459 lines
13 KiB
C++
459 lines
13 KiB
C++
/*************************************************************************/
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/* joints_2d_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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#include "joints_2d_sw.h"
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#include "space_2d_sw.h"
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//based on chipmunk joint constraints
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/* Copyright (c) 2007 Scott Lembcke
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*
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* Permission is hereby granted, free of charge, to any person obtaining a copy
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* of this software and associated documentation files (the "Software"), to deal
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* in the Software without restriction, including without limitation the rights
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* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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* copies of the Software, and to permit persons to whom the Software is
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* furnished to do so, subject to the following conditions:
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*
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* The above copyright notice and this permission notice shall be included in
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* 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, EXPRESS OR
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* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
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* SOFTWARE.
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*/
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static inline real_t k_scalar(Body2DSW *a, Body2DSW *b, const Vector2 &rA, const Vector2 &rB, const Vector2 &n) {
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real_t value = 0;
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{
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value += a->get_inv_mass();
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real_t rcn = rA.cross(n);
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value += a->get_inv_inertia() * rcn * rcn;
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}
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if (b) {
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value += b->get_inv_mass();
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real_t rcn = rB.cross(n);
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value += b->get_inv_inertia() * rcn * rcn;
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}
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return value;
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}
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static inline Vector2
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relative_velocity(Body2DSW *a, Body2DSW *b, Vector2 rA, Vector2 rB) {
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Vector2 sum = a->get_linear_velocity() - rA.tangent() * a->get_angular_velocity();
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if (b)
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return (b->get_linear_velocity() - rB.tangent() * b->get_angular_velocity()) - sum;
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else
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return -sum;
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}
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static inline real_t
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normal_relative_velocity(Body2DSW *a, Body2DSW *b, Vector2 rA, Vector2 rB, Vector2 n) {
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return relative_velocity(a, b, rA, rB).dot(n);
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}
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bool PinJoint2DSW::setup(real_t p_step) {
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Space2DSW *space = A->get_space();
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ERR_FAIL_COND_V(!space, false;)
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rA = A->get_transform().basis_xform(anchor_A);
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rB = B ? B->get_transform().basis_xform(anchor_B) : anchor_B;
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real_t B_inv_mass = B ? B->get_inv_mass() : 0.0;
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Transform2D K1;
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K1[0].x = A->get_inv_mass() + B_inv_mass;
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K1[1].x = 0.0f;
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K1[0].y = 0.0f;
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K1[1].y = A->get_inv_mass() + B_inv_mass;
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Transform2D K2;
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K2[0].x = A->get_inv_inertia() * rA.y * rA.y;
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K2[1].x = -A->get_inv_inertia() * rA.x * rA.y;
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K2[0].y = -A->get_inv_inertia() * rA.x * rA.y;
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K2[1].y = A->get_inv_inertia() * rA.x * rA.x;
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Transform2D K;
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K[0] = K1[0] + K2[0];
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K[1] = K1[1] + K2[1];
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if (B) {
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Transform2D K3;
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K3[0].x = B->get_inv_inertia() * rB.y * rB.y;
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K3[1].x = -B->get_inv_inertia() * rB.x * rB.y;
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K3[0].y = -B->get_inv_inertia() * rB.x * rB.y;
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K3[1].y = B->get_inv_inertia() * rB.x * rB.x;
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K[0] += K3[0];
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K[1] += K3[1];
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}
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K[0].x += softness;
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K[1].y += softness;
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M = K.affine_inverse();
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Vector2 gA = rA + A->get_transform().get_origin();
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Vector2 gB = B ? rB + B->get_transform().get_origin() : rB;
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Vector2 delta = gB - gA;
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bias = delta * -(get_bias() == 0 ? space->get_constraint_bias() : get_bias()) * (1.0 / p_step);
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// apply accumulated impulse
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A->apply_impulse(rA, -P);
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if (B)
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B->apply_impulse(rB, P);
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return true;
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}
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inline Vector2 custom_cross(const Vector2 &p_vec, real_t p_other) {
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return Vector2(p_other * p_vec.y, -p_other * p_vec.x);
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}
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void PinJoint2DSW::solve(real_t p_step) {
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// compute relative velocity
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Vector2 vA = A->get_linear_velocity() - custom_cross(rA, A->get_angular_velocity());
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Vector2 rel_vel;
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if (B)
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rel_vel = B->get_linear_velocity() - custom_cross(rB, B->get_angular_velocity()) - vA;
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else
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rel_vel = -vA;
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Vector2 impulse = M.basis_xform(bias - rel_vel - Vector2(softness, softness) * P);
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A->apply_impulse(rA, -impulse);
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if (B)
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B->apply_impulse(rB, impulse);
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P += impulse;
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}
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void PinJoint2DSW::set_param(Physics2DServer::PinJointParam p_param, real_t p_value) {
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if (p_param == Physics2DServer::PIN_JOINT_SOFTNESS)
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softness = p_value;
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}
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real_t PinJoint2DSW::get_param(Physics2DServer::PinJointParam p_param) const {
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if (p_param == Physics2DServer::PIN_JOINT_SOFTNESS)
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return softness;
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ERR_FAIL_V(0);
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}
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PinJoint2DSW::PinJoint2DSW(const Vector2 &p_pos, Body2DSW *p_body_a, Body2DSW *p_body_b) :
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Joint2DSW(_arr, p_body_b ? 2 : 1) {
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A = p_body_a;
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B = p_body_b;
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anchor_A = p_body_a->get_inv_transform().xform(p_pos);
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anchor_B = p_body_b ? p_body_b->get_inv_transform().xform(p_pos) : p_pos;
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softness = 0;
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p_body_a->add_constraint(this, 0);
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if (p_body_b)
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p_body_b->add_constraint(this, 1);
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}
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PinJoint2DSW::~PinJoint2DSW() {
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if (A)
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A->remove_constraint(this);
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if (B)
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B->remove_constraint(this);
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}
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//////////////////////////////////////////////
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//////////////////////////////////////////////
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//////////////////////////////////////////////
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static inline void
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k_tensor(Body2DSW *a, Body2DSW *b, Vector2 r1, Vector2 r2, Vector2 *k1, Vector2 *k2) {
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// calculate mass matrix
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// If I wasn't lazy and wrote a proper matrix class, this wouldn't be so gross...
