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godot/servers/physics/body_pair_sw.cpp

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/*************************************************************************/
/* body_pair_sw.cpp */
/*************************************************************************/
/* This file is part of: */
/* GODOT ENGINE */
/* https://godotengine.org */
/*************************************************************************/
/* Copyright (c) 2007-2018 Juan Linietsky, Ariel Manzur. */
/* Copyright (c) 2014-2018 Godot Engine contributors (cf. AUTHORS.md) */
/* */
/* Permission is hereby granted, free of charge, to any person obtaining */
/* a copy of this software and associated documentation files (the */
/* "Software"), to deal in the Software without restriction, including */
/* without limitation the rights to use, copy, modify, merge, publish, */
/* distribute, sublicense, and/or sell copies of the Software, and to */
/* permit persons to whom the Software is furnished to do so, subject to */
/* the following conditions: */
/* */
/* The above copyright notice and this permission notice shall be */
/* included in all copies or substantial portions of the Software. */
/* */
/* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, */
/* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF */
/* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.*/
/* IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY */
/* CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, */
/* TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE */
/* SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. */
/*************************************************************************/
#include "body_pair_sw.h"
#include "collision_solver_sw.h"
#include "os/os.h"
#include "space_sw.h"
/*
#define NO_ACCUMULATE_IMPULSES
#define NO_SPLIT_IMPULSES
#define NO_FRICTION
*/
#define NO_TANGENTIALS
/* BODY PAIR */
//#define ALLOWED_PENETRATION 0.01
#define RELAXATION_TIMESTEPS 3
#define MIN_VELOCITY 0.0001
#define MAX_BIAS_ROTATION (Math_PI / 8)
void BodyPairSW::_contact_added_callback(const Vector3 &p_point_A, const Vector3 &p_point_B, void *p_userdata) {
BodyPairSW *pair = (BodyPairSW *)p_userdata;
pair->contact_added_callback(p_point_A, p_point_B);
}
void BodyPairSW::contact_added_callback(const Vector3 &p_point_A, const Vector3 &p_point_B) {
// check if we already have the contact
//Vector3 local_A = A->get_inv_transform().xform(p_point_A);
//Vector3 local_B = B->get_inv_transform().xform(p_point_B);
Vector3 local_A = A->get_inv_transform().basis.xform(p_point_A);
Vector3 local_B = B->get_inv_transform().basis.xform(p_point_B - offset_B);
int new_index = contact_count;
ERR_FAIL_COND(new_index >= (MAX_CONTACTS + 1));
Contact contact;
contact.acc_normal_impulse = 0;
contact.acc_bias_impulse = 0;
contact.acc_bias_impulse_center_of_mass = 0;
contact.acc_tangent_impulse = Vector3();
contact.local_A = local_A;
contact.local_B = local_B;
contact.normal = (p_point_A - p_point_B).normalized();
contact.mass_normal = 0; // will be computed in setup()
// attempt to determine if the contact will be reused
real_t contact_recycle_radius = space->get_contact_recycle_radius();
for (int i = 0; i < contact_count; i++) {
Contact &c = contacts[i];
if (c.local_A.distance_squared_to(local_A) < (contact_recycle_radius * contact_recycle_radius) &&
c.local_B.distance_squared_to(local_B) < (contact_recycle_radius * contact_recycle_radius)) {
