length hinge axes as computed from bodyA and
+	// bodyB, we need to rotate both bodies along the axis u = (ax1 x ax2).
+	// if "theta" is the angle between ax1 and ax2, we need an angular velocity
+	// along u to cover angle erp*theta in one step :
+	//   |angular_velocity| = angle/time = erp*theta / stepsize
+	//                      = (erp*fps) * theta
+	//    angular_velocity  = |angular_velocity| * (ax1 x ax2) / |ax1 x ax2|
+	//                      = (erp*fps) * theta * (ax1 x ax2) / sin(theta)
+	// ...as ax1 and ax2 are unit length. if theta is smallish,
+	// theta ~= sin(theta), so
+	//    angular_velocity  = (erp*fps) * (ax1 x ax2)
+	// ax1 x ax2 is in the plane space of ax1, so we project the angular
+	// velocity to p and q to find the right hand side.
+	k = info->fps * normalErp;//??
+
+	btVector3 u = ax1A.cross(ax1B);
+	info->m_constraintError[s3] = k * u.dot(p);
+	info->m_constraintError[s4] = k * u.dot(q);
+#endif
+	// check angular limits
+	nrow = 4; // last filled row
+	int srow;
+	btScalar limit_err = btScalar(0.0);
+	int limit = 0;
+	if(getSolveLimit())
+	{
+#ifdef	_BT_USE_CENTER_LIMIT_
+	limit_err = m_limit.getCorrection() * m_referenceSign;
+#else
+	limit_err = m_correction * m_referenceSign;
+#endif
+	limit = (limit_err > btScalar(0.0)) ? 1 : 2;
+
+	}
+	// if the hinge has joint limits or motor, add in the extra row
+	bool powered = getEnableAngularMotor();
+	if(limit || powered)
+	{
+		nrow++;
+		srow = nrow * info->rowskip;
+		info->m_J1angularAxis[srow+0] = ax1[0];
+		info->m_J1angularAxis[srow+1] = ax1[1];
+		info->m_J1angularAxis[srow+2] = ax1[2];
+
+		info->m_J2angularAxis[srow+0] = -ax1[0];
+		info->m_J2angularAxis[srow+1] = -ax1[1];
+		info->m_J2angularAxis[srow+2] = -ax1[2];
+
+		btScalar lostop = getLowerLimit();
+		btScalar histop = getUpperLimit();
+		if(limit && (lostop == histop))
+		{  // the joint motor is ineffective
+			powered = false;
+		}
+		info->m_constraintError[srow] = btScalar(0.0f);
+		btScalar currERP = (m_flags & BT_HINGE_FLAGS_ERP_STOP) ? m_stopERP : normalErp;
+		if(powered)
+		{
+			if(m_flags & BT_HINGE_FLAGS_CFM_NORM)
+			{
+				info->cfm[srow] = m_normalCFM;
+			}
+			btScalar mot_fact = getMotorFactor(m_hingeAngle, lostop, histop, m_motorTargetVelocity, info->fps * currERP);
+			info->m_constraintError[srow] += mot_fact * m_motorTargetVelocity * m_referenceSign;
+			info->m_lowerLimit[srow] = - m_maxMotorImpulse;
+			info->m_upperLimit[srow] =   m_maxMotorImpulse;
+		}
+		if(limit)
+		{
+			k = info->fps * currERP;
+			info->m_constraintError[srow] += k * limit_err;
+			if(m_flags & BT_HINGE_FLAGS_CFM_STOP)
+			{
+				info->cfm[srow] = m_stopCFM;
+			}
+			if(lostop == histop) 
+			{
+				// limited low and high simultaneously
+				info->m_lowerLimit[srow] = -SIMD_INFINITY;
+				info->m_upperLimit[srow] = SIMD_INFINITY;
+			}
+			else if(limit == 1) 
+			{ // low limit
+				info->m_lowerLimit[srow] = 0;
+				info->m_upperLimit[srow] = SIMD_INFINITY;
+			}
+			else 
+			{ // high limit
+				info->m_lowerLimit[srow] = -SIMD_INFINITY;
+				info->m_upperLimit[srow] = 0;
+			}
+			// bounce (we'll use slider parameter abs(1.0 - m_dampingLimAng) for that)
+#ifdef	_BT_USE_CENTER_LIMIT_
+			btScalar bounce = m_limit.getRelaxationFactor();
+#else
+			btScalar bounce = m_relaxationFactor;
+#endif
+			if(bounce > btScalar(0.0))
+			{
+				btScalar vel = angVelA.dot(ax1);
+				vel -= angVelB.dot(ax1);
+				// only apply bounce if the velocity is incoming, and if the
+				// resulting c[] exceeds what we already have.
