6fdffacb4e
In 3D, collision is disabled between kinematic/static bodies when contacts are generated only to report them. In 2D, this case was already fixed but the code is cleaned to make it easier to follow.
510 lines
16 KiB
C++
510 lines
16 KiB
C++
/*************************************************************************/
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/* body_pair_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) 2007-2021 Juan Linietsky, Ariel Manzur. */
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/* Copyright (c) 2014-2021 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 "body_pair_2d_sw.h"
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#include "collision_solver_2d_sw.h"
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#include "space_2d_sw.h"
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#define POSITION_CORRECTION
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#define ACCUMULATE_IMPULSES
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void BodyPair2DSW::_add_contact(const Vector2 &p_point_A, const Vector2 &p_point_B, void *p_self) {
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BodyPair2DSW *self = (BodyPair2DSW *)p_self;
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self->_contact_added_callback(p_point_A, p_point_B);
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}
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void BodyPair2DSW::_contact_added_callback(const Vector2 &p_point_A, const Vector2 &p_point_B) {
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// check if we already have the contact
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Vector2 local_A = A->get_inv_transform().basis_xform(p_point_A);
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Vector2 local_B = B->get_inv_transform().basis_xform(p_point_B - offset_B);
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int new_index = contact_count;
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ERR_FAIL_COND(new_index >= (MAX_CONTACTS + 1));
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Contact contact;
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contact.acc_normal_impulse = 0;
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contact.acc_bias_impulse = 0;
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contact.acc_tangent_impulse = 0;
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contact.local_A = local_A;
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contact.local_B = local_B;
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contact.reused = true;
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contact.normal = (p_point_A - p_point_B).normalized();
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contact.mass_normal = 0; // will be computed in setup()
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// attempt to determine if the contact will be reused
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real_t recycle_radius_2 = space->get_contact_recycle_radius() * space->get_contact_recycle_radius();
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for (int i = 0; i < contact_count; i++) {
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Contact &c = contacts[i];
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if (
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c.local_A.distance_squared_to(local_A) < (recycle_radius_2) &&
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c.local_B.distance_squared_to(local_B) < (recycle_radius_2)) {
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contact.acc_normal_impulse = c.acc_normal_impulse;
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contact.acc_tangent_impulse = c.acc_tangent_impulse;
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contact.acc_bias_impulse = c.acc_bias_impulse;
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new_index = i;
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break;
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}
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}
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// figure out if the contact amount must be reduced to fit the new contact
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if (new_index == MAX_CONTACTS) {
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// remove the contact with the minimum depth
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int least_deep = -1;
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real_t min_depth = 1e10;
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for (int i = 0; i <= contact_count; i++) {
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Contact &c = (i == contact_count) ? contact : contacts[i];
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Vector2 global_A = A->get_transform().basis_xform(c.local_A);
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Vector2 global_B = B->get_transform().basis_xform(c.local_B) + offset_B;
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Vector2 axis = global_A - global_B;
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real_t depth = axis.dot(c.normal);
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if (depth < min_depth) {
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min_depth = depth;
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least_deep = i;
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}
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}
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ERR_FAIL_COND(least_deep == -1);
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if (least_deep < contact_count) { //replace the last deep contact by the new one
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contacts[least_deep] = contact;
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}
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return;
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}
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contacts[new_index] = contact;
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if (new_index == contact_count) {
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contact_count++;
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}
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}
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void BodyPair2DSW::_validate_contacts() {
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//make sure to erase contacts that are no longer valid
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real_t max_separation = space->get_contact_max_separation();
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real_t max_separation2 = max_separation * max_separation;
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for (int i = 0; i < contact_count; i++) {
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Contact &c = contacts[i];
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bool erase = false;
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if (!c.reused) {
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//was left behind in previous frame
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erase = true;
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} else {
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c.reused = false;
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Vector2 global_A = A->get_transform().basis_xform(c.local_A);
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Vector2 global_B = B->get_transform().basis_xform(c.local_B) + offset_B;
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Vector2 axis = global_A - global_B;
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real_t depth = axis.dot(c.normal);
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if (depth < -max_separation || (global_B + c.normal * depth - global_A).length_squared() > max_separation2) {
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erase = true;
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}
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}
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if (erase) {
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// contact no longer needed, remove
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if ((i + 1) < contact_count) {
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// swap with the last one
