godot/servers/physics_3d/joints/godot_hinge_joint_3d.cpp

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C++

/**************************************************************************/
/* godot_hinge_joint_3d.cpp */
/**************************************************************************/
/* This file is part of: */
/* GODOT ENGINE */
/* https://godotengine.org */
/**************************************************************************/
/* Copyright (c) 2014-present Godot Engine contributors (see AUTHORS.md). */
/* Copyright (c) 2007-2014 Juan Linietsky, Ariel Manzur. */
/* */
/* Permission is hereby granted, free of charge, to any person obtaining */
/* a copy of this software and associated documentation files (the */
/* "Software"), to deal in the Software without restriction, including */
/* without limitation the rights to use, copy, modify, merge, publish, */
/* distribute, sublicense, and/or sell copies of the Software, and to */
/* permit persons to whom the Software is furnished to do so, subject to */
/* the following conditions: */
/* */
/* The above copyright notice and this permission notice shall be */
/* included in all copies or substantial portions of the Software. */
/* */
/* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, */
/* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF */
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/* SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. */
/**************************************************************************/
/*
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.
*/
#include "godot_hinge_joint_3d.h"
GodotHingeJoint3D::GodotHingeJoint3D(GodotBody3D *rbA, GodotBody3D *rbB, const Transform3D &frameA, const Transform3D &frameB) :
GodotJoint3D(_arr, 2) {
A = rbA;
B = rbB;
m_rbAFrame = frameA;
m_rbBFrame = frameB;
// flip axis
m_rbBFrame.basis[0][2] *= real_t(-1.);
m_rbBFrame.basis[1][2] *= real_t(-1.);
m_rbBFrame.basis[2][2] *= real_t(-1.);
A->add_constraint(this, 0);
B->add_constraint(this, 1);
}
GodotHingeJoint3D::GodotHingeJoint3D(GodotBody3D *rbA, GodotBody3D *rbB, const Vector3 &pivotInA, const Vector3 &pivotInB,
const Vector3 &axisInA, const Vector3 &axisInB) :
GodotJoint3D(_arr, 2) {
A = rbA;
B = rbB;
m_rbAFrame.origin = pivotInA;
// since no frame is given, assume this to be zero angle and just pick rb transform axis
Vector3 rbAxisA1 = rbA->get_transform().basis.get_column(0);
Vector3 rbAxisA2;
real_t projection = axisInA.dot(rbAxisA1);
if (projection >= 1.0f - CMP_EPSILON) {
rbAxisA1 = -rbA->get_transform().basis.get_column(2);
rbAxisA2 = rbA->get_transform().basis.get_column(1);
} else if (projection <= -1.0f + CMP_EPSILON) {
rbAxisA1 = rbA->get_transform().basis.get_column(2);
rbAxisA2 = rbA->get_transform().basis.get_column(1);
} else {
rbAxisA2 = axisInA.cross(rbAxisA1);
rbAxisA1 = rbAxisA2.cross(axisInA);
}
m_rbAFrame.basis = Basis(rbAxisA1.x, rbAxisA2.x, axisInA.x,
rbAxisA1.y, rbAxisA2.y, axisInA.y,
rbAxisA1.z, rbAxisA2.z, axisInA.z);
Quaternion rotationArc = Quaternion(axisInA, axisInB);
Vector3 rbAxisB1 = rotationArc.xform(rbAxisA1);
