virtualx-engine/servers/physics/joints/slider_joint_sw.cpp

/*************************************************************************/
/*  slider_joint_sw.cpp                                                  */
/*************************************************************************/
/*                       This file is part of:                           */
/*                           GODOT ENGINE                                */
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/* Copyright (c) 2007-2017 Juan Linietsky, Ariel Manzur.                 */
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/*
Adapted to Godot from the Bullet library.
See corresponding header file for licensing info.
*/

#include "slider_joint_sw.h"

//-----------------------------------------------------------------------------

static _FORCE_INLINE_ real_t atan2fast(real_t y, real_t x) {
	real_t coeff_1 = Math_PI / 4.0f;
	real_t coeff_2 = 3.0f * coeff_1;
	real_t abs_y = Math::abs(y);
	real_t angle;
	if (x >= 0.0f) {
		real_t r = (x - abs_y) / (x + abs_y);
		angle = coeff_1 - coeff_1 * r;
	} else {
		real_t r = (x + abs_y) / (abs_y - x);
		angle = coeff_2 - coeff_1 * r;
	}
	return (y < 0.0f) ? -angle : angle;
}

void SliderJointSW::initParams() {
	m_lowerLinLimit = real_t(1.0);
	m_upperLinLimit = real_t(-1.0);
	m_lowerAngLimit = real_t(0.);
	m_upperAngLimit = real_t(0.);
	m_softnessDirLin = SLIDER_CONSTRAINT_DEF_SOFTNESS;
	m_restitutionDirLin = SLIDER_CONSTRAINT_DEF_RESTITUTION;
	m_dampingDirLin = real_t(0.);
	m_softnessDirAng = SLIDER_CONSTRAINT_DEF_SOFTNESS;
	m_restitutionDirAng = SLIDER_CONSTRAINT_DEF_RESTITUTION;
	m_dampingDirAng = real_t(0.);
	m_softnessOrthoLin = SLIDER_CONSTRAINT_DEF_SOFTNESS;
	m_restitutionOrthoLin = SLIDER_CONSTRAINT_DEF_RESTITUTION;
	m_dampingOrthoLin = SLIDER_CONSTRAINT_DEF_DAMPING;
	m_softnessOrthoAng = SLIDER_CONSTRAINT_DEF_SOFTNESS;
	m_restitutionOrthoAng = SLIDER_CONSTRAINT_DEF_RESTITUTION;
	m_dampingOrthoAng = SLIDER_CONSTRAINT_DEF_DAMPING;
	m_softnessLimLin = SLIDER_CONSTRAINT_DEF_SOFTNESS;
	m_restitutionLimLin = SLIDER_CONSTRAINT_DEF_RESTITUTION;
	m_dampingLimLin = SLIDER_CONSTRAINT_DEF_DAMPING;
	m_softnessLimAng = SLIDER_CONSTRAINT_DEF_SOFTNESS;
	m_restitutionLimAng = SLIDER_CONSTRAINT_DEF_RESTITUTION;
	m_dampingLimAng = SLIDER_CONSTRAINT_DEF_DAMPING;

	m_poweredLinMotor = false;
	m_targetLinMotorVelocity = real_t(0.);
	m_maxLinMotorForce = real_t(0.);
	m_accumulatedLinMotorImpulse = real_t(0.0);

	m_poweredAngMotor = false;
	m_targetAngMotorVelocity = real_t(0.);
	m_maxAngMotorForce = real_t(0.);
	m_accumulatedAngMotorImpulse = real_t(0.0);

} // SliderJointSW::initParams()

//-----------------------------------------------------------------------------

//-----------------------------------------------------------------------------

SliderJointSW::SliderJointSW(BodySW *rbA, BodySW *rbB, const Transform &frameInA, const Transform &frameInB)
	: JointSW(_arr, 2), m_frameInA(frameInA), m_frameInB(frameInB) {

	A = rbA;
	B = rbB;

	A->add_constraint(this, 0);
	B->add_constraint(this, 1);

	initParams();
} // SliderJointSW::SliderJointSW()

