godot/servers/physics/joints/generic_6dof_joint_sw.cpp

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/*  generic_6dof_joint_sw.cpp                                            */
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/* Copyright (c) 2007-2017 Juan Linietsky, Ariel Manzur.                 */
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/*
Adapted to Godot from the Bullet library.
*/

/*
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.
*/

/*
2007-09-09
Generic6DOFJointSW Refactored by Francisco Le?n
email: projectileman@yahoo.com
http://gimpact.sf.net
*/

#include "generic_6dof_joint_sw.h"

#define GENERIC_D6_DISABLE_WARMSTARTING 1

//////////////////////////// G6DOFRotationalLimitMotorSW ////////////////////////////////////

int G6DOFRotationalLimitMotorSW::testLimitValue(real_t test_value) {
	if (m_loLimit > m_hiLimit) {
		m_currentLimit = 0; //Free from violation
		return 0;
	}

	if (test_value < m_loLimit) {
		m_currentLimit = 1; //low limit violation
		m_currentLimitError = test_value - m_loLimit;
		return 1;
	} else if (test_value > m_hiLimit) {
		m_currentLimit = 2; //High limit violation
		m_currentLimitError = test_value - m_hiLimit;
		return 2;
	};

	m_currentLimit = 0; //Free from violation
	return 0;
}

real_t G6DOFRotationalLimitMotorSW::solveAngularLimits(
		real_t timeStep, Vector3 &axis, real_t jacDiagABInv,
		BodySW *body0, BodySW *body1) {
	if (needApplyTorques() == false) return 0.0f;

	real_t target_velocity = m_targetVelocity;
	real_t maxMotorForce = m_maxMotorForce;

	//current error correction
	if (m_currentLimit != 0) {
		target_velocity = -m_ERP * m_currentLimitError / (timeStep);
		maxMotorForce = m_maxLimitForce;
	}

	maxMotorForce *= timeStep;

	// current velocity difference
	Vector3 vel_diff = body0->get_angular_velocity();
	if (body1) {
		vel_diff -= body1->get_angular_velocity();
	}

	real_t rel_vel = axis.dot(vel_diff);

	// correction velocity
	real_t motor_relvel = m_limitSoftness * (target_velocity - m_damping * rel_vel);

	if (motor_relvel < CMP_EPSILON && motor_relvel > -CMP_EPSILON) {
		return 0.0f; //no need for applying force
	}

	// correction impulse
	real_t unclippedMotorImpulse = (1 + m_bounce) * motor_relvel * jacDiagABInv;

	// clip correction impulse
	real_t clippedMotorImpulse;

	///@todo: should clip against accumulated impulse
	if (unclippedMotorImpulse > 0.0f) {
		clippedMotorImpulse = unclippedMotorImpulse > maxMotorForce ? maxMotorForce : unclippedMotorImpulse;
	} else {
		clippedMotorImpulse = unclippedMotorImpulse < -maxMotorForce ? -maxMotorForce : unclippedMotorImpulse;
	}

	// sort with accumulated impulses
	real_t lo = real_t(-1e30);
	real_t hi = real_t(1e30);

	real_t oldaccumImpulse = m_accumulatedImpulse;
	real_t sum = oldaccumImpulse + clippedMotorImpulse;
	m_accumulatedImpulse = sum > hi ? real_t(0.) : sum < lo ? real_t(0.) : sum;

	clippedMotorImpulse = m_accumulatedImpulse - oldaccumImpulse;

	Vector3 motorImp = clippedMotorImpulse * axis;

	body0->apply_torque_impulse(motorImp);
	if (body1) body1->apply_torque_impulse(-motorImp);

	return clippedMotorImpulse;
}

//////////////////////////// End G6DOFRotationalLimitMotorSW ////////////////////////////////////

//////////////////////////// G6DOFTranslationalLimitMotorSW ////////////////////////////////////
real_t G6DOFTranslationalLimitMotorSW::solveLinearAxis(
		real_t timeStep,
		real_t jacDiagABInv,
		BodySW *body1, const Vector3 &pointInA,
		BodySW *body2, const Vector3 &pointInB,
		int limit_index,
		const Vector3 &axis_normal_on_a,
		const Vector3 &anchorPos) {

