1 files changed, 172 insertions, 0 deletions
diff --git a/thirdparty/bullet/BulletDynamics/Featherstone/btMultiBodySphericalJointMotor.cpp b/thirdparty/bullet/BulletDynamics/Featherstone/btMultiBodySphericalJointMotor.cpp
new file mode 100644
index 0000000000..3e5aa30f28
--- /dev/null
+++ b/thirdparty/bullet/BulletDynamics/Featherstone/btMultiBodySphericalJointMotor.cpp
@@ -0,0 +1,172 @@
+/*
+Bullet Continuous Collision Detection and Physics Library
+Copyright (c) 2018 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.
+*/
+
+///This file was written by Erwin Coumans
+
+#include "btMultiBodySphericalJointMotor.h"
+#include "btMultiBody.h"
+#include "btMultiBodyLinkCollider.h"
+#include "BulletCollision/CollisionDispatch/btCollisionObject.h"
+#include "LinearMath/btTransformUtil.h"
+#include "BulletDynamics/ConstraintSolver/btGeneric6DofSpring2Constraint.h"
+
+btMultiBodySphericalJointMotor::btMultiBodySphericalJointMotor(btMultiBody* body, int link, btScalar maxMotorImpulse)
+	: btMultiBodyConstraint(body, body, link, body->getLink(link).m_parent, 3, true),
+	m_desiredVelocity(0, 0, 0),
+	m_desiredPosition(0,0,0,1),
+	m_kd(1.),
+	m_kp(0.2),
+	m_erp(1),
+	m_rhsClamp(SIMD_INFINITY)
+{
+
+	m_maxAppliedImpulse = maxMotorImpulse;
+}
+
+
+void btMultiBodySphericalJointMotor::finalizeMultiDof()
+{
+	allocateJacobiansMultiDof();
+	// note: we rely on the fact that data.m_jacobians are
+	// always initialized to zero by the Constraint ctor
+	int linkDoF = 0;
+	unsigned int offset = 6 + (m_bodyA->getLink(m_linkA).m_dofOffset + linkDoF);
+
+	// row 0: the lower bound
+	// row 0: the lower bound
+	jacobianA(0)[offset] = 1;
+
+	m_numDofsFinalized = m_jacSizeBoth;
+}
+
+
+btMultiBodySphericalJointMotor::~btMultiBodySphericalJointMotor()
+{
+}
+
+int btMultiBodySphericalJointMotor::getIslandIdA() const
+{
+	if (this->m_linkA < 0)
+	{
+		btMultiBodyLinkCollider* col = m_bodyA->getBaseCollider();
+		if (col)
+			return col->getIslandTag();
+	}
+	else
+	{
+		if (m_bodyA->getLink(m_linkA).m_collider)
+		{
+			return m_bodyA->getLink(m_linkA).m_collider->getIslandTag();
+		}
+	}
+	return -1;
+}
+
+int btMultiBodySphericalJointMotor::getIslandIdB() const
+{
+	if (m_linkB < 0)
+	{
+		btMultiBodyLinkCollider* col = m_bodyB->getBaseCollider();
+		if (col)
+			return col->getIslandTag();
+	}
+	else
+	{
+		if (m_bodyB->getLink(m_linkB).m_collider)
+		{
+			return m_bodyB->getLink(m_linkB).m_collider->getIslandTag();
+		}
+	}
+	return -1;
+}
+
+void btMultiBodySphericalJointMotor::createConstraintRows(btMultiBodyConstraintArray& constraintRows,
+												 btMultiBodyJacobianData& data,
+												 const btContactSolverInfo& infoGlobal)
+{
+	// only positions need to be updated -- data.m_jacobians and force
+	// directions were set in the ctor and never change.
+
+	if (m_numDofsFinalized != m_jacSizeBoth)
+	{
+		finalizeMultiDof();
+	}
+
+	//don't crash
+	if (m_numDofsFinalized != m_jacSizeBoth)
+		return;
+	
+
+	if (m_maxAppliedImpulse == 0.f)
+		return;
+
+	const btScalar posError = 0;
+	const btVector3 dummy(0, 0, 0);
+
+	
+	btVector3 axis[3] = { btVector3(1, 0, 0), btVector3(0, 1, 0), btVector3(0, 0, 1) };
+	
+	btQuaternion desiredQuat = m_desiredPosition;
+	btQuaternion currentQuat(m_bodyA->getJointPosMultiDof(m_linkA)[0],
+		m_bodyA->getJointPosMultiDof(m_linkA)[1],
+		m_bodyA->getJointPosMultiDof(m_linkA)[2],
+		m_bodyA->getJointPosMultiDof(m_linkA)[3]);
+
+btQuaternion relRot = currentQuat.inverse() * desiredQuat;
+	btVector3 angleDiff;
+	btGeneric6DofSpring2Constraint::matrixToEulerXYZ(btMatrix3x3(relRot), angleDiff);
+
+
+
+	for (int row = 0; row < getNumRows(); row++)
+	{
+		btMultiBodySolverConstraint& constraintRow = constraintRows.expandNonInitializing();
+
+		int dof = row;
+		
+		btScalar currentVelocity = m_bodyA->getJointVelMultiDof(m_linkA)[dof];
+		btScalar desiredVelocity = this->m_desiredVelocity[row];
+		
+		btScalar velocityError = desiredVelocity - currentVelocity;
+
+		btMatrix3x3 frameAworld;
+		frameAworld.setIdentity();
+		frameAworld = m_bodyA->localFrameToWorld(m_linkA, frameAworld);
+		btScalar posError = 0;
+		{
+			btAssert(m_bodyA->getLink(m_linkA).m_jointType == btMultibodyLink::eSpherical);
+			switch (m_bodyA->getLink(m_linkA).m_jointType)
+			{
+				case btMultibodyLink::eSpherical:
+				{
+					btVector3 constraintNormalAng = frameAworld.getColumn(row % 3);
+					posError = m_kp*angleDiff[row % 3];
+					fillMultiBodyConstraint(constraintRow, data, 0, 0, constraintNormalAng,
+						btVector3(0,0,0), dummy, dummy,
+						posError,
+						infoGlobal,
+						-m_maxAppliedImpulse, m_maxAppliedImpulse, true);
+					constraintRow.m_orgConstraint = this;
+					constraintRow.m_orgDofIndex = row;
+					break;
+				}
+				default:
+				{
+					btAssert(0);
+				}
+			};
+		}
+	}
+}