452 lines
16 KiB
C++
452 lines
16 KiB
C++
/*************************************************************************/
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/* hinge_joint_sw.cpp */
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/*************************************************************************/
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/* This file is part of: */
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/* GODOT ENGINE */
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/* https://godotengine.org */
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/*************************************************************************/
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/* Copyright (c) 2007-2019 Juan Linietsky, Ariel Manzur. */
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/* Copyright (c) 2014-2019 Godot Engine contributors (cf. AUTHORS.md) */
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/* */
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/* Permission is hereby granted, free of charge, to any person obtaining */
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/* a copy of this software and associated documentation files (the */
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/* "Software"), to deal in the Software without restriction, including */
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/* without limitation the rights to use, copy, modify, merge, publish, */
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/* distribute, sublicense, and/or sell copies of the Software, and to */
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/* permit persons to whom the Software is furnished to do so, subject to */
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/* the following conditions: */
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/* */
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/* The above copyright notice and this permission notice shall be */
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/* included in all copies or substantial portions of the Software. */
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/* */
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/* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, */
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/* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF */
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/* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.*/
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/* IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY */
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/* CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, */
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/* TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE */
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/* SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. */
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/*************************************************************************/
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/*
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Adapted to Godot from the Bullet library.
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*/
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/*
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Bullet Continuous Collision Detection and Physics Library
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Copyright (c) 2003-2006 Erwin Coumans http://continuousphysics.com/Bullet/
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This software is provided 'as-is', without any express or implied warranty.
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In no event will the authors be held liable for any damages arising from the use of this software.
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Permission is granted to anyone to use this software for any purpose,
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including commercial applications, and to alter it and redistribute it freely,
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subject to the following restrictions:
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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.
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2. Altered source versions must be plainly marked as such, and must not be misrepresented as being the original software.
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3. This notice may not be removed or altered from any source distribution.
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*/
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#include "hinge_joint_sw.h"
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static void plane_space(const Vector3 &n, Vector3 &p, Vector3 &q) {
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if (Math::abs(n.z) > 0.707106781186547524400844362) {
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// choose p in y-z plane
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real_t a = n[1] * n[1] + n[2] * n[2];
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real_t k = 1.0 / Math::sqrt(a);
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p = Vector3(0, -n[2] * k, n[1] * k);
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// set q = n x p
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q = Vector3(a * k, -n[0] * p[2], n[0] * p[1]);
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} else {
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// choose p in x-y plane
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real_t a = n.x * n.x + n.y * n.y;
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real_t k = 1.0 / Math::sqrt(a);
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p = Vector3(-n.y * k, n.x * k, 0);
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// set q = n x p
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q = Vector3(-n.z * p.y, n.z * p.x, a * k);
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}
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}
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HingeJointSW::HingeJointSW(BodySW *rbA, BodySW *rbB, const Transform &frameA, const Transform &frameB) :
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JointSW(_arr, 2) {
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A = rbA;
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B = rbB;
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m_rbAFrame = frameA;
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m_rbBFrame = frameB;