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SWAP(contacts[i], contacts[contact_count - 1]);
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}
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i--;
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contact_count--;
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}
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}
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}
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bool BodyPair2DSW::_test_ccd(real_t p_step, Body2DSW *p_A, int p_shape_A, const Transform2D &p_xform_A, Body2DSW *p_B, int p_shape_B, const Transform2D &p_xform_B, bool p_swap_result) {
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Vector2 motion = p_A->get_linear_velocity() * p_step;
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real_t mlen = motion.length();
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if (mlen < CMP_EPSILON) {
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return false;
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}
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Vector2 mnormal = motion / mlen;
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real_t min, max;
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p_A->get_shape(p_shape_A)->project_rangev(mnormal, p_xform_A, min, max);
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bool fast_object = mlen > (max - min) * 0.3; //going too fast in that direction
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if (!fast_object) { //did it move enough in this direction to even attempt raycast? let's say it should move more than 1/3 the size of the object in that axis
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return false;
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}
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//cast a segment from support in motion normal, in the same direction of motion by motion length
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//support is the worst case collision point, so real collision happened before
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int a;
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Vector2 s[2];
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p_A->get_shape(p_shape_A)->get_supports(p_xform_A.basis_xform(mnormal).normalized(), s, a);
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Vector2 from = p_xform_A.xform(s[0]);
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Vector2 to = from + motion;
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Transform2D from_inv = p_xform_B.affine_inverse();
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Vector2 local_from = from_inv.xform(from - mnormal * mlen * 0.1); //start from a little inside the bounding box
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Vector2 local_to = from_inv.xform(to);
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Vector2 rpos, rnorm;
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if (!p_B->get_shape(p_shape_B)->intersect_segment(local_from, local_to, rpos, rnorm)) {
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return false;
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}
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//ray hit something
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Vector2 hitpos = p_xform_B.xform(rpos);
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Vector2 contact_A = to;
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Vector2 contact_B = hitpos;
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//create a contact
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if (p_swap_result) {
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_contact_added_callback(contact_B, contact_A);
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} else {
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_contact_added_callback(contact_A, contact_B);
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}
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return true;
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}
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real_t combine_bounce(Body2DSW *A, Body2DSW *B) {
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return CLAMP(A->get_bounce() + B->get_bounce(), 0, 1);
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}
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real_t combine_friction(Body2DSW *A, Body2DSW *B) {
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return ABS(MIN(A->get_friction(), B->get_friction()));
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}
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bool BodyPair2DSW::setup(real_t p_step) {
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//cannot collide
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if (!A->test_collision_mask(B) || A->has_exception(B->get_self()) || B->has_exception(A->get_self())) {
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collided = false;
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return false;
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}
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bool report_contacts_only = false;
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if ((A->get_mode() <= Physics2DServer::BODY_MODE_KINEMATIC) && (B->get_mode() <= Physics2DServer::BODY_MODE_KINEMATIC)) {
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if ((A->get_max_contacts_reported() > 0) || (B->get_max_contacts_reported() > 0)) {
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report_contacts_only = true;
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} else {
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collided = false;
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return false;
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}
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}
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//use local A coordinates to avoid numerical issues on collision detection
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offset_B = B->get_transform().get_origin() - A->get_transform().get_origin();
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_validate_contacts();
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Vector2 offset_A = A->get_transform().get_origin();
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Transform2D xform_Au = A->get_transform().untranslated();
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Transform2D xform_A = xform_Au * A->get_shape_transform(shape_A);
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Transform2D xform_Bu = B->get_transform();
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xform_Bu.elements[2] -= A->get_transform().get_origin();
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Transform2D xform_B = xform_Bu * B->get_shape_transform(shape_B);
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Shape2DSW *shape_A_ptr = A->get_shape(shape_A);
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Shape2DSW *shape_B_ptr = B->get_shape(shape_B);
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Vector2 motion_A, motion_B;
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if (A->get_continuous_collision_detection_mode() == Physics2DServer::CCD_MODE_CAST_SHAPE) {
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motion_A = A->get_motion();
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}
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if (B->get_continuous_collision_detection_mode() == Physics2DServer::CCD_MODE_CAST_SHAPE) {
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motion_B = B->get_motion();
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}
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bool prev_collided = collided;
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collided = CollisionSolver2DSW::solve(shape_A_ptr, xform_A, motion_A, shape_B_ptr, xform_B, motion_B, _add_contact, this, &sep_axis);
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if (!collided) {
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//test ccd (currently just a raycast)
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if (A->get_continuous_collision_detection_mode() == Physics2DServer::CCD_MODE_CAST_RAY && A->get_mode() > Physics2DServer::BODY_MODE_KINEMATIC) {