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real_t k11, k12, k21, k22;
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real_t m_sum = a->get_inv_mass() + b->get_inv_mass();
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// start with I*m_sum
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k11 = m_sum;
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k12 = 0.0f;
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k21 = 0.0f;
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k22 = m_sum;
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// add the influence from r1
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real_t a_i_inv = a->get_inv_inertia();
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real_t r1xsq = r1.x * r1.x * a_i_inv;
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real_t r1ysq = r1.y * r1.y * a_i_inv;
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real_t r1nxy = -r1.x * r1.y * a_i_inv;
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k11 += r1ysq;
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k12 += r1nxy;
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k21 += r1nxy;
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k22 += r1xsq;
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// add the influnce from r2
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real_t b_i_inv = b->get_inv_inertia();
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real_t r2xsq = r2.x * r2.x * b_i_inv;
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real_t r2ysq = r2.y * r2.y * b_i_inv;
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real_t r2nxy = -r2.x * r2.y * b_i_inv;
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k11 += r2ysq;
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k12 += r2nxy;
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k21 += r2nxy;
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k22 += r2xsq;
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// invert
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real_t determinant = k11 * k22 - k12 * k21;
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ERR_FAIL_COND(determinant == 0.0);
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real_t det_inv = 1.0f / determinant;
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*k1 = Vector2(k22 * det_inv, -k12 * det_inv);
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*k2 = Vector2(-k21 * det_inv, k11 * det_inv);
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}
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static _FORCE_INLINE_ Vector2
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mult_k(const Vector2 &vr, const Vector2 &k1, const Vector2 &k2) {
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return Vector2(vr.dot(k1), vr.dot(k2));
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}
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bool GrooveJoint2DSW::setup(real_t p_step) {
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// calculate endpoints in worldspace
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Vector2 ta = A->get_transform().xform(A_groove_1);
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Vector2 tb = A->get_transform().xform(A_groove_2);
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Space2DSW *space = A->get_space();
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// calculate axis
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Vector2 n = -(tb - ta).tangent().normalized();
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real_t d = ta.dot(n);
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xf_normal = n;
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rB = B->get_transform().basis_xform(B_anchor);
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// calculate tangential distance along the axis of rB
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real_t td = (B->get_transform().get_origin() + rB).cross(n);
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// calculate clamping factor and rB
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if (td <= ta.cross(n)) {
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clamp = 1.0f;
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rA = ta - A->get_transform().get_origin();
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} else if (td >= tb.cross(n)) {
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clamp = -1.0f;
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rA = tb - A->get_transform().get_origin();
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} else {
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clamp = 0.0f;
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//joint->r1 = cpvsub(cpvadd(cpvmult(cpvperp(n), -td), cpvmult(n, d)), a->p);
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rA = ((-n.tangent() * -td) + n * d) - A->get_transform().get_origin();
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}
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// Calculate mass tensor
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k_tensor(A, B, rA, rB, &k1, &k2);
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// compute max impulse
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jn_max = get_max_force() * p_step;
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// calculate bias velocity
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//cpVect delta = cpvsub(cpvadd(b->p, joint->r2), cpvadd(a->p, joint->r1));
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//joint->bias = cpvclamp(cpvmult(delta, -joint->constraint.biasCoef*dt_inv), joint->constraint.maxBias);
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Vector2 delta = (B->get_transform().get_origin() + rB) - (A->get_transform().get_origin() + rA);
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real_t _b = get_bias();
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gbias = (delta * -(_b == 0 ? space->get_constraint_bias() : _b) * (1.0 / p_step)).clamped(get_max_bias());
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// apply accumulated impulse
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A->apply_impulse(rA, -jn_acc);
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B->apply_impulse(rB, jn_acc);
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correct = true;
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return true;
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}
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void GrooveJoint2DSW::solve(real_t p_step) {
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// compute impulse
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Vector2 vr = relative_velocity(A, B, rA, rB);
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Vector2 j = mult_k(gbias - vr, k1, k2);
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Vector2 jOld = jn_acc;
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j += jOld;
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jn_acc = (((clamp * j.cross(xf_normal)) > 0) ? j : j.project(xf_normal)).clamped(jn_max);
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j = jn_acc - jOld;
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A->apply_impulse(rA, -j);
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B->apply_impulse(rB, j);
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}
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GrooveJoint2DSW::GrooveJoint2DSW(const Vector2 &p_a_groove1, const Vector2 &p_a_groove2, const Vector2 &p_b_anchor, Body2DSW *p_body_a, Body2DSW *p_body_b) :
