virtualx-engine/servers/physics_3d/joints/godot_slider_joint_3d.cpp

/*************************************************************************/
/*  godot_slider_joint_3d.cpp                                            */
/*************************************************************************/
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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.
*/

/*
Added by Roman Ponomarev (rponom@gmail.com)
April 04, 2008

*/

#include "godot_slider_joint_3d.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;
}

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

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

GodotSliderJoint3D::GodotSliderJoint3D(GodotBody3D *rbA, GodotBody3D *rbB, const Transform3D &frameInA, const Transform3D &frameInB) :
		GodotJoint3D(_arr, 2),
		m_frameInA(frameInA),
		m_frameInB(frameInB) {
	A = rbA;
	B = rbB;

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

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

bool GodotSliderJoint3D::setup(real_t p_step) {
	dynamic_A = (A->get_mode() > PhysicsServer3D::BODY_MODE_KINEMATIC);
	dynamic_B = (B->get_mode() > PhysicsServer3D::BODY_MODE_KINEMATIC);

	if (!dynamic_A && !dynamic_B) {
		return false;
	}

	//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_column(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_column(i);
		memnew_placement(
				&m_jacLin[i],
				GodotJacobianEntry3D(
						A->get_principal_inertia_axes().transposed(),
						B->get_principal_inertia_axes().transposed(),
						m_relPosA - A->get_center_of_mass(),
						m_relPosB - B->get_center_of_mass(),
						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_column(i);
		memnew_placement(
				&m_jacAng[i],
				GodotJacobianEntry3D(
						normalWorld,
						A->get_principal_inertia_axes().transposed(),
						B->get_principal_inertia_axes().transposed(),
						A->get_inv_inertia(),
						B->get_inv_inertia()));
	}
	testAngLimits();
	Vector3 axisA = m_calculatedTransformA.basis.get_column(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;
}

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

void GodotSliderJoint3D::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);
		// Calculate and apply impulse.
		real_t normalImpulse = softness * (restitution * depth / p_step - damping * rel_vel) * m_jacLinDiagABInv[i];
		Vector3 impulse_vector = normal * normalImpulse;
		if (dynamic_A) {
			A->apply_impulse(impulse_vector, m_relPosA);
		}
		if (dynamic_B) {
			B->apply_impulse(-impulse_vector, m_relPosB);
		}
		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;
				if (dynamic_A) {
					A->apply_impulse(impulse_vector, m_relPosA);
				}
				if (dynamic_B) {
					B->apply_impulse(-impulse_vector, m_relPosB);
				}
			}
		}
	}
	// angular
	// get axes in world space
	Vector3 axisA = m_calculatedTransformA.basis.get_column(0);
	Vector3 axisB = m_calculatedTransformB.basis.get_column(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
	if (dynamic_A) {
		A->apply_torque_impulse(-velrelOrthog + angularError);
	}
	if (dynamic_B) {
		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;
	if (dynamic_A) {
		A->apply_torque_impulse(impulse);
	}
	if (dynamic_B) {
		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;
			if (dynamic_A) {
				A->apply_torque_impulse(motorImp);
			}
			if (dynamic_B) {
				B->apply_torque_impulse(-motorImp);
			}
		}
	}
}

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

void GodotSliderJoint3D::calculateTransforms() {
	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_column(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_column(i);
		m_depth[i] = m_delta.dot(normalWorld);
	}
}

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

void GodotSliderJoint3D::testLinLimits() {
	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.);
	}
}

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

void GodotSliderJoint3D::testAngLimits() {
	m_angDepth = real_t(0.);
	m_solveAngLim = false;
	if (m_lowerAngLimit <= m_upperAngLimit) {
		const Vector3 axisA0 = m_calculatedTransformA.basis.get_column(1);
		const Vector3 axisA1 = m_calculatedTransformA.basis.get_column(2);
		const Vector3 axisB0 = m_calculatedTransformB.basis.get_column(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;
		}
	}
}