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if (_test_ccd(p_step, A, shape_A, xform_A, B, shape_B, xform_B)) {
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collided = true;
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}
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}
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if (B->get_continuous_collision_detection_mode() == Physics2DServer::CCD_MODE_CAST_RAY && B->get_mode() > Physics2DServer::BODY_MODE_KINEMATIC) {
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if (_test_ccd(p_step, B, shape_B, xform_B, A, shape_A, xform_A, true)) {
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collided = true;
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}
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}
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if (!collided) {
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oneway_disabled = false;
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return false;
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}
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}
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if (oneway_disabled) {
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return false;
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}
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if (!prev_collided) {
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if (A->is_shape_set_as_one_way_collision(shape_A)) {
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Vector2 direction = xform_A.get_axis(1).normalized();
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bool valid = false;
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for (int i = 0; i < contact_count; i++) {
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Contact &c = contacts[i];
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if (!c.reused) {
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continue;
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}
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if (c.normal.dot(direction) > -CMP_EPSILON) { //greater (normal inverted)
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continue;
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}
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valid = true;
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break;
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}
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if (!valid) {
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collided = false;
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oneway_disabled = true;
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return false;
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}
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}
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if (B->is_shape_set_as_one_way_collision(shape_B)) {
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Vector2 direction = xform_B.get_axis(1).normalized();
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bool valid = false;
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for (int i = 0; i < contact_count; i++) {
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Contact &c = contacts[i];
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if (!c.reused) {
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continue;
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}
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if (c.normal.dot(direction) < CMP_EPSILON) { //less (normal ok)
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continue;
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}
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valid = true;
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break;
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}
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if (!valid) {
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collided = false;
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oneway_disabled = true;
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return false;
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}
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}
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}
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real_t max_penetration = space->get_contact_max_allowed_penetration();
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real_t bias = 0.3;
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if (shape_A_ptr->get_custom_bias() || shape_B_ptr->get_custom_bias()) {
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if (shape_A_ptr->get_custom_bias() == 0) {
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bias = shape_B_ptr->get_custom_bias();
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} else if (shape_B_ptr->get_custom_bias() == 0) {
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bias = shape_A_ptr->get_custom_bias();
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} else {
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bias = (shape_B_ptr->get_custom_bias() + shape_A_ptr->get_custom_bias()) * 0.5;
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}
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}
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cc = 0;
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real_t inv_dt = 1.0 / p_step;
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bool do_process = false;
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for (int i = 0; i < contact_count; i++) {
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Contact &c = contacts[i];
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c.active = false;
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Vector2 global_A = xform_Au.xform(c.local_A);
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Vector2 global_B = xform_Bu.xform(c.local_B);
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real_t depth = c.normal.dot(global_A - global_B);
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if (depth <= 0 || !c.reused) {
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continue;
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}
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#ifdef DEBUG_ENABLED
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if (space->is_debugging_contacts()) {
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space->add_debug_contact(global_A + offset_A);
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space->add_debug_contact(global_B + offset_A);
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}
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#endif
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c.rA = global_A;
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c.rB = global_B - offset_B;
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if (A->can_report_contacts()) {
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Vector2 crB(-B->get_angular_velocity() * c.rB.y, B->get_angular_velocity() * c.rB.x);
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A->add_contact(global_A + offset_A, -c.normal, depth, shape_A, global_B + offset_A, shape_B, B->get_instance_id(), B->get_self(), crB + B->get_linear_velocity());
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}
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if (B->can_report_contacts()) {
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Vector2 crA(-A->get_angular_velocity() * c.rA.y, A->get_angular_velocity() * c.rA.x);
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B->add_contact(global_B + offset_A, c.normal, depth, shape_B, global_A + offset_A, shape_A, A->get_instance_id(), A->get_self(), crA + A->get_linear_velocity());
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}
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if (report_contacts_only) {
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collided = false;
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continue;
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}
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c.active = true;
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// Precompute normal mass, tangent mass, and bias.
