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- /*************************************************************************/
- /* cone_twist_joint_sw.cpp */
- /*************************************************************************/
- /* This file is part of: */
- /* GODOT ENGINE */
- /* https://godotengine.org */
- /*************************************************************************/
- /* Copyright (c) 2007-2019 Juan Linietsky, Ariel Manzur. */
- /* Copyright (c) 2014-2019 Godot Engine contributors (cf. AUTHORS.md) */
- /* */
- /* 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 */
- /* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.*/
- /* IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY */
- /* CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, */
- /* TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE */
- /* SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. */
- /*************************************************************************/
- /*
- Adapted to Godot from the Bullet library.
- */
- /*
- Bullet Continuous Collision Detection and Physics Library
- ConeTwistJointSW is Copyright (c) 2007 Starbreeze Studios
- 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.
- Written by: Marcus Hennix
- */
- #include "cone_twist_joint_sw.h"
- static void plane_space(const Vector3 &n, Vector3 &p, Vector3 &q) {
- if (Math::abs(n.z) > 0.707106781186547524400844362) {
- // choose p in y-z plane
- real_t a = n[1] * n[1] + n[2] * n[2];
- real_t k = 1.0 / Math::sqrt(a);
- p = Vector3(0, -n[2] * k, n[1] * k);
- // set q = n x p
- q = Vector3(a * k, -n[0] * p[2], n[0] * p[1]);
- } else {
- // choose p in x-y plane
- real_t a = n.x * n.x + n.y * n.y;
- real_t k = 1.0 / Math::sqrt(a);
- p = Vector3(-n.y * k, n.x * k, 0);
- // set q = n x p
- q = Vector3(-n.z * p.y, n.z * p.x, a * k);
- }
- }
- 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;
- }
- ConeTwistJointSW::ConeTwistJointSW(BodySW *rbA, BodySW *rbB, const Transform &rbAFrame, const Transform &rbBFrame) :
- JointSW(_arr, 2) {
- A = rbA;
- B = rbB;
- m_rbAFrame = rbAFrame;
- m_rbBFrame = rbBFrame;
- m_swingSpan1 = Math_PI / 4.0;
- m_swingSpan2 = Math_PI / 4.0;
- m_twistSpan = Math_PI * 2;
- m_biasFactor = 0.3f;
- m_relaxationFactor = 1.0f;
- m_angularOnly = false;
- m_solveTwistLimit = false;
- m_solveSwingLimit = false;
- A->add_constraint(this, 0);
- B->add_constraint(this, 1);
- m_appliedImpulse = 0;
- }
- bool ConeTwistJointSW::setup(real_t p_timestep) {
- m_appliedImpulse = real_t(0.);
- //set bias, sign, clear accumulator
- m_swingCorrection = real_t(0.);
- m_twistLimitSign = real_t(0.);
- m_solveTwistLimit = false;
- m_solveSwingLimit = false;
- m_accTwistLimitImpulse = real_t(0.);
- m_accSwingLimitImpulse = 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 (relPos.length_squared() > CMP_EPSILON) {
- normal[0] = relPos.normalized();
- } else {
- normal[0] = Vector3(real_t(1.0), 0, 0);
- }
- plane_space(normal[0], normal[1], normal[2]);
- for (int i = 0; i < 3; i++) {
- memnew_placement(&m_jac[i], 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(),
- normal[i],