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Joint2DSW(_arr, 2) {
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A = p_body_a;
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B = p_body_b;
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A_groove_1 = A->get_inv_transform().xform(p_a_groove1);
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A_groove_2 = A->get_inv_transform().xform(p_a_groove2);
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B_anchor = B->get_inv_transform().xform(p_b_anchor);
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A_groove_normal = -(A_groove_2 - A_groove_1).normalized().tangent();
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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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GrooveJoint2DSW::~GrooveJoint2DSW() {
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A->remove_constraint(this);
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B->remove_constraint(this);
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}
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//////////////////////////////////////////////
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//////////////////////////////////////////////
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//////////////////////////////////////////////
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bool DampedSpringJoint2DSW::setup(real_t p_step) {
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rA = A->get_transform().basis_xform(anchor_A);
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rB = B->get_transform().basis_xform(anchor_B);
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Vector2 delta = (B->get_transform().get_origin() + rB) - (A->get_transform().get_origin() + rA);
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real_t dist = delta.length();
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if (dist)
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n = delta / dist;
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else
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n = Vector2();
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real_t k = k_scalar(A, B, rA, rB, n);
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n_mass = 1.0f / k;
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target_vrn = 0.0f;
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v_coef = 1.0f - Math::exp(-damping * (p_step)*k);
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// apply spring force
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real_t f_spring = (rest_length - dist) * stiffness;
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Vector2 j = n * f_spring * (p_step);
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A->apply_impulse(rA, -j);
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B->apply_impulse(rB, j);
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return true;
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}
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void DampedSpringJoint2DSW::solve(real_t p_step) {
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// compute relative velocity
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real_t vrn = normal_relative_velocity(A, B, rA, rB, n) - target_vrn;
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// compute velocity loss from drag
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// not 100% certain this is derived correctly, though it makes sense
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real_t v_damp = -vrn * v_coef;
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target_vrn = vrn + v_damp;
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Vector2 j = n * v_damp * n_mass;
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A->apply_impulse(rA, -j);
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B->apply_impulse(rB, j);
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}
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void DampedSpringJoint2DSW::set_param(Physics2DServer::DampedStringParam p_param, real_t p_value) {
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switch (p_param) {
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case Physics2DServer::DAMPED_STRING_REST_LENGTH: {
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rest_length = p_value;
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} break;
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case Physics2DServer::DAMPED_STRING_DAMPING: {
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damping = p_value;
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} break;
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case Physics2DServer::DAMPED_STRING_STIFFNESS: {
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stiffness = p_value;
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} break;
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}
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}
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real_t DampedSpringJoint2DSW::get_param(Physics2DServer::DampedStringParam p_param) const {
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switch (p_param) {
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case Physics2DServer::DAMPED_STRING_REST_LENGTH: {
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return rest_length;
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} break;
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case Physics2DServer::DAMPED_STRING_DAMPING: {
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return damping;
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} break;
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case Physics2DServer::DAMPED_STRING_STIFFNESS: {
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return stiffness;
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} break;
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}
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ERR_FAIL_V(0);
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}
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DampedSpringJoint2DSW::DampedSpringJoint2DSW(const Vector2 &p_anchor_a, const Vector2 &p_anchor_b, Body2DSW *p_body_a, Body2DSW *p_body_b) :
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Joint2DSW(_arr, 2) {
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A = p_body_a;
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B = p_body_b;
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anchor_A = A->get_inv_transform().xform(p_anchor_a);
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anchor_B = B->get_inv_transform().xform(p_anchor_b);
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rest_length = p_anchor_a.distance_to(p_anchor_b);
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stiffness = 20;
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damping = 1.5;
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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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DampedSpringJoint2DSW::~DampedSpringJoint2DSW() {
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A->remove_constraint(this);
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B->remove_constraint(this);
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}
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