Vector3 rbAxisB2 = axisInB.cross(rbAxisB1);
m_rbBFrame.origin = pivotInB;
m_rbBFrame.basis = Basis(rbAxisB1.x, rbAxisB2.x, -axisInB.x,
rbAxisB1.y, rbAxisB2.y, -axisInB.y,
rbAxisB1.z, rbAxisB2.z, -axisInB.z);
A->add_constraint(this, 0);
B->add_constraint(this, 1);
}
bool GodotHingeJoint3D::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;
}
m_appliedImpulse = real_t(0.);
if (!m_angularOnly) {
Vector3 pivotAInW = A->get_transform().xform(m_rbAFrame.origin);
Vector3 pivotBInW = B->get_transform().xform(m_rbBFrame.origin);
Vector3 relPos = pivotBInW - pivotAInW;
Vector3 normal[3];
if (Math::is_zero_approx(relPos.length_squared())) {
normal[0] = Vector3(real_t(1.0), 0, 0);
} else {
normal[0] = relPos.normalized();
}
plane_space(normal[0], normal[1], normal[2]);
for (int i = 0; i < 3; i++) {
memnew_placement(
&m_jac[i],
GodotJacobianEntry3D(
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(),
normal[i],
A->get_inv_inertia(),
A->get_inv_mass(),
B->get_inv_inertia(),
B->get_inv_mass()));
}
}
//calculate two perpendicular jointAxis, orthogonal to hingeAxis
//these two jointAxis require equal angular velocities for both bodies
//this is unused for now, it's a todo
Vector3 jointAxis0local;
Vector3 jointAxis1local;
plane_space(m_rbAFrame.basis.get_column(2), jointAxis0local, jointAxis1local);
Vector3 jointAxis0 = A->get_transform().basis.xform(jointAxis0local);
Vector3 jointAxis1 = A->get_transform().basis.xform(jointAxis1local);
Vector3 hingeAxisWorld = A->get_transform().basis.xform(m_rbAFrame.basis.get_column(2));
memnew_placement(
&m_jacAng[0],
GodotJacobianEntry3D(
jointAxis0,
A->get_principal_inertia_axes().transposed(),
B->get_principal_inertia_axes().transposed(),
A->get_inv_inertia(),
B->get_inv_inertia()));
memnew_placement(
&m_jacAng[1],
GodotJacobianEntry3D(
jointAxis1,
A->get_principal_inertia_axes().transposed(),
B->get_principal_inertia_axes().transposed(),
A->get_inv_inertia(),
B->get_inv_inertia()));
memnew_placement(
&m_jacAng[2],
GodotJacobianEntry3D(
hingeAxisWorld,
A->get_principal_inertia_axes().transposed(),
B->get_principal_inertia_axes().transposed(),
A->get_inv_inertia(),
B->get_inv_inertia()));
// Compute limit information
real_t hingeAngle = get_hinge_angle();
//set bias, sign, clear accumulator
m_correction = real_t(0.);
m_limitSign = real_t(0.);
m_solveLimit = false;
m_accLimitImpulse = real_t(0.);
if (m_useLimit && m_lowerLimit <= m_upperLimit) {
if (hingeAngle <= m_lowerLimit) {
m_correction = (m_lowerLimit - hingeAngle);
m_limitSign = 1.0f;
m_solveLimit = true;
} else if (hingeAngle >= m_upperLimit) {
m_correction = m_upperLimit - hingeAngle;
m_limitSign = -1.0f;
m_solveLimit = true;
}
}
//Compute K = J*W*J' for hinge axis
Vector3 axisA = A->get_transform().basis.xform(m_rbAFrame.basis.get_column(2));
m_kHinge = 1.0f / (A->compute_angular_impulse_denominator(axisA) + B->compute_angular_impulse_denominator(axisA));
return true;
}
void GodotHingeJoint3D::solve(real_t p_step) {
Vector3 pivotAInW = A->get_transform().xform(m_rbAFrame.origin);
Vector3 pivotBInW = B->get_transform().xform(m_rbBFrame.origin);