//-----------------------------------------------------------------------------

bool SliderJointSW::setup(float p_step) {

	//calculate transforms
	m_calculatedTransformA = A->get_transform() * m_frameInA;
	m_calculatedTransformB = B->get_transform() * m_frameInB;
	m_realPivotAInW = m_calculatedTransformA.origin;
	m_realPivotBInW = m_calculatedTransformB.origin;
	m_sliderAxis = m_calculatedTransformA.basis.get_axis(0); // along X
	m_delta = m_realPivotBInW - m_realPivotAInW;
	m_projPivotInW = m_realPivotAInW + m_sliderAxis.dot(m_delta) * m_sliderAxis;
	m_relPosA = m_projPivotInW - A->get_transform().origin;
	m_relPosB = m_realPivotBInW - B->get_transform().origin;
	Vector3 normalWorld;
	int i;
	//linear part
	for (i = 0; i < 3; i++) {
		normalWorld = m_calculatedTransformA.basis.get_axis(i);
		memnew_placement(&m_jacLin[i], JacobianEntrySW(
											   A->get_transform().basis.transposed(),
											   B->get_transform().basis.transposed(),
											   m_relPosA,
											   m_relPosB,
											   normalWorld,
											   A->get_inv_inertia(),
											   A->get_inv_mass(),
											   B->get_inv_inertia(),
											   B->get_inv_mass()));
		m_jacLinDiagABInv[i] = real_t(1.) / m_jacLin[i].getDiagonal();
		m_depth[i] = m_delta.dot(normalWorld);
	}
	testLinLimits();
	// angular part
	for (i = 0; i < 3; i++) {
		normalWorld = m_calculatedTransformA.basis.get_axis(i);
		memnew_placement(&m_jacAng[i], JacobianEntrySW(
											   normalWorld,
											   A->get_transform().basis.transposed(),
											   B->get_transform().basis.transposed(),
											   A->get_inv_inertia(),
											   B->get_inv_inertia()));
	}
	testAngLimits();
	Vector3 axisA = m_calculatedTransformA.basis.get_axis(0);
	m_kAngle = real_t(1.0) / (A->compute_angular_impulse_denominator(axisA) + B->compute_angular_impulse_denominator(axisA));
	// clear accumulator for motors
	m_accumulatedLinMotorImpulse = real_t(0.0);
	m_accumulatedAngMotorImpulse = real_t(0.0);

	return true;
} // SliderJointSW::buildJacobianInt()

//-----------------------------------------------------------------------------

void SliderJointSW::solve(real_t p_step) {

	int i;
	// linear
	Vector3 velA = A->get_velocity_in_local_point(m_relPosA);
	Vector3 velB = B->get_velocity_in_local_point(m_relPosB);
	Vector3 vel = velA - velB;
	for (i = 0; i < 3; i++) {
		const Vector3 &normal = m_jacLin[i].m_linearJointAxis;
		real_t rel_vel = normal.dot(vel);
		// calculate positional error
		real_t depth = m_depth[i];
		// get parameters
		real_t softness = (i) ? m_softnessOrthoLin : (m_solveLinLim ? m_softnessLimLin : m_softnessDirLin);
		real_t restitution = (i) ? m_restitutionOrthoLin : (m_solveLinLim ? m_restitutionLimLin : m_restitutionDirLin);
		real_t damping = (i) ? m_dampingOrthoLin : (m_solveLinLim ? m_dampingLimLin : m_dampingDirLin);
		// calcutate and apply impulse
		real_t normalImpulse = softness * (restitution * depth / p_step - damping * rel_vel) * m_jacLinDiagABInv[i];
		Vector3 impulse_vector = normal * normalImpulse;
		A->apply_impulse(m_relPosA, impulse_vector);
		B->apply_impulse(m_relPosB, -impulse_vector);
		if (m_poweredLinMotor && (!i)) { // apply linear motor
			if (m_accumulatedLinMotorImpulse < m_maxLinMotorForce) {
				real_t desiredMotorVel = m_targetLinMotorVelocity;
				real_t motor_relvel = desiredMotorVel + rel_vel;
				normalImpulse = -motor_relvel * m_jacLinDiagABInv[i];
				// clamp accumulated impulse
				real_t new_acc = m_accumulatedLinMotorImpulse + Math::abs(normalImpulse);
				if (new_acc > m_maxLinMotorForce) {
					new_acc = m_maxLinMotorForce;
				}
				real_t del = new_acc - m_accumulatedLinMotorImpulse;
				if (normalImpulse < real_t(0.0)) {
					normalImpulse = -del;
				} else {
					normalImpulse = del;
				}
				m_accumulatedLinMotorImpulse = new_acc;
				// apply clamped impulse
				impulse_vector = normal * normalImpulse;
				A->apply_impulse(m_relPosA, impulse_vector);
				B->apply_impulse(m_relPosB, -impulse_vector);
			}
		}
	}
	// angular
	// get axes in world space
	Vector3 axisA = m_calculatedTransformA.basis.get_axis(0);
	Vector3 axisB = m_calculatedTransformB.basis.get_axis(0);

	const Vector3 &angVelA = A->get_angular_velocity();
	const Vector3 &angVelB = B->get_angular_velocity();