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// flip axis
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m_rbBFrame.basis[0][2] *= real_t(-1.);
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m_rbBFrame.basis[1][2] *= real_t(-1.);
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m_rbBFrame.basis[2][2] *= real_t(-1.);
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//start with free
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m_lowerLimit = Math_PI;
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m_upperLimit = -Math_PI;
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m_useLimit = false;
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m_biasFactor = 0.3f;
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m_relaxationFactor = 1.0f;
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m_limitSoftness = 0.9f;
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m_solveLimit = false;
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tau = 0.3;
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m_angularOnly = false;
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m_enableAngularMotor = false;
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A->add_constraint(this, 0);
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B->add_constraint(this, 1);
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}
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HingeJointSW::HingeJointSW(BodySW *rbA, BodySW *rbB, const Vector3 &pivotInA, const Vector3 &pivotInB,
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const Vector3 &axisInA, const Vector3 &axisInB) :
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JointSW(_arr, 2) {
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A = rbA;
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B = rbB;
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m_rbAFrame.origin = pivotInA;
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// since no frame is given, assume this to be zero angle and just pick rb transform axis
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Vector3 rbAxisA1 = rbA->get_transform().basis.get_axis(0);
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Vector3 rbAxisA2;
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real_t projection = axisInA.dot(rbAxisA1);
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if (projection >= 1.0f - CMP_EPSILON) {
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rbAxisA1 = -rbA->get_transform().basis.get_axis(2);
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rbAxisA2 = rbA->get_transform().basis.get_axis(1);
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} else if (projection <= -1.0f + CMP_EPSILON) {
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rbAxisA1 = rbA->get_transform().basis.get_axis(2);
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rbAxisA2 = rbA->get_transform().basis.get_axis(1);
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} else {
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rbAxisA2 = axisInA.cross(rbAxisA1);
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rbAxisA1 = rbAxisA2.cross(axisInA);
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}
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m_rbAFrame.basis = Basis(rbAxisA1.x, rbAxisA2.x, axisInA.x,
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rbAxisA1.y, rbAxisA2.y, axisInA.y,
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rbAxisA1.z, rbAxisA2.z, axisInA.z);
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Quat rotationArc = Quat(axisInA, axisInB);
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Vector3 rbAxisB1 = rotationArc.xform(rbAxisA1);
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Vector3 rbAxisB2 = axisInB.cross(rbAxisB1);
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m_rbBFrame.origin = pivotInB;
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m_rbBFrame.basis = Basis(rbAxisB1.x, rbAxisB2.x, -axisInB.x,
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rbAxisB1.y, rbAxisB2.y, -axisInB.y,
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rbAxisB1.z, rbAxisB2.z, -axisInB.z);
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//start with free
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m_lowerLimit = Math_PI;
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m_upperLimit = -Math_PI;
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m_useLimit = false;
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m_biasFactor = 0.3f;
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m_relaxationFactor = 1.0f;
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m_limitSoftness = 0.9f;
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m_solveLimit = false;
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tau = 0.3;
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m_angularOnly = false;
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m_enableAngularMotor = false;
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A->add_constraint(this, 0);
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B->add_constraint(this, 1);
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}
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bool HingeJointSW::setup(real_t p_step) {
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m_appliedImpulse = real_t(0.);
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if (!m_angularOnly) {
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Vector3 pivotAInW = A->get_transform().xform(m_rbAFrame.origin);
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Vector3 pivotBInW = B->get_transform().xform(m_rbBFrame.origin);
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Vector3 relPos = pivotBInW - pivotAInW;
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Vector3 normal[3];
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if (relPos.length_squared() > CMP_EPSILON) {
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normal[0] = relPos.normalized();
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} else {
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normal[0] = Vector3(real_t(1.0), 0, 0);
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}
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plane_space(normal[0], normal[1], normal[2]);
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for (int i = 0; i < 3; i++) {
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memnew_placement(&m_jac[i], JacobianEntrySW(
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A->get_principal_inertia_axes().transposed(),
