godot/servers/physics/joints/cone_twist_joint_sw.cpp

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/*************************************************************************/
/* cone_twist_joint_sw.cpp */
/*************************************************************************/
/* This file is part of: */
/* GODOT ENGINE */
/* http://www.godotengine.org */
/*************************************************************************/
/* Copyright (c) 2007-2017 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 */
/* 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.
See corresponding header file for licensing info.
*/
#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_solveTwistLimit = false;
m_solveSwingLimit = false;
A->add_constraint(this, 0);
B->add_constraint(this, 1);
m_appliedImpulse = 0;
}
bool ConeTwistJointSW::setup(float p_step) {
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_transform().basis.transposed(),
B->get_transform().basis.transposed(),
pivotAInW - A->get_transform().origin,
pivotBInW - B->get_transform().origin,
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 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 / 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.) / 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.) / 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, float 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;
}
}
float 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;
}
return 0;
}