	Vector3 angVelAroundAxisA = axisA * axisA.dot(angVelA);
	Vector3 angVelAroundAxisB = axisB * axisB.dot(angVelB);

	Vector3 angAorthog = angVelA - angVelAroundAxisA;
	Vector3 angBorthog = angVelB - angVelAroundAxisB;
	Vector3 velrelOrthog = angAorthog - angBorthog;
	//solve orthogonal angular velocity correction
	real_t len = velrelOrthog.length();
	if (len > real_t(0.00001)) {
		Vector3 normal = velrelOrthog.normalized();
		real_t denom = A->compute_angular_impulse_denominator(normal) + B->compute_angular_impulse_denominator(normal);
		velrelOrthog *= (real_t(1.) / denom) * m_dampingOrthoAng * m_softnessOrthoAng;
	}
	//solve angular positional correction
	Vector3 angularError = axisA.cross(axisB) * (real_t(1.) / p_step);
	real_t len2 = angularError.length();
	if (len2 > real_t(0.00001)) {
		Vector3 normal2 = angularError.normalized();
		real_t denom2 = A->compute_angular_impulse_denominator(normal2) + B->compute_angular_impulse_denominator(normal2);
		angularError *= (real_t(1.) / denom2) * m_restitutionOrthoAng * m_softnessOrthoAng;
	}
	// apply impulse
	A->apply_torque_impulse(-velrelOrthog + angularError);
	B->apply_torque_impulse(velrelOrthog - angularError);
	real_t impulseMag;
	//solve angular limits
	if (m_solveAngLim) {
		impulseMag = (angVelB - angVelA).dot(axisA) * m_dampingLimAng + m_angDepth * m_restitutionLimAng / p_step;
		impulseMag *= m_kAngle * m_softnessLimAng;
	} else {
		impulseMag = (angVelB - angVelA).dot(axisA) * m_dampingDirAng + m_angDepth * m_restitutionDirAng / p_step;
		impulseMag *= m_kAngle * m_softnessDirAng;
	}
	Vector3 impulse = axisA * impulseMag;
	A->apply_torque_impulse(impulse);
	B->apply_torque_impulse(-impulse);
	//apply angular motor
	if (m_poweredAngMotor) {
		if (m_accumulatedAngMotorImpulse < m_maxAngMotorForce) {
			Vector3 velrel = angVelAroundAxisA - angVelAroundAxisB;
			real_t projRelVel = velrel.dot(axisA);

			real_t desiredMotorVel = m_targetAngMotorVelocity;
			real_t motor_relvel = desiredMotorVel - projRelVel;

			real_t angImpulse = m_kAngle * motor_relvel;
			// clamp accumulated impulse
			real_t new_acc = m_accumulatedAngMotorImpulse + Math::abs(angImpulse);
			if (new_acc > m_maxAngMotorForce) {
				new_acc = m_maxAngMotorForce;
			}
			real_t del = new_acc - m_accumulatedAngMotorImpulse;
			if (angImpulse < real_t(0.0)) {
				angImpulse = -del;
			} else {
				angImpulse = del;
			}
			m_accumulatedAngMotorImpulse = new_acc;
			// apply clamped impulse
			Vector3 motorImp = angImpulse * axisA;
			A->apply_torque_impulse(motorImp);
			B->apply_torque_impulse(-motorImp);
		}
	}
} // SliderJointSW::solveConstraint()

//-----------------------------------------------------------------------------

//-----------------------------------------------------------------------------

void SliderJointSW::calculateTransforms(void) {
	m_calculatedTransformA = A->get_transform() * m_frameInA;
	m_calculatedTransformB = B->get_transform() * m_frameInB;
	m_realPivotAInW = m_calculatedTransformA.origin;
	m_realPivotBInW = m_calculatedTransformB.origin;
	m_sliderAxis = m_calculatedTransformA.basis.get_axis(0); // along X
	m_delta = m_realPivotBInW - m_realPivotAInW;
	m_projPivotInW = m_realPivotAInW + m_sliderAxis.dot(m_delta) * m_sliderAxis;
	Vector3 normalWorld;
	int i;
	//linear part
	for (i = 0; i < 3; i++) {
		normalWorld = m_calculatedTransformA.basis.get_axis(i);
		m_depth[i] = m_delta.dot(normalWorld);
	}
} // SliderJointSW::calculateTransforms()