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

Vector3 GodotSliderJoint3D::getAncorInA() {
	Vector3 ancorInA;
	ancorInA = m_realPivotAInW + (m_lowerLinLimit + m_upperLinLimit) * real_t(0.5) * m_sliderAxis;
	ancorInA = A->get_transform().inverse().xform(ancorInA);
	return ancorInA;
}

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

Vector3 GodotSliderJoint3D::getAncorInB() {
	Vector3 ancorInB;
	ancorInB = m_frameInB.origin;
	return ancorInB;
}

void GodotSliderJoint3D::set_param(PhysicsServer3D::SliderJointParam p_param, real_t p_value) {
	switch (p_param) {
		case PhysicsServer3D::SLIDER_JOINT_LINEAR_LIMIT_UPPER:
			m_upperLinLimit = p_value;
			break;
		case PhysicsServer3D::SLIDER_JOINT_LINEAR_LIMIT_LOWER:
			m_lowerLinLimit = p_value;
			break;
		case PhysicsServer3D::SLIDER_JOINT_LINEAR_LIMIT_SOFTNESS:
			m_softnessLimLin = p_value;
			break;
		case PhysicsServer3D::SLIDER_JOINT_LINEAR_LIMIT_RESTITUTION:
			m_restitutionLimLin = p_value;
			break;
		case PhysicsServer3D::SLIDER_JOINT_LINEAR_LIMIT_DAMPING:
			m_dampingLimLin = p_value;
			break;
		case PhysicsServer3D::SLIDER_JOINT_LINEAR_MOTION_SOFTNESS:
			m_softnessDirLin = p_value;
			break;
		case PhysicsServer3D::SLIDER_JOINT_LINEAR_MOTION_RESTITUTION:
			m_restitutionDirLin = p_value;
			break;
		case PhysicsServer3D::SLIDER_JOINT_LINEAR_MOTION_DAMPING:
			m_dampingDirLin = p_value;
			break;
		case PhysicsServer3D::SLIDER_JOINT_LINEAR_ORTHOGONAL_SOFTNESS:
			m_softnessOrthoLin = p_value;
			break;
		case PhysicsServer3D::SLIDER_JOINT_LINEAR_ORTHOGONAL_RESTITUTION:
			m_restitutionOrthoLin = p_value;
			break;
		case PhysicsServer3D::SLIDER_JOINT_LINEAR_ORTHOGONAL_DAMPING:
			m_dampingOrthoLin = p_value;
			break;

		case PhysicsServer3D::SLIDER_JOINT_ANGULAR_LIMIT_UPPER:
			m_upperAngLimit = p_value;
			break;
		case PhysicsServer3D::SLIDER_JOINT_ANGULAR_LIMIT_LOWER:
			m_lowerAngLimit = p_value;
			break;
		case PhysicsServer3D::SLIDER_JOINT_ANGULAR_LIMIT_SOFTNESS:
			m_softnessLimAng = p_value;
			break;
		case PhysicsServer3D::SLIDER_JOINT_ANGULAR_LIMIT_RESTITUTION:
			m_restitutionLimAng = p_value;
			break;
		case PhysicsServer3D::SLIDER_JOINT_ANGULAR_LIMIT_DAMPING:
			m_dampingLimAng = p_value;
			break;
		case PhysicsServer3D::SLIDER_JOINT_ANGULAR_MOTION_SOFTNESS:
			m_softnessDirAng = p_value;
			break;
		case PhysicsServer3D::SLIDER_JOINT_ANGULAR_MOTION_RESTITUTION:
			m_restitutionDirAng = p_value;
			break;
		case PhysicsServer3D::SLIDER_JOINT_ANGULAR_MOTION_DAMPING:
			m_dampingDirAng = p_value;
			break;
		case PhysicsServer3D::SLIDER_JOINT_ANGULAR_ORTHOGONAL_SOFTNESS:
			m_softnessOrthoAng = p_value;
			break;
		case PhysicsServer3D::SLIDER_JOINT_ANGULAR_ORTHOGONAL_RESTITUTION:
			m_restitutionOrthoAng = p_value;
			break;
		case PhysicsServer3D::SLIDER_JOINT_ANGULAR_ORTHOGONAL_DAMPING:
			m_dampingOrthoAng = p_value;
			break;