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real_t rnA = c.rA.dot(c.normal);
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real_t rnB = c.rB.dot(c.normal);
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real_t kNormal = A->get_inv_mass() + B->get_inv_mass();
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kNormal += A->get_inv_inertia() * (c.rA.dot(c.rA) - rnA * rnA) + B->get_inv_inertia() * (c.rB.dot(c.rB) - rnB * rnB);
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c.mass_normal = 1.0f / kNormal;
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Vector2 tangent = c.normal.tangent();
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real_t rtA = c.rA.dot(tangent);
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real_t rtB = c.rB.dot(tangent);
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real_t kTangent = A->get_inv_mass() + B->get_inv_mass();
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kTangent += A->get_inv_inertia() * (c.rA.dot(c.rA) - rtA * rtA) + B->get_inv_inertia() * (c.rB.dot(c.rB) - rtB * rtB);
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c.mass_tangent = 1.0f / kTangent;
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c.bias = -bias * inv_dt * MIN(0.0f, -depth + max_penetration);
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c.depth = depth;
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//c.acc_bias_impulse=0;
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#ifdef ACCUMULATE_IMPULSES
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{
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// Apply normal + friction impulse
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Vector2 P = c.acc_normal_impulse * c.normal + c.acc_tangent_impulse * tangent;
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A->apply_impulse(c.rA, -P);
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B->apply_impulse(c.rB, P);
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}
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#endif
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c.bounce = combine_bounce(A, B);
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if (c.bounce) {
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Vector2 crA(-A->get_angular_velocity() * c.rA.y, A->get_angular_velocity() * c.rA.x);
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Vector2 crB(-B->get_angular_velocity() * c.rB.y, B->get_angular_velocity() * c.rB.x);
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Vector2 dv = B->get_linear_velocity() + crB - A->get_linear_velocity() - crA;
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c.bounce = c.bounce * dv.dot(c.normal);
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}
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do_process = true;
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}
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return do_process;
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}
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void BodyPair2DSW::solve(real_t p_step) {
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if (!collided) {
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return;
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}
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for (int i = 0; i < contact_count; ++i) {
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Contact &c = contacts[i];
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cc++;
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if (!c.active) {
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continue;
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}
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// Relative velocity at contact
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Vector2 crA(-A->get_angular_velocity() * c.rA.y, A->get_angular_velocity() * c.rA.x);
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Vector2 crB(-B->get_angular_velocity() * c.rB.y, B->get_angular_velocity() * c.rB.x);
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Vector2 dv = B->get_linear_velocity() + crB - A->get_linear_velocity() - crA;
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Vector2 crbA(-A->get_biased_angular_velocity() * c.rA.y, A->get_biased_angular_velocity() * c.rA.x);
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Vector2 crbB(-B->get_biased_angular_velocity() * c.rB.y, B->get_biased_angular_velocity() * c.rB.x);
|
|
Vector2 dbv = B->get_biased_linear_velocity() + crbB - A->get_biased_linear_velocity() - crbA;
|
|
|
|
real_t vn = dv.dot(c.normal);
|
|
real_t vbn = dbv.dot(c.normal);
|
|
Vector2 tangent = c.normal.tangent();
|
|
real_t vt = dv.dot(tangent);
|
|
|
|
real_t jbn = (c.bias - vbn) * c.mass_normal;
|
|
real_t jbnOld = c.acc_bias_impulse;
|
|
c.acc_bias_impulse = MAX(jbnOld + jbn, 0.0f);
|
|
|
|
Vector2 jb = c.normal * (c.acc_bias_impulse - jbnOld);
|
|
|
|
A->apply_bias_impulse(c.rA, -jb);
|
|
B->apply_bias_impulse(c.rB, jb);
|
|
|
|
real_t jn = -(c.bounce + vn) * c.mass_normal;
|
|
real_t jnOld = c.acc_normal_impulse;
|
|
c.acc_normal_impulse = MAX(jnOld + jn, 0.0f);
|
|
|
|
real_t friction = combine_friction(A, B);
|
|
|
|
real_t jtMax = friction * c.acc_normal_impulse;
|
|
real_t jt = -vt * c.mass_tangent;
|
|
real_t jtOld = c.acc_tangent_impulse;
|
|
c.acc_tangent_impulse = CLAMP(jtOld + jt, -jtMax, jtMax);
|
|
|
|
Vector2 j = c.normal * (c.acc_normal_impulse - jnOld) + tangent * (c.acc_tangent_impulse - jtOld);
|
|
|
|
A->apply_impulse(c.rA, -j);
|
|
B->apply_impulse(c.rB, j);
|
|
}
|
|
}
|
|
|
|
BodyPair2DSW::BodyPair2DSW(Body2DSW *p_A, int p_shape_A, Body2DSW *p_B, int p_shape_B) :
|
|
Constraint2DSW(_arr, 2) {
|
|
A = p_A;
|
|
B = p_B;
|
|
shape_A = p_shape_A;
|
|
shape_B = p_shape_B;
|
|
space = A->get_space();
|
|
A->add_constraint(this, 0);
|
|
B->add_constraint(this, 1);
|
|
contact_count = 0;
|
|
collided = false;
|
|
oneway_disabled = false;
|
|
}
|
|
|
|
BodyPair2DSW::~BodyPair2DSW() {
|
|
A->remove_constraint(this);
|
|
B->remove_constraint(this);
|
|
}
|