contact.acc_normal_impulse = c.acc_normal_impulse;
contact.acc_bias_impulse = c.acc_bias_impulse;
contact.acc_bias_impulse_center_of_mass = c.acc_bias_impulse_center_of_mass;
contact.acc_tangent_impulse = c.acc_tangent_impulse;
new_index = i;
break;
}
}
// figure out if the contact amount must be reduced to fit the new contact
if (new_index == MAX_CONTACTS) {
// remove the contact with the minimum depth
int least_deep = -1;
real_t min_depth = 1e10;
for (int i = 0; i <= contact_count; i++) {
Contact &c = (i == contact_count) ? contact : contacts[i];
Vector3 global_A = A->get_transform().basis.xform(c.local_A);
Vector3 global_B = B->get_transform().basis.xform(c.local_B) + offset_B;
Vector3 axis = global_A - global_B;
real_t depth = axis.dot(c.normal);
if (depth < min_depth) {
min_depth = depth;
least_deep = i;
}
}
ERR_FAIL_COND(least_deep == -1);
if (least_deep < contact_count) { //replace the last deep contact by the new one
contacts[least_deep] = contact;
}
return;
}
contacts[new_index] = contact;
if (new_index == contact_count) {
contact_count++;
}
}
void BodyPairSW::validate_contacts() {
//make sure to erase contacts that are no longer valid
real_t contact_max_separation = space->get_contact_max_separation();
for (int i = 0; i < contact_count; i++) {
Contact &c = contacts[i];
Vector3 global_A = A->get_transform().basis.xform(c.local_A);
Vector3 global_B = B->get_transform().basis.xform(c.local_B) + offset_B;
Vector3 axis = global_A - global_B;
real_t depth = axis.dot(c.normal);
if (depth < -contact_max_separation || (global_B + c.normal * depth - global_A).length() > contact_max_separation) {
// contact no longer needed, remove
if ((i + 1) < contact_count) {
// swap with the last one
SWAP(contacts[i], contacts[contact_count - 1]);
}
i--;
contact_count--;
}
}
}
bool BodyPairSW::_test_ccd(real_t p_step, BodySW *p_A, int p_shape_A, const Transform &p_xform_A, BodySW *p_B, int p_shape_B, const Transform &p_xform_B) {
Vector3 motion = p_A->get_linear_velocity() * p_step;
real_t mlen = motion.length();
if (mlen < CMP_EPSILON)
return false;
Vector3 mnormal = motion / mlen;
real_t min, max;
p_A->get_shape(p_shape_A)->project_range(mnormal, p_xform_A, min, max);
bool fast_object = mlen > (max - min) * 0.3; //going too fast in that direction
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
return false;
}
//cast a segment from support in motion normal, in the same direction of motion by motion length
//support is the worst case collision point, so real collision happened before
Vector3 s = p_A->get_shape(p_shape_A)->get_support(p_xform_A.basis.xform(mnormal).normalized());
Vector3 from = p_xform_A.xform(s);
Vector3 to = from + motion;
Transform from_inv = p_xform_B.affine_inverse();
Vector3 local_from = from_inv.xform(from - mnormal * mlen * 0.1); //start from a little inside the bounding box
Vector3 local_to = from_inv.xform(to);
Vector3 rpos, rnorm;
if (!p_B->get_shape(p_shape_B)->intersect_segment(local_from, local_to, rpos, rnorm)) {
return false;
}
//shorten the linear velocity so it does not hit, but gets close enough, next frame will hit softly or soft enough
Vector3 hitpos = p_xform_B.xform(rpos);
real_t newlen = hitpos.distance_to(from) - (max - min) * 0.01;
p_A->set_linear_velocity((mnormal * newlen) / p_step);
return true;
}
real_t combine_bounce(BodySW *A, BodySW *B) {
return CLAMP(A->get_bounce() + B->get_bounce(), 0, 1);
}
real_t combine_friction(BodySW *A, BodySW *B) {
return ABS(MIN(A->get_friction(), B->get_friction()));