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B->get_principal_inertia_axes().transposed(),
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pivotAInW - A->get_transform().origin - A->get_center_of_mass(),
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pivotBInW - B->get_transform().origin - B->get_center_of_mass(),
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normal[i],
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A->get_inv_inertia(),
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A->get_inv_mass(),
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B->get_inv_inertia(),
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B->get_inv_mass()));
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}
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}
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//calculate two perpendicular jointAxis, orthogonal to hingeAxis
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//these two jointAxis require equal angular velocities for both bodies
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//this is unused for now, it's a todo
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Vector3 jointAxis0local;
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Vector3 jointAxis1local;
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plane_space(m_rbAFrame.basis.get_axis(2), jointAxis0local, jointAxis1local);
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A->get_transform().basis.xform(m_rbAFrame.basis.get_axis(2));
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Vector3 jointAxis0 = A->get_transform().basis.xform(jointAxis0local);
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Vector3 jointAxis1 = A->get_transform().basis.xform(jointAxis1local);
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Vector3 hingeAxisWorld = A->get_transform().basis.xform(m_rbAFrame.basis.get_axis(2));
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memnew_placement(&m_jacAng[0], JacobianEntrySW(jointAxis0,
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A->get_principal_inertia_axes().transposed(),
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B->get_principal_inertia_axes().transposed(),
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A->get_inv_inertia(),
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B->get_inv_inertia()));
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memnew_placement(&m_jacAng[1], JacobianEntrySW(jointAxis1,
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A->get_principal_inertia_axes().transposed(),
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B->get_principal_inertia_axes().transposed(),
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A->get_inv_inertia(),
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B->get_inv_inertia()));
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memnew_placement(&m_jacAng[2], JacobianEntrySW(hingeAxisWorld,
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A->get_principal_inertia_axes().transposed(),
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B->get_principal_inertia_axes().transposed(),
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A->get_inv_inertia(),
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B->get_inv_inertia()));
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// Compute limit information
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real_t hingeAngle = get_hinge_angle();
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//set bias, sign, clear accumulator
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m_correction = real_t(0.);
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m_limitSign = real_t(0.);
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m_solveLimit = false;
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m_accLimitImpulse = real_t(0.);
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//if (m_lowerLimit < m_upperLimit)
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if (m_useLimit && m_lowerLimit <= m_upperLimit) {
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//if (hingeAngle <= m_lowerLimit*m_limitSoftness)
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if (hingeAngle <= m_lowerLimit) {
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m_correction = (m_lowerLimit - hingeAngle);
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m_limitSign = 1.0f;
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m_solveLimit = true;
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}
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//else if (hingeAngle >= m_upperLimit*m_limitSoftness)
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else if (hingeAngle >= m_upperLimit) {
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m_correction = m_upperLimit - hingeAngle;
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m_limitSign = -1.0f;
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m_solveLimit = true;
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}
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}
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//Compute K = J*W*J' for hinge axis
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Vector3 axisA = A->get_transform().basis.xform(m_rbAFrame.basis.get_axis(2));
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m_kHinge = 1.0f / (A->compute_angular_impulse_denominator(axisA) +
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B->compute_angular_impulse_denominator(axisA));
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return true;
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}
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void HingeJointSW::solve(real_t p_step) {
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Vector3 pivotAInW = A->get_transform().xform(m_rbAFrame.origin);
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Vector3 pivotBInW = B->get_transform().xform(m_rbBFrame.origin);
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//real_t tau = real_t(0.3);
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//linear part
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if (!m_angularOnly) {
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Vector3 rel_pos1 = pivotAInW - A->get_transform().origin;
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Vector3 rel_pos2 = pivotBInW - B->get_transform().origin;
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Vector3 vel1 = A->get_velocity_in_local_point(rel_pos1);
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Vector3 vel2 = B->get_velocity_in_local_point(rel_pos2);
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Vector3 vel = vel1 - vel2;