	///find relative velocity
	//    Vector3 rel_pos1 = pointInA - body1->get_transform().origin;
	//    Vector3 rel_pos2 = pointInB - body2->get_transform().origin;
	Vector3 rel_pos1 = anchorPos - body1->get_transform().origin;
	Vector3 rel_pos2 = anchorPos - body2->get_transform().origin;

	Vector3 vel1 = body1->get_velocity_in_local_point(rel_pos1);
	Vector3 vel2 = body2->get_velocity_in_local_point(rel_pos2);
	Vector3 vel = vel1 - vel2;

	real_t rel_vel = axis_normal_on_a.dot(vel);

	/// apply displacement correction

	//positional error (zeroth order error)
	real_t depth = -(pointInA - pointInB).dot(axis_normal_on_a);
	real_t lo = real_t(-1e30);
	real_t hi = real_t(1e30);

	real_t minLimit = m_lowerLimit[limit_index];
	real_t maxLimit = m_upperLimit[limit_index];

	//handle the limits
	if (minLimit < maxLimit) {
		{
			if (depth > maxLimit) {
				depth -= maxLimit;
				lo = real_t(0.);

			} else {
				if (depth < minLimit) {
					depth -= minLimit;
					hi = real_t(0.);
				} else {
					return 0.0f;
				}
			}
		}
	}

	real_t normalImpulse = m_limitSoftness[limit_index] * (m_restitution[limit_index] * depth / timeStep - m_damping[limit_index] * rel_vel) * jacDiagABInv;

	real_t oldNormalImpulse = m_accumulatedImpulse[limit_index];
	real_t sum = oldNormalImpulse + normalImpulse;
	m_accumulatedImpulse[limit_index] = sum > hi ? real_t(0.) : sum < lo ? real_t(0.) : sum;
	normalImpulse = m_accumulatedImpulse[limit_index] - oldNormalImpulse;

	Vector3 impulse_vector = axis_normal_on_a * normalImpulse;
	body1->apply_impulse(rel_pos1, impulse_vector);
	body2->apply_impulse(rel_pos2, -impulse_vector);
	return normalImpulse;
}

//////////////////////////// G6DOFTranslationalLimitMotorSW ////////////////////////////////////

Generic6DOFJointSW::Generic6DOFJointSW(BodySW *rbA, BodySW *rbB, const Transform &frameInA, const Transform &frameInB, bool useLinearReferenceFrameA)
	: JointSW(_arr, 2), m_frameInA(frameInA), m_frameInB(frameInB),
	  m_useLinearReferenceFrameA(useLinearReferenceFrameA) {
	A = rbA;
	B = rbB;
	A->add_constraint(this, 0);
	B->add_constraint(this, 1);
}

void Generic6DOFJointSW::calculateAngleInfo() {
	Basis relative_frame = m_calculatedTransformA.basis.inverse() * m_calculatedTransformB.basis;

	m_calculatedAxisAngleDiff = relative_frame.get_euler();

	// in euler angle mode we do not actually constrain the angular velocity
	// along the axes axis[0] and axis[2] (although we do use axis[1]) :
	//
	//    to get			constrain w2-w1 along		...not
	//    ------			---------------------		------
	//    d(angle[0])/dt = 0	ax[1] x ax[2]			ax[0]
	//    d(angle[1])/dt = 0	ax[1]
	//    d(angle[2])/dt = 0	ax[0] x ax[1]			ax[2]
	//
	// constraining w2-w1 along an axis 'a' means that a'*(w2-w1)=0.
	// to prove the result for angle[0], write the expression for angle[0] from
	// GetInfo1 then take the derivative. to prove this for angle[2] it is
	// easier to take the euler rate expression for d(angle[2])/dt with respect
	// to the components of w and set that to 0.

	Vector3 axis0 = m_calculatedTransformB.basis.get_axis(0);
	Vector3 axis2 = m_calculatedTransformA.basis.get_axis(2);

	m_calculatedAxis[1] = axis2.cross(axis0);
	m_calculatedAxis[0] = m_calculatedAxis[1].cross(axis2);
	m_calculatedAxis[2] = axis0.cross(m_calculatedAxis[1]);