//real_t tau = real_t(0.3);
//linear part
if (!m_angularOnly) {
Vector3 rel_pos1 = pivotAInW - A->get_transform().origin;
Vector3 rel_pos2 = pivotBInW - B->get_transform().origin;
Vector3 vel1 = A->get_velocity_in_local_point(rel_pos1);
Vector3 vel2 = B->get_velocity_in_local_point(rel_pos2);
Vector3 vel = vel1 - vel2;
for (int i = 0; i < 3; i++) {
const Vector3 &normal = m_jac[i].m_linearJointAxis;
real_t jacDiagABInv = real_t(1.) / m_jac[i].getDiagonal();
real_t rel_vel;
rel_vel = normal.dot(vel);
//positional error (zeroth order error)
real_t depth = -(pivotAInW - pivotBInW).dot(normal); //this is the error projected on the normal
real_t impulse = depth * tau / p_step * jacDiagABInv - rel_vel * jacDiagABInv;
m_appliedImpulse += impulse;
Vector3 impulse_vector = normal * impulse;
if (dynamic_A) {
A->apply_impulse(impulse_vector, pivotAInW - A->get_transform().origin);
}
if (dynamic_B) {
B->apply_impulse(-impulse_vector, pivotBInW - B->get_transform().origin);
}
}
}
{
///solve angular part
// get axes in world space
Vector3 axisA = A->get_transform().basis.xform(m_rbAFrame.basis.get_column(2));
Vector3 axisB = B->get_transform().basis.xform(m_rbBFrame.basis.get_column(2));
const Vector3 &angVelA = A->get_angular_velocity();
const Vector3 &angVelB = B->get_angular_velocity();
Vector3 angVelAroundHingeAxisA = axisA * axisA.dot(angVelA);
Vector3 angVelAroundHingeAxisB = axisB * axisB.dot(angVelB);
Vector3 angAorthog = angVelA - angVelAroundHingeAxisA;
Vector3 angBorthog = angVelB - angVelAroundHingeAxisB;
Vector3 velrelOrthog = angAorthog - angBorthog;
{
//solve orthogonal angular velocity correction
real_t relaxation = real_t(1.);
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);
// scale for mass and relaxation
velrelOrthog *= (real_t(1.) / denom) * m_relaxationFactor;
}
//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) * relaxation;
}
if (dynamic_A) {
A->apply_torque_impulse(-velrelOrthog + angularError);
}
if (dynamic_B) {
B->apply_torque_impulse(velrelOrthog - angularError);
}
// solve limit
if (m_solveLimit) {
real_t amplitude = ((angVelB - angVelA).dot(axisA) * m_relaxationFactor + m_correction * (real_t(1.) / p_step) * m_biasFactor) * m_limitSign;
real_t impulseMag = amplitude * m_kHinge;
// Clamp the accumulated impulse
real_t temp = m_accLimitImpulse;
m_accLimitImpulse = MAX(m_accLimitImpulse + impulseMag, real_t(0));
impulseMag = m_accLimitImpulse - temp;
Vector3 impulse = axisA * impulseMag * m_limitSign;
if (dynamic_A) {
A->apply_torque_impulse(impulse);
}
if (dynamic_B) {
B->apply_torque_impulse(-impulse);
}
}
}
//apply motor
if (m_enableAngularMotor) {
//todo: add limits too
Vector3 angularLimit(0, 0, 0);
Vector3 velrel = angVelAroundHingeAxisA - angVelAroundHingeAxisB;
real_t projRelVel = velrel.dot(axisA);
real_t desiredMotorVel = m_motorTargetVelocity;
real_t motor_relvel = desiredMotorVel - projRelVel;
real_t unclippedMotorImpulse = m_kHinge * motor_relvel;
//todo: should clip against accumulated impulse
real_t clippedMotorImpulse = unclippedMotorImpulse > m_maxMotorImpulse ? m_maxMotorImpulse : unclippedMotorImpulse;