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for (int i = 0; i < 3; i++) {
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const Vector3 &normal = m_jac[i].m_linearJointAxis;
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real_t jacDiagABInv = real_t(1.) / m_jac[i].getDiagonal();
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real_t rel_vel;
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rel_vel = normal.dot(vel);
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//positional error (zeroth order error)
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real_t depth = -(pivotAInW - pivotBInW).dot(normal); //this is the error projected on the normal
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real_t impulse = depth * tau / p_step * jacDiagABInv - rel_vel * jacDiagABInv;
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m_appliedImpulse += impulse;
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Vector3 impulse_vector = normal * impulse;
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A->apply_impulse(pivotAInW - A->get_transform().origin, impulse_vector);
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B->apply_impulse(pivotBInW - B->get_transform().origin, -impulse_vector);
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}
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}
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{
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///solve angular part
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// get axes in world space
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Vector3 axisA = A->get_transform().basis.xform(m_rbAFrame.basis.get_axis(2));
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Vector3 axisB = B->get_transform().basis.xform(m_rbBFrame.basis.get_axis(2));
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const Vector3 &angVelA = A->get_angular_velocity();
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const Vector3 &angVelB = B->get_angular_velocity();
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Vector3 angVelAroundHingeAxisA = axisA * axisA.dot(angVelA);
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Vector3 angVelAroundHingeAxisB = axisB * axisB.dot(angVelB);
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Vector3 angAorthog = angVelA - angVelAroundHingeAxisA;
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Vector3 angBorthog = angVelB - angVelAroundHingeAxisB;
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Vector3 velrelOrthog = angAorthog - angBorthog;
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{
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//solve orthogonal angular velocity correction
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real_t relaxation = real_t(1.);
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real_t len = velrelOrthog.length();
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if (len > real_t(0.00001)) {
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Vector3 normal = velrelOrthog.normalized();
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real_t denom = A->compute_angular_impulse_denominator(normal) +
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B->compute_angular_impulse_denominator(normal);
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// scale for mass and relaxation
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velrelOrthog *= (real_t(1.) / denom) * m_relaxationFactor;
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}
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//solve angular positional correction
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Vector3 angularError = -axisA.cross(axisB) * (real_t(1.) / p_step);
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real_t len2 = angularError.length();
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if (len2 > real_t(0.00001)) {
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Vector3 normal2 = angularError.normalized();
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real_t denom2 = A->compute_angular_impulse_denominator(normal2) +
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B->compute_angular_impulse_denominator(normal2);
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angularError *= (real_t(1.) / denom2) * relaxation;
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}
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A->apply_torque_impulse(-velrelOrthog + angularError);
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B->apply_torque_impulse(velrelOrthog - angularError);
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// solve limit
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if (m_solveLimit) {
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real_t amplitude = ((angVelB - angVelA).dot(axisA) * m_relaxationFactor + m_correction * (real_t(1.) / p_step) * m_biasFactor) * m_limitSign;
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real_t impulseMag = amplitude * m_kHinge;
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// Clamp the accumulated impulse
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real_t temp = m_accLimitImpulse;
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m_accLimitImpulse = MAX(m_accLimitImpulse + impulseMag, real_t(0));
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impulseMag = m_accLimitImpulse - temp;
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Vector3 impulse = axisA * impulseMag * m_limitSign;
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A->apply_torque_impulse(impulse);
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B->apply_torque_impulse(-impulse);
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}
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}
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//apply motor
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if (m_enableAngularMotor) {
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//todo: add limits too
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Vector3 angularLimit(0, 0, 0);
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Vector3 velrel = angVelAroundHingeAxisA - angVelAroundHingeAxisB;
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real_t projRelVel = velrel.dot(axisA);
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real_t desiredMotorVel = m_motorTargetVelocity;
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real_t motor_relvel = desiredMotorVel - projRelVel;
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real_t unclippedMotorImpulse = m_kHinge * motor_relvel;