	/*
	if(m_debugDrawer)
	{

		char buff[300];
		sprintf(buff,"\n X: %.2f ; Y: %.2f ; Z: %.2f ",
		m_calculatedAxisAngleDiff[0],
		m_calculatedAxisAngleDiff[1],
		m_calculatedAxisAngleDiff[2]);
		m_debugDrawer->reportErrorWarning(buff);
	}
	*/
}

void Generic6DOFJointSW::calculateTransforms() {
	m_calculatedTransformA = A->get_transform() * m_frameInA;
	m_calculatedTransformB = B->get_transform() * m_frameInB;

	calculateAngleInfo();
}

void Generic6DOFJointSW::buildLinearJacobian(
		JacobianEntrySW &jacLinear, const Vector3 &normalWorld,
		const Vector3 &pivotAInW, const Vector3 &pivotBInW) {
	memnew_placement(&jacLinear, JacobianEntrySW(
										 A->get_principal_inertia_axes().transposed(),
										 B->get_principal_inertia_axes().transposed(),
										 pivotAInW - A->get_transform().origin - A->get_center_of_mass(),
										 pivotBInW - B->get_transform().origin - B->get_center_of_mass(),
										 normalWorld,
										 A->get_inv_inertia(),
										 A->get_inv_mass(),
										 B->get_inv_inertia(),
										 B->get_inv_mass()));
}

void Generic6DOFJointSW::buildAngularJacobian(
		JacobianEntrySW &jacAngular, const Vector3 &jointAxisW) {
	memnew_placement(&jacAngular, JacobianEntrySW(jointAxisW,
										  A->get_principal_inertia_axes().transposed(),
										  B->get_principal_inertia_axes().transposed(),
										  A->get_inv_inertia(),
										  B->get_inv_inertia()));
}

bool Generic6DOFJointSW::testAngularLimitMotor(int axis_index) {
	real_t angle = m_calculatedAxisAngleDiff[axis_index];

	//test limits
	m_angularLimits[axis_index].testLimitValue(angle);
	return m_angularLimits[axis_index].needApplyTorques();
}

bool Generic6DOFJointSW::setup(real_t p_timestep) {

	// Clear accumulated impulses for the next simulation step
	m_linearLimits.m_accumulatedImpulse = Vector3(real_t(0.), real_t(0.), real_t(0.));
	int i;
	for (i = 0; i < 3; i++) {
		m_angularLimits[i].m_accumulatedImpulse = real_t(0.);
	}
	//calculates transform
	calculateTransforms();

	//  const Vector3& pivotAInW = m_calculatedTransformA.origin;
	//  const Vector3& pivotBInW = m_calculatedTransformB.origin;
	calcAnchorPos();
	Vector3 pivotAInW = m_AnchorPos;
	Vector3 pivotBInW = m_AnchorPos;

	// not used here
	//    Vector3 rel_pos1 = pivotAInW - A->get_transform().origin;
	//    Vector3 rel_pos2 = pivotBInW - B->get_transform().origin;

	Vector3 normalWorld;
	//linear part
	for (i = 0; i < 3; i++) {
		if (m_linearLimits.enable_limit[i] && m_linearLimits.isLimited(i)) {
			if (m_useLinearReferenceFrameA)
				normalWorld = m_calculatedTransformA.basis.get_axis(i);
			else
				normalWorld = m_calculatedTransformB.basis.get_axis(i);

			buildLinearJacobian(
					m_jacLinear[i], normalWorld,
					pivotAInW, pivotBInW);
		}
	}

	// angular part
	for (i = 0; i < 3; i++) {
		//calculates error angle
		if (m_angularLimits[i].m_enableLimit && testAngularLimitMotor(i)) {
			normalWorld = this->getAxis(i);
			// Create angular atom
			buildAngularJacobian(m_jacAng[i], normalWorld);
		}
	}

	return true;
}

void Generic6DOFJointSW::solve(real_t p_timestep) {
	m_timeStep = p_timestep;

	//calculateTransforms();

	int i;

	// linear

	Vector3 pointInA = m_calculatedTransformA.origin;
	Vector3 pointInB = m_calculatedTransformB.origin;

	real_t jacDiagABInv;
	Vector3 linear_axis;
	for (i = 0; i < 3; i++) {
		if (m_linearLimits.enable_limit[i] && m_linearLimits.isLimited(i)) {
			jacDiagABInv = real_t(1.) / m_jacLinear[i].getDiagonal();

			if (m_useLinearReferenceFrameA)
				linear_axis = m_calculatedTransformA.basis.get_axis(i);
			else
				linear_axis = m_calculatedTransformB.basis.get_axis(i);

			m_linearLimits.solveLinearAxis(
					m_timeStep,
					jacDiagABInv,
					A, pointInA,
					B, pointInB,
					i, linear_axis, m_AnchorPos);
		}
	}