- A->get_inv_inertia(),
- A->get_inv_mass(),
- B->get_inv_inertia(),
- B->get_inv_mass()));
- }
- }
- Vector3 b1Axis1, b1Axis2, b1Axis3;
- Vector3 b2Axis1, b2Axis2;
- b1Axis1 = A->get_transform().basis.xform(this->m_rbAFrame.basis.get_axis(0));
- b2Axis1 = B->get_transform().basis.xform(this->m_rbBFrame.basis.get_axis(0));
- real_t swing1 = real_t(0.), swing2 = real_t(0.);
- real_t swx = real_t(0.), swy = real_t(0.);
- real_t thresh = real_t(10.);
- real_t fact;
- // Get Frame into world space
- if (m_swingSpan1 >= real_t(0.05f)) {
- b1Axis2 = A->get_transform().basis.xform(this->m_rbAFrame.basis.get_axis(1));
- //swing1 = btAtan2Fast( b2Axis1.dot(b1Axis2),b2Axis1.dot(b1Axis1) );
- swx = b2Axis1.dot(b1Axis1);
- swy = b2Axis1.dot(b1Axis2);
- swing1 = atan2fast(swy, swx);
- fact = (swy * swy + swx * swx) * thresh * thresh;
- fact = fact / (fact + real_t(1.0));
- swing1 *= fact;
- }
- if (m_swingSpan2 >= real_t(0.05f)) {
- b1Axis3 = A->get_transform().basis.xform(this->m_rbAFrame.basis.get_axis(2));
- //swing2 = btAtan2Fast( b2Axis1.dot(b1Axis3),b2Axis1.dot(b1Axis1) );
- swx = b2Axis1.dot(b1Axis1);
- swy = b2Axis1.dot(b1Axis3);
- swing2 = atan2fast(swy, swx);
- fact = (swy * swy + swx * swx) * thresh * thresh;
- fact = fact / (fact + real_t(1.0));
- swing2 *= fact;
- }
- real_t RMaxAngle1Sq = 1.0f / (m_swingSpan1 * m_swingSpan1);
- real_t RMaxAngle2Sq = 1.0f / (m_swingSpan2 * m_swingSpan2);
- real_t EllipseAngle = Math::abs(swing1 * swing1) * RMaxAngle1Sq + Math::abs(swing2 * swing2) * RMaxAngle2Sq;
- if (EllipseAngle > 1.0f) {
- m_swingCorrection = EllipseAngle - 1.0f;
- m_solveSwingLimit = true;
- // Calculate necessary axis & factors
- m_swingAxis = b2Axis1.cross(b1Axis2 * b2Axis1.dot(b1Axis2) + b1Axis3 * b2Axis1.dot(b1Axis3));
- m_swingAxis.normalize();
- real_t swingAxisSign = (b2Axis1.dot(b1Axis1) >= 0.0f) ? 1.0f : -1.0f;
- m_swingAxis *= swingAxisSign;
- m_kSwing = real_t(1.) / (A->compute_angular_impulse_denominator(m_swingAxis) +
- B->compute_angular_impulse_denominator(m_swingAxis));
- }
- // Twist limits
- if (m_twistSpan >= real_t(0.)) {
- Vector3 b2Axis2 = B->get_transform().basis.xform(this->m_rbBFrame.basis.get_axis(1));
- Quat rotationArc = Quat(b2Axis1, b1Axis1);
- Vector3 TwistRef = rotationArc.xform(b2Axis2);
- real_t twist = atan2fast(TwistRef.dot(b1Axis3), TwistRef.dot(b1Axis2));
- real_t lockedFreeFactor = (m_twistSpan > real_t(0.05f)) ? m_limitSoftness : real_t(0.);
- if (twist <= -m_twistSpan * lockedFreeFactor) {
- m_twistCorrection = -(twist + m_twistSpan);
- m_solveTwistLimit = true;
- m_twistAxis = (b2Axis1 + b1Axis1) * 0.5f;
- m_twistAxis.normalize();
- m_twistAxis *= -1.0f;
- m_kTwist = real_t(1.) / (A->compute_angular_impulse_denominator(m_twistAxis) +
- B->compute_angular_impulse_denominator(m_twistAxis));
- } else if (twist > m_twistSpan * lockedFreeFactor) {
- m_twistCorrection = (twist - m_twistSpan);
- m_solveTwistLimit = true;
- m_twistAxis = (b2Axis1 + b1Axis1) * 0.5f;
- m_twistAxis.normalize();
- m_kTwist = real_t(1.) / (A->compute_angular_impulse_denominator(m_twistAxis) +
- B->compute_angular_impulse_denominator(m_twistAxis));