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//todo: should clip against accumulated impulse
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real_t clippedMotorImpulse = unclippedMotorImpulse > m_maxMotorImpulse ? m_maxMotorImpulse : unclippedMotorImpulse;
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clippedMotorImpulse = clippedMotorImpulse < -m_maxMotorImpulse ? -m_maxMotorImpulse : clippedMotorImpulse;
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Vector3 motorImp = clippedMotorImpulse * axisA;
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A->apply_torque_impulse(motorImp + angularLimit);
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B->apply_torque_impulse(-motorImp - angularLimit);
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}
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}
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}
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/*
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void HingeJointSW::updateRHS(real_t timeStep)
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{
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(void)timeStep;
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}
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*/
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static _FORCE_INLINE_ real_t atan2fast(real_t y, real_t x) {
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real_t coeff_1 = Math_PI / 4.0f;
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real_t coeff_2 = 3.0f * coeff_1;
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real_t abs_y = Math::abs(y);
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real_t angle;
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if (x >= 0.0f) {
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real_t r = (x - abs_y) / (x + abs_y);
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angle = coeff_1 - coeff_1 * r;
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} else {
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real_t r = (x + abs_y) / (abs_y - x);
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angle = coeff_2 - coeff_1 * r;
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}
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return (y < 0.0f) ? -angle : angle;
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}
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real_t HingeJointSW::get_hinge_angle() {
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const Vector3 refAxis0 = A->get_transform().basis.xform(m_rbAFrame.basis.get_axis(0));
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const Vector3 refAxis1 = A->get_transform().basis.xform(m_rbAFrame.basis.get_axis(1));
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const Vector3 swingAxis = B->get_transform().basis.xform(m_rbBFrame.basis.get_axis(1));
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return atan2fast(swingAxis.dot(refAxis0), swingAxis.dot(refAxis1));
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}
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void HingeJointSW::set_param(PhysicsServer::HingeJointParam p_param, real_t p_value) {
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switch (p_param) {
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case PhysicsServer::HINGE_JOINT_BIAS: tau = p_value; break;
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case PhysicsServer::HINGE_JOINT_LIMIT_UPPER: m_upperLimit = p_value; break;
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case PhysicsServer::HINGE_JOINT_LIMIT_LOWER: m_lowerLimit = p_value; break;
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case PhysicsServer::HINGE_JOINT_LIMIT_BIAS: m_biasFactor = p_value; break;
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case PhysicsServer::HINGE_JOINT_LIMIT_SOFTNESS: m_limitSoftness = p_value; break;
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case PhysicsServer::HINGE_JOINT_LIMIT_RELAXATION: m_relaxationFactor = p_value; break;
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case PhysicsServer::HINGE_JOINT_MOTOR_TARGET_VELOCITY: m_motorTargetVelocity = p_value; break;
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case PhysicsServer::HINGE_JOINT_MOTOR_MAX_IMPULSE: m_maxMotorImpulse = p_value; break;
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case PhysicsServer::HINGE_JOINT_MAX: break; // Can't happen, but silences warning
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}
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}
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real_t HingeJointSW::get_param(PhysicsServer::HingeJointParam p_param) const {
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switch (p_param) {
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case PhysicsServer::HINGE_JOINT_BIAS: return tau;
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case PhysicsServer::HINGE_JOINT_LIMIT_UPPER: return m_upperLimit;
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case PhysicsServer::HINGE_JOINT_LIMIT_LOWER: return m_lowerLimit;
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case PhysicsServer::HINGE_JOINT_LIMIT_BIAS: return m_biasFactor;
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case PhysicsServer::HINGE_JOINT_LIMIT_SOFTNESS: return m_limitSoftness;
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case PhysicsServer::HINGE_JOINT_LIMIT_RELAXATION: return m_relaxationFactor;
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case PhysicsServer::HINGE_JOINT_MOTOR_TARGET_VELOCITY: return m_motorTargetVelocity;
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case PhysicsServer::HINGE_JOINT_MOTOR_MAX_IMPULSE: return m_maxMotorImpulse;
|
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case PhysicsServer::HINGE_JOINT_MAX: break; // Can't happen, but silences warning
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
void HingeJointSW::set_flag(PhysicsServer::HingeJointFlag p_flag, bool p_value) {
|
|
|
|
switch (p_flag) {
|
|
case PhysicsServer::HINGE_JOINT_FLAG_USE_LIMIT: m_useLimit = p_value; break;
|
|
case PhysicsServer::HINGE_JOINT_FLAG_ENABLE_MOTOR: m_enableAngularMotor = p_value; break;
|
|
case PhysicsServer::HINGE_JOINT_FLAG_MAX: break; // Can't happen, but silences warning
|
|
}
|
|
}
|
|
bool HingeJointSW::get_flag(PhysicsServer::HingeJointFlag p_flag) const {
|
|
|
|
switch (p_flag) {
|
|
case PhysicsServer::HINGE_JOINT_FLAG_USE_LIMIT: return m_useLimit;
|
|
case PhysicsServer::HINGE_JOINT_FLAG_ENABLE_MOTOR: return m_enableAngularMotor;
|
|
case PhysicsServer::HINGE_JOINT_FLAG_MAX: break; // Can't happen, but silences warning
|
|
}
|
|
|
|
return false;
|
|
}
|