	// angular
	Vector3 angular_axis;
	real_t angularJacDiagABInv;
	for (i = 0; i < 3; i++) {
		if (m_angularLimits[i].m_enableLimit && m_angularLimits[i].needApplyTorques()) {

			// get axis
			angular_axis = getAxis(i);

			angularJacDiagABInv = real_t(1.) / m_jacAng[i].getDiagonal();

			m_angularLimits[i].solveAngularLimits(m_timeStep, angular_axis, angularJacDiagABInv, A, B);
		}
	}
}

void Generic6DOFJointSW::updateRHS(real_t timeStep) {
	(void)timeStep;
}

Vector3 Generic6DOFJointSW::getAxis(int axis_index) const {
	return m_calculatedAxis[axis_index];
}

real_t Generic6DOFJointSW::getAngle(int axis_index) const {
	return m_calculatedAxisAngleDiff[axis_index];
}

void Generic6DOFJointSW::calcAnchorPos(void) {
	real_t imA = A->get_inv_mass();
	real_t imB = B->get_inv_mass();
	real_t weight;
	if (imB == real_t(0.0)) {
		weight = real_t(1.0);
	} else {
		weight = imA / (imA + imB);
	}
	const Vector3 &pA = m_calculatedTransformA.origin;
	const Vector3 &pB = m_calculatedTransformB.origin;
	m_AnchorPos = pA * weight + pB * (real_t(1.0) - weight);
	return;
} // Generic6DOFJointSW::calcAnchorPos()

void Generic6DOFJointSW::set_param(Vector3::Axis p_axis, PhysicsServer::G6DOFJointAxisParam p_param, real_t p_value) {

	ERR_FAIL_INDEX(p_axis, 3);
	switch (p_param) {
		case PhysicsServer::G6DOF_JOINT_LINEAR_LOWER_LIMIT: {

			m_linearLimits.m_lowerLimit[p_axis] = p_value;
		} break;
		case PhysicsServer::G6DOF_JOINT_LINEAR_UPPER_LIMIT: {

			m_linearLimits.m_upperLimit[p_axis] = p_value;

		} break;
		case PhysicsServer::G6DOF_JOINT_LINEAR_LIMIT_SOFTNESS: {

			m_linearLimits.m_limitSoftness[p_axis] = p_value;

		} break;
		case PhysicsServer::G6DOF_JOINT_LINEAR_RESTITUTION: {

			m_linearLimits.m_restitution[p_axis] = p_value;

		} break;
		case PhysicsServer::G6DOF_JOINT_LINEAR_DAMPING: {

			m_linearLimits.m_damping[p_axis] = p_value;

		} break;
		case PhysicsServer::G6DOF_JOINT_ANGULAR_LOWER_LIMIT: {

			m_angularLimits[p_axis].m_loLimit = p_value;

		} break;
		case PhysicsServer::G6DOF_JOINT_ANGULAR_UPPER_LIMIT: {

			m_angularLimits[p_axis].m_hiLimit = p_value;

		} break;
		case PhysicsServer::G6DOF_JOINT_ANGULAR_LIMIT_SOFTNESS: {

			m_angularLimits[p_axis].m_limitSoftness = p_value;

		} break;
		case PhysicsServer::G6DOF_JOINT_ANGULAR_DAMPING: {

			m_angularLimits[p_axis].m_damping = p_value;

		} break;
		case PhysicsServer::G6DOF_JOINT_ANGULAR_RESTITUTION: {

			m_angularLimits[p_axis].m_bounce = p_value;

		} break;
		case PhysicsServer::G6DOF_JOINT_ANGULAR_FORCE_LIMIT: {

			m_angularLimits[p_axis].m_maxLimitForce = p_value;

		} break;
		case PhysicsServer::G6DOF_JOINT_ANGULAR_ERP: {

			m_angularLimits[p_axis].m_ERP = p_value;

		} break;
		case PhysicsServer::G6DOF_JOINT_ANGULAR_MOTOR_TARGET_VELOCITY: {

			m_angularLimits[p_axis].m_targetVelocity = p_value;

		} break;
		case PhysicsServer::G6DOF_JOINT_ANGULAR_MOTOR_FORCE_LIMIT: {

			m_angularLimits[p_axis].m_maxLimitForce = p_value;