//-----------------------------------------------------------------------------

void SliderJointSW::testLinLimits(void) {
	m_solveLinLim = false;
	m_linPos = m_depth[0];
	if (m_lowerLinLimit <= m_upperLinLimit) {
		if (m_depth[0] > m_upperLinLimit) {
			m_depth[0] -= m_upperLinLimit;
			m_solveLinLim = true;
		} else if (m_depth[0] < m_lowerLinLimit) {
			m_depth[0] -= m_lowerLinLimit;
			m_solveLinLim = true;
		} else {
			m_depth[0] = real_t(0.);
		}
	} else {
		m_depth[0] = real_t(0.);
	}
} // SliderJointSW::testLinLimits()

//-----------------------------------------------------------------------------

void SliderJointSW::testAngLimits(void) {
	m_angDepth = real_t(0.);
	m_solveAngLim = false;
	if (m_lowerAngLimit <= m_upperAngLimit) {
		const Vector3 axisA0 = m_calculatedTransformA.basis.get_axis(1);
		const Vector3 axisA1 = m_calculatedTransformA.basis.get_axis(2);
		const Vector3 axisB0 = m_calculatedTransformB.basis.get_axis(1);
		real_t rot = atan2fast(axisB0.dot(axisA1), axisB0.dot(axisA0));
		if (rot < m_lowerAngLimit) {
			m_angDepth = rot - m_lowerAngLimit;
			m_solveAngLim = true;
		} else if (rot > m_upperAngLimit) {
			m_angDepth = rot - m_upperAngLimit;
			m_solveAngLim = true;
		}
	}
} // SliderJointSW::testAngLimits()

//-----------------------------------------------------------------------------

Vector3 SliderJointSW::getAncorInA(void) {
	Vector3 ancorInA;
	ancorInA = m_realPivotAInW + (m_lowerLinLimit + m_upperLinLimit) * real_t(0.5) * m_sliderAxis;
	ancorInA = A->get_transform().inverse().xform(ancorInA);
	return ancorInA;
} // SliderJointSW::getAncorInA()

//-----------------------------------------------------------------------------

Vector3 SliderJointSW::getAncorInB(void) {
	Vector3 ancorInB;
	ancorInB = m_frameInB.origin;
	return ancorInB;
} // SliderJointSW::getAncorInB();

void SliderJointSW::set_param(PhysicsServer::SliderJointParam p_param, float p_value) {

	switch (p_param) {
		case PhysicsServer::SLIDER_JOINT_LINEAR_LIMIT_UPPER: m_upperLinLimit = p_value; break;
		case PhysicsServer::SLIDER_JOINT_LINEAR_LIMIT_LOWER: m_lowerLinLimit = p_value; break;
		case PhysicsServer::SLIDER_JOINT_LINEAR_LIMIT_SOFTNESS: m_softnessLimLin = p_value; break;
		case PhysicsServer::SLIDER_JOINT_LINEAR_LIMIT_RESTITUTION: m_restitutionLimLin = p_value; break;
		case PhysicsServer::SLIDER_JOINT_LINEAR_LIMIT_DAMPING: m_dampingLimLin = p_value; break;
		case PhysicsServer::SLIDER_JOINT_LINEAR_MOTION_SOFTNESS: m_softnessDirLin = p_value; break;
		case PhysicsServer::SLIDER_JOINT_LINEAR_MOTION_RESTITUTION: m_restitutionDirLin = p_value; break;
		case PhysicsServer::SLIDER_JOINT_LINEAR_MOTION_DAMPING: m_dampingDirLin = p_value; break;
		case PhysicsServer::SLIDER_JOINT_LINEAR_ORTHOGONAL_SOFTNESS: m_softnessOrthoLin = p_value; break;
		case PhysicsServer::SLIDER_JOINT_LINEAR_ORTHOGONAL_RESTITUTION: m_restitutionOrthoLin = p_value; break;
		case PhysicsServer::SLIDER_JOINT_LINEAR_ORTHOGONAL_DAMPING: m_dampingOrthoLin = p_value; break;