clippedMotorImpulse = clippedMotorImpulse < -m_maxMotorImpulse ? -m_maxMotorImpulse : clippedMotorImpulse;
Vector3 motorImp = clippedMotorImpulse * axisA;
if (dynamic_A) {
A->apply_torque_impulse(motorImp + angularLimit);
}
if (dynamic_B) {
B->apply_torque_impulse(-motorImp - angularLimit);
}
}
}
}
/*
void HingeJointSW::updateRHS(real_t timeStep)
{
(void)timeStep;
}
*/
real_t GodotHingeJoint3D::get_hinge_angle() {
const Vector3 refAxis0 = A->get_transform().basis.xform(m_rbAFrame.basis.get_column(0));
const Vector3 refAxis1 = A->get_transform().basis.xform(m_rbAFrame.basis.get_column(1));
const Vector3 swingAxis = B->get_transform().basis.xform(m_rbBFrame.basis.get_column(1));
return atan2fast(swingAxis.dot(refAxis0), swingAxis.dot(refAxis1));
}
void GodotHingeJoint3D::set_param(PhysicsServer3D::HingeJointParam p_param, real_t p_value) {
switch (p_param) {
case PhysicsServer3D::HINGE_JOINT_BIAS:
tau = p_value;
break;
case PhysicsServer3D::HINGE_JOINT_LIMIT_UPPER:
m_upperLimit = p_value;
break;
case PhysicsServer3D::HINGE_JOINT_LIMIT_LOWER:
m_lowerLimit = p_value;
break;
case PhysicsServer3D::HINGE_JOINT_LIMIT_BIAS:
m_biasFactor = p_value;
break;
case PhysicsServer3D::HINGE_JOINT_LIMIT_SOFTNESS:
m_limitSoftness = p_value;
break;
case PhysicsServer3D::HINGE_JOINT_LIMIT_RELAXATION:
m_relaxationFactor = p_value;
break;
case PhysicsServer3D::HINGE_JOINT_MOTOR_TARGET_VELOCITY:
m_motorTargetVelocity = p_value;
break;
case PhysicsServer3D::HINGE_JOINT_MOTOR_MAX_IMPULSE:
m_maxMotorImpulse = p_value;
break;
case PhysicsServer3D::HINGE_JOINT_MAX:
break; // Can't happen, but silences warning
}
}
real_t GodotHingeJoint3D::get_param(PhysicsServer3D::HingeJointParam p_param) const {
switch (p_param) {
case PhysicsServer3D::HINGE_JOINT_BIAS:
return tau;
case PhysicsServer3D::HINGE_JOINT_LIMIT_UPPER:
return m_upperLimit;
case PhysicsServer3D::HINGE_JOINT_LIMIT_LOWER:
return m_lowerLimit;
case PhysicsServer3D::HINGE_JOINT_LIMIT_BIAS:
return m_biasFactor;
case PhysicsServer3D::HINGE_JOINT_LIMIT_SOFTNESS:
return m_limitSoftness;
case PhysicsServer3D::HINGE_JOINT_LIMIT_RELAXATION:
return m_relaxationFactor;
case PhysicsServer3D::HINGE_JOINT_MOTOR_TARGET_VELOCITY:
return m_motorTargetVelocity;
case PhysicsServer3D::HINGE_JOINT_MOTOR_MAX_IMPULSE:
return m_maxMotorImpulse;
case PhysicsServer3D::HINGE_JOINT_MAX:
break; // Can't happen, but silences warning
}
return 0;
}
void GodotHingeJoint3D::set_flag(PhysicsServer3D::HingeJointFlag p_flag, bool p_value) {
switch (p_flag) {
case PhysicsServer3D::HINGE_JOINT_FLAG_USE_LIMIT:
m_useLimit = p_value;
break;
case PhysicsServer3D::HINGE_JOINT_FLAG_ENABLE_MOTOR:
m_enableAngularMotor = p_value;
break;
case PhysicsServer3D::HINGE_JOINT_FLAG_MAX:
break; // Can't happen, but silences warning
}
}
bool GodotHingeJoint3D::get_flag(PhysicsServer3D::HingeJointFlag p_flag) const {
switch (p_flag) {
case PhysicsServer3D::HINGE_JOINT_FLAG_USE_LIMIT:
return m_useLimit;
case PhysicsServer3D::HINGE_JOINT_FLAG_ENABLE_MOTOR:
return m_enableAngularMotor;
case PhysicsServer3D::HINGE_JOINT_FLAG_MAX:
break; // Can't happen, but silences warning
}
return false;
}