- }
- }
- return true;
- }
- void ConeTwistJointSW::solve(real_t p_timestep) {
- 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_timestep * jacDiagABInv - rel_vel * jacDiagABInv;
- m_appliedImpulse += impulse;
- Vector3 impulse_vector = normal * impulse;
- A->apply_impulse(pivotAInW - A->get_transform().origin, impulse_vector);
- B->apply_impulse(pivotBInW - B->get_transform().origin, -impulse_vector);
- }
- }
- {
- ///solve angular part
- const Vector3 &angVelA = A->get_angular_velocity();
- const Vector3 &angVelB = B->get_angular_velocity();
- // solve swing limit
- if (m_solveSwingLimit) {
- real_t amplitude = ((angVelB - angVelA).dot(m_swingAxis) * m_relaxationFactor * m_relaxationFactor + m_swingCorrection * (real_t(1.) / p_timestep) * m_biasFactor);
- real_t impulseMag = amplitude * m_kSwing;
- // Clamp the accumulated impulse
- real_t temp = m_accSwingLimitImpulse;
- m_accSwingLimitImpulse = MAX(m_accSwingLimitImpulse + impulseMag, real_t(0.0));
- impulseMag = m_accSwingLimitImpulse - temp;
- Vector3 impulse = m_swingAxis * impulseMag;
- A->apply_torque_impulse(impulse);
- B->apply_torque_impulse(-impulse);
- }
- // solve twist limit
- if (m_solveTwistLimit) {
- real_t amplitude = ((angVelB - angVelA).dot(m_twistAxis) * m_relaxationFactor * m_relaxationFactor + m_twistCorrection * (real_t(1.) / p_timestep) * m_biasFactor);
- real_t impulseMag = amplitude * m_kTwist;
- // Clamp the accumulated impulse
- real_t temp = m_accTwistLimitImpulse;
- m_accTwistLimitImpulse = MAX(m_accTwistLimitImpulse + impulseMag, real_t(0.0));
- impulseMag = m_accTwistLimitImpulse - temp;
- Vector3 impulse = m_twistAxis * impulseMag;
- A->apply_torque_impulse(impulse);
- B->apply_torque_impulse(-impulse);
- }
- }
- }
- void ConeTwistJointSW::set_param(PhysicsServer::ConeTwistJointParam p_param, real_t p_value) {
- switch (p_param) {
- case PhysicsServer::CONE_TWIST_JOINT_SWING_SPAN: {
- m_swingSpan1 = p_value;
- m_swingSpan2 = p_value;
- } break;
- case PhysicsServer::CONE_TWIST_JOINT_TWIST_SPAN: {
- m_twistSpan = p_value;
- } break;
- case PhysicsServer::CONE_TWIST_JOINT_BIAS: {
- m_biasFactor = p_value;
- } break;
- case PhysicsServer::CONE_TWIST_JOINT_SOFTNESS: {
- m_limitSoftness = p_value;
- } break;
- case PhysicsServer::CONE_TWIST_JOINT_RELAXATION: {
- m_relaxationFactor = p_value;
- } break;
- case PhysicsServer::CONE_TWIST_MAX: break; // Can't happen, but silences warning
- }
- }
- real_t ConeTwistJointSW::get_param(PhysicsServer::ConeTwistJointParam p_param) const {
- switch (p_param) {
- case PhysicsServer::CONE_TWIST_JOINT_SWING_SPAN: {
- return m_swingSpan1;
- } break;
- case PhysicsServer::CONE_TWIST_JOINT_TWIST_SPAN: {
- return m_twistSpan;
- } break;
- case PhysicsServer::CONE_TWIST_JOINT_BIAS: {
- return m_biasFactor;
- } break;
- case PhysicsServer::CONE_TWIST_JOINT_SOFTNESS: {
- return m_limitSoftness;
- } break;
- case PhysicsServer::CONE_TWIST_JOINT_RELAXATION: {
- return m_relaxationFactor;
- } break;
- case PhysicsServer::CONE_TWIST_MAX: break; // Can't happen, but silences warning
- }
- return 0;
- }
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