godot/servers/physics/joints/slider_joint_sw.cpp

/*************************************************************************/
/*  slider_joint_sw.cpp                                                  */
/*************************************************************************/
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/*                           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_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_axis(i);
		memnew_placement(&m_jacAng[i],	JacobianEntrySW(
			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_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;

}