		case PhysicsServer::SLIDER_JOINT_ANGULAR_LIMIT_UPPER: m_upperAngLimit = p_value; break;
		case PhysicsServer::SLIDER_JOINT_ANGULAR_LIMIT_LOWER: m_lowerAngLimit = p_value; break;
		case PhysicsServer::SLIDER_JOINT_ANGULAR_LIMIT_SOFTNESS: m_softnessLimAng = p_value; break;
		case PhysicsServer::SLIDER_JOINT_ANGULAR_LIMIT_RESTITUTION: m_restitutionLimAng = p_value; break;
		case PhysicsServer::SLIDER_JOINT_ANGULAR_LIMIT_DAMPING: m_dampingLimAng = p_value; break;
		case PhysicsServer::SLIDER_JOINT_ANGULAR_MOTION_SOFTNESS: m_softnessDirAng = p_value; break;
		case PhysicsServer::SLIDER_JOINT_ANGULAR_MOTION_RESTITUTION: m_restitutionDirAng = p_value; break;
		case PhysicsServer::SLIDER_JOINT_ANGULAR_MOTION_DAMPING: m_dampingDirAng = p_value; break;
		case PhysicsServer::SLIDER_JOINT_ANGULAR_ORTHOGONAL_SOFTNESS: m_softnessOrthoAng = p_value; break;
		case PhysicsServer::SLIDER_JOINT_ANGULAR_ORTHOGONAL_RESTITUTION: m_restitutionOrthoAng = p_value; break;
		case PhysicsServer::SLIDER_JOINT_ANGULAR_ORTHOGONAL_DAMPING: m_dampingOrthoAng = p_value; break;
	}
}

float SliderJointSW::get_param(PhysicsServer::SliderJointParam p_param) const {

	switch (p_param) {
		case PhysicsServer::SLIDER_JOINT_LINEAR_LIMIT_UPPER: return m_upperLinLimit;
		case PhysicsServer::SLIDER_JOINT_LINEAR_LIMIT_LOWER: return m_lowerLinLimit;
		case PhysicsServer::SLIDER_JOINT_LINEAR_LIMIT_SOFTNESS: return m_softnessLimLin;
		case PhysicsServer::SLIDER_JOINT_LINEAR_LIMIT_RESTITUTION: return m_restitutionLimLin;
		case PhysicsServer::SLIDER_JOINT_LINEAR_LIMIT_DAMPING: return m_dampingLimLin;
		case PhysicsServer::SLIDER_JOINT_LINEAR_MOTION_SOFTNESS: return m_softnessDirLin;
		case PhysicsServer::SLIDER_JOINT_LINEAR_MOTION_RESTITUTION: return m_restitutionDirLin;
		case PhysicsServer::SLIDER_JOINT_LINEAR_MOTION_DAMPING: return m_dampingDirLin;
		case PhysicsServer::SLIDER_JOINT_LINEAR_ORTHOGONAL_SOFTNESS: return m_softnessOrthoLin;
		case PhysicsServer::SLIDER_JOINT_LINEAR_ORTHOGONAL_RESTITUTION: return m_restitutionOrthoLin;
		case PhysicsServer::SLIDER_JOINT_LINEAR_ORTHOGONAL_DAMPING: return m_dampingOrthoLin;

		case PhysicsServer::SLIDER_JOINT_ANGULAR_LIMIT_UPPER: return m_upperAngLimit;
		case PhysicsServer::SLIDER_JOINT_ANGULAR_LIMIT_LOWER: return m_lowerAngLimit;
		case PhysicsServer::SLIDER_JOINT_ANGULAR_LIMIT_SOFTNESS: return m_softnessLimAng;
		case PhysicsServer::SLIDER_JOINT_ANGULAR_LIMIT_RESTITUTION: return m_restitutionLimAng;
		case PhysicsServer::SLIDER_JOINT_ANGULAR_LIMIT_DAMPING: return m_dampingLimAng;
		case PhysicsServer::SLIDER_JOINT_ANGULAR_MOTION_SOFTNESS: return m_softnessDirAng;
		case PhysicsServer::SLIDER_JOINT_ANGULAR_MOTION_RESTITUTION: return m_restitutionDirAng;
		case PhysicsServer::SLIDER_JOINT_ANGULAR_MOTION_DAMPING: return m_dampingDirAng;
		case PhysicsServer::SLIDER_JOINT_ANGULAR_ORTHOGONAL_SOFTNESS: return m_softnessOrthoAng;
		case PhysicsServer::SLIDER_JOINT_ANGULAR_ORTHOGONAL_RESTITUTION: return m_restitutionOrthoAng;
		case PhysicsServer::SLIDER_JOINT_ANGULAR_ORTHOGONAL_DAMPING: return m_dampingOrthoAng;
	}

	return 0;
}