		} break;
	}
}

real_t Generic6DOFJointSW::get_param(Vector3::Axis p_axis, PhysicsServer::G6DOFJointAxisParam p_param) const {
	ERR_FAIL_INDEX_V(p_axis, 3, 0);
	switch (p_param) {
		case PhysicsServer::G6DOF_JOINT_LINEAR_LOWER_LIMIT: {

			return m_linearLimits.m_lowerLimit[p_axis];
		} break;
		case PhysicsServer::G6DOF_JOINT_LINEAR_UPPER_LIMIT: {

			return m_linearLimits.m_upperLimit[p_axis];

		} break;
		case PhysicsServer::G6DOF_JOINT_LINEAR_LIMIT_SOFTNESS: {

			return m_linearLimits.m_limitSoftness[p_axis];

		} break;
		case PhysicsServer::G6DOF_JOINT_LINEAR_RESTITUTION: {

			return m_linearLimits.m_restitution[p_axis];

		} break;
		case PhysicsServer::G6DOF_JOINT_LINEAR_DAMPING: {

			return m_linearLimits.m_damping[p_axis];

		} break;
		case PhysicsServer::G6DOF_JOINT_ANGULAR_LOWER_LIMIT: {

			return m_angularLimits[p_axis].m_loLimit;

		} break;
		case PhysicsServer::G6DOF_JOINT_ANGULAR_UPPER_LIMIT: {

			return m_angularLimits[p_axis].m_hiLimit;

		} break;
		case PhysicsServer::G6DOF_JOINT_ANGULAR_LIMIT_SOFTNESS: {

			return m_angularLimits[p_axis].m_limitSoftness;

		} break;
		case PhysicsServer::G6DOF_JOINT_ANGULAR_DAMPING: {

			return m_angularLimits[p_axis].m_damping;

		} break;
		case PhysicsServer::G6DOF_JOINT_ANGULAR_RESTITUTION: {

			return m_angularLimits[p_axis].m_bounce;

		} break;
		case PhysicsServer::G6DOF_JOINT_ANGULAR_FORCE_LIMIT: {

			return m_angularLimits[p_axis].m_maxLimitForce;

		} break;
		case PhysicsServer::G6DOF_JOINT_ANGULAR_ERP: {

			return m_angularLimits[p_axis].m_ERP;

		} break;
		case PhysicsServer::G6DOF_JOINT_ANGULAR_MOTOR_TARGET_VELOCITY: {

			return m_angularLimits[p_axis].m_targetVelocity;

		} break;
		case PhysicsServer::G6DOF_JOINT_ANGULAR_MOTOR_FORCE_LIMIT: {

			return m_angularLimits[p_axis].m_maxMotorForce;

		} break;
	}
	return 0;
}

void Generic6DOFJointSW::set_flag(Vector3::Axis p_axis, PhysicsServer::G6DOFJointAxisFlag p_flag, bool p_value) {

	ERR_FAIL_INDEX(p_axis, 3);

	switch (p_flag) {
		case PhysicsServer::G6DOF_JOINT_FLAG_ENABLE_LINEAR_LIMIT: {

			m_linearLimits.enable_limit[p_axis] = p_value;
		} break;
		case PhysicsServer::G6DOF_JOINT_FLAG_ENABLE_ANGULAR_LIMIT: {

			m_angularLimits[p_axis].m_enableLimit = p_value;
		} break;
		case PhysicsServer::G6DOF_JOINT_FLAG_ENABLE_MOTOR: {

			m_angularLimits[p_axis].m_enableMotor = p_value;
		} break;
	}
}
bool Generic6DOFJointSW::get_flag(Vector3::Axis p_axis, PhysicsServer::G6DOFJointAxisFlag p_flag) const {

	ERR_FAIL_INDEX_V(p_axis, 3, 0);
	switch (p_flag) {
		case PhysicsServer::G6DOF_JOINT_FLAG_ENABLE_LINEAR_LIMIT: {

			return m_linearLimits.enable_limit[p_axis];
		} break;
		case PhysicsServer::G6DOF_JOINT_FLAG_ENABLE_ANGULAR_LIMIT: {

			return m_angularLimits[p_axis].m_enableLimit;
		} break;
		case PhysicsServer::G6DOF_JOINT_FLAG_ENABLE_MOTOR: {

			return m_angularLimits[p_axis].m_enableMotor;
		} break;
	}

	return 0;
}