		case PhysicsServer3D::SLIDER_JOINT_MAX:
			break; // Can't happen, but silences warning
	}
}

real_t GodotSliderJoint3D::get_param(PhysicsServer3D::SliderJointParam p_param) const {
	switch (p_param) {
		case PhysicsServer3D::SLIDER_JOINT_LINEAR_LIMIT_UPPER:
			return m_upperLinLimit;
		case PhysicsServer3D::SLIDER_JOINT_LINEAR_LIMIT_LOWER:
			return m_lowerLinLimit;
		case PhysicsServer3D::SLIDER_JOINT_LINEAR_LIMIT_SOFTNESS:
			return m_softnessLimLin;
		case PhysicsServer3D::SLIDER_JOINT_LINEAR_LIMIT_RESTITUTION:
			return m_restitutionLimLin;
		case PhysicsServer3D::SLIDER_JOINT_LINEAR_LIMIT_DAMPING:
			return m_dampingLimLin;
		case PhysicsServer3D::SLIDER_JOINT_LINEAR_MOTION_SOFTNESS:
			return m_softnessDirLin;
		case PhysicsServer3D::SLIDER_JOINT_LINEAR_MOTION_RESTITUTION:
			return m_restitutionDirLin;
		case PhysicsServer3D::SLIDER_JOINT_LINEAR_MOTION_DAMPING:
			return m_dampingDirLin;
		case PhysicsServer3D::SLIDER_JOINT_LINEAR_ORTHOGONAL_SOFTNESS:
			return m_softnessOrthoLin;
		case PhysicsServer3D::SLIDER_JOINT_LINEAR_ORTHOGONAL_RESTITUTION:
			return m_restitutionOrthoLin;
		case PhysicsServer3D::SLIDER_JOINT_LINEAR_ORTHOGONAL_DAMPING:
			return m_dampingOrthoLin;

		case PhysicsServer3D::SLIDER_JOINT_ANGULAR_LIMIT_UPPER:
			return m_upperAngLimit;
		case PhysicsServer3D::SLIDER_JOINT_ANGULAR_LIMIT_LOWER:
			return m_lowerAngLimit;
		case PhysicsServer3D::SLIDER_JOINT_ANGULAR_LIMIT_SOFTNESS:
			return m_softnessLimAng;
		case PhysicsServer3D::SLIDER_JOINT_ANGULAR_LIMIT_RESTITUTION:
			return m_restitutionLimAng;
		case PhysicsServer3D::SLIDER_JOINT_ANGULAR_LIMIT_DAMPING:
			return m_dampingLimAng;
		case PhysicsServer3D::SLIDER_JOINT_ANGULAR_MOTION_SOFTNESS:
			return m_softnessDirAng;
		case PhysicsServer3D::SLIDER_JOINT_ANGULAR_MOTION_RESTITUTION:
			return m_restitutionDirAng;
		case PhysicsServer3D::SLIDER_JOINT_ANGULAR_MOTION_DAMPING:
			return m_dampingDirAng;
		case PhysicsServer3D::SLIDER_JOINT_ANGULAR_ORTHOGONAL_SOFTNESS:
			return m_softnessOrthoAng;
		case PhysicsServer3D::SLIDER_JOINT_ANGULAR_ORTHOGONAL_RESTITUTION:
			return m_restitutionOrthoAng;
		case PhysicsServer3D::SLIDER_JOINT_ANGULAR_ORTHOGONAL_DAMPING:
			return m_dampingOrthoAng;

		case PhysicsServer3D::SLIDER_JOINT_MAX:
			break; // Can't happen, but silences warning
	}

	return 0;
}