+				if(limit == 1)
+				{	// low limit
+					if(vel < 0)
+					{
+						btScalar newc = -bounce * vel;
+						if(newc > info->m_constraintError[srow])
+						{
+							info->m_constraintError[srow] = newc;
+						}
+					}
+				}
+				else
+				{	// high limit - all those computations are reversed
+					if(vel > 0)
+					{
+						btScalar newc = -bounce * vel;
+						if(newc < info->m_constraintError[srow])
+						{
+							info->m_constraintError[srow] = newc;
+						}
+					}
+				}
+			}
+#ifdef	_BT_USE_CENTER_LIMIT_
+			info->m_constraintError[srow] *= m_limit.getBiasFactor();
+#else
+			info->m_constraintError[srow] *= m_biasFactor;
+#endif
+		} // if(limit)
+	} // if angular limit or powered
+}
+
+
+///override the default global value of a parameter (such as ERP or CFM), optionally provide the axis (0..5). 
+///If no axis is provided, it uses the default axis for this constraint.
+void btHingeConstraint::setParam(int num, btScalar value, int axis)
+{
+	if((axis == -1) || (axis == 5))
+	{
+		switch(num)
+		{	
+			case BT_CONSTRAINT_STOP_ERP :
+				m_stopERP = value;
+				m_flags |= BT_HINGE_FLAGS_ERP_STOP;
+				break;
+			case BT_CONSTRAINT_STOP_CFM :
+				m_stopCFM = value;
+				m_flags |= BT_HINGE_FLAGS_CFM_STOP;
+				break;
+			case BT_CONSTRAINT_CFM :
+				m_normalCFM = value;
+				m_flags |= BT_HINGE_FLAGS_CFM_NORM;
+				break;
+			case BT_CONSTRAINT_ERP:
+				m_normalERP = value;
+				m_flags |= BT_HINGE_FLAGS_ERP_NORM;
+				break;
+			default : 
+				btAssertConstrParams(0);
+		}
+	}
+	else
+	{
+		btAssertConstrParams(0);
+	}
+}
+
+///return the local value of parameter
+btScalar btHingeConstraint::getParam(int num, int axis) const 
+{
+	btScalar retVal = 0;
+	if((axis == -1) || (axis == 5))
+	{
+		switch(num)
+		{	
+			case BT_CONSTRAINT_STOP_ERP :
+				btAssertConstrParams(m_flags & BT_HINGE_FLAGS_ERP_STOP);
+				retVal = m_stopERP;
+				break;
+			case BT_CONSTRAINT_STOP_CFM :
+				btAssertConstrParams(m_flags & BT_HINGE_FLAGS_CFM_STOP);
+				retVal = m_stopCFM;
+				break;
+			case BT_CONSTRAINT_CFM :
+				btAssertConstrParams(m_flags & BT_HINGE_FLAGS_CFM_NORM);
+				retVal = m_normalCFM;
+				break;
+			case BT_CONSTRAINT_ERP:
+				btAssertConstrParams(m_flags & BT_HINGE_FLAGS_ERP_NORM);
+				retVal = m_normalERP;
+				break;
+			default : 
+				btAssertConstrParams(0);
+		}
+	}
+	else
+	{
+		btAssertConstrParams(0);
+	}
+	return retVal;
+}
+
+