}
bool BodyPairSW::setup(real_t p_step) {
//cannot collide
if (!A->test_collision_mask(B) || A->has_exception(B->get_self()) || B->has_exception(A->get_self()) || (A->get_mode() <= PhysicsServer::BODY_MODE_KINEMATIC && B->get_mode() <= PhysicsServer::BODY_MODE_KINEMATIC && A->get_max_contacts_reported() == 0 && B->get_max_contacts_reported() == 0)) {
collided = false;
return false;
}
if (A->is_shape_set_as_disabled(shape_A) || B->is_shape_set_as_disabled(shape_B)) {
collided = false;
return false;
}
offset_B = B->get_transform().get_origin() - A->get_transform().get_origin();
validate_contacts();
Vector3 offset_A = A->get_transform().get_origin();
Transform xform_Au = Transform(A->get_transform().basis, Vector3());
Transform xform_A = xform_Au * A->get_shape_transform(shape_A);
Transform xform_Bu = B->get_transform();
xform_Bu.origin -= offset_A;
Transform xform_B = xform_Bu * B->get_shape_transform(shape_B);
ShapeSW *shape_A_ptr = A->get_shape(shape_A);
ShapeSW *shape_B_ptr = B->get_shape(shape_B);
bool collided = CollisionSolverSW::solve_static(shape_A_ptr, xform_A, shape_B_ptr, xform_B, _contact_added_callback, this, &sep_axis);
this->collided = collided;
if (!collided) {
//test ccd (currently just a raycast)
if (A->is_continuous_collision_detection_enabled() && A->get_mode() > PhysicsServer::BODY_MODE_KINEMATIC && B->get_mode() <= PhysicsServer::BODY_MODE_KINEMATIC) {
_test_ccd(p_step, A, shape_A, xform_A, B, shape_B, xform_B);
}
if (B->is_continuous_collision_detection_enabled() && B->get_mode() > PhysicsServer::BODY_MODE_KINEMATIC && A->get_mode() <= PhysicsServer::BODY_MODE_KINEMATIC) {
_test_ccd(p_step, B, shape_B, xform_B, A, shape_A, xform_A);
}
return false;
}
real_t max_penetration = space->get_contact_max_allowed_penetration();
real_t bias = (real_t)0.3;
if (shape_A_ptr->get_custom_bias() || shape_B_ptr->get_custom_bias()) {
if (shape_A_ptr->get_custom_bias() == 0)
bias = shape_B_ptr->get_custom_bias();
else if (shape_B_ptr->get_custom_bias() == 0)
bias = shape_A_ptr->get_custom_bias();
else
bias = (shape_B_ptr->get_custom_bias() + shape_A_ptr->get_custom_bias()) * 0.5;
}
real_t inv_dt = 1.0 / p_step;
for (int i = 0; i < contact_count; i++) {
Contact &c = contacts[i];
c.active = false;
Vector3 global_A = xform_Au.xform(c.local_A);
Vector3 global_B = xform_Bu.xform(c.local_B);
real_t depth = c.normal.dot(global_A - global_B);
if (depth <= 0) {
c.active = false;
continue;
}
c.active = true;
#ifdef DEBUG_ENABLED
if (space->is_debugging_contacts()) {
space->add_debug_contact(global_A + offset_A);
space->add_debug_contact(global_B + offset_A);
}
#endif
c.rA = global_A - A->get_center_of_mass();
c.rB = global_B - B->get_center_of_mass() - offset_B;
// contact query reporting...
if (A->can_report_contacts()) {
Vector3 crA = A->get_angular_velocity().cross(c.rA) + A->get_linear_velocity();
A->add_contact(global_A, -c.normal, depth, shape_A, global_B, shape_B, B->get_instance_id(), B->get_self(), crA);
}
if (B->can_report_contacts()) {
Vector3 crB = B->get_angular_velocity().cross(c.rB) + B->get_linear_velocity();
B->add_contact(global_B, c.normal, depth, shape_B, global_A, shape_A, A->get_instance_id(), A->get_self(), crB);
}
c.active = true;
// Precompute normal mass, tangent mass, and bias.
Vector3 inertia_A = A->get_inv_inertia_tensor().xform(c.rA.cross(c.normal));
Vector3 inertia_B = B->get_inv_inertia_tensor().xform(c.rB.cross(c.normal));
real_t kNormal = A->get_inv_mass() + B->get_inv_mass();
kNormal += c.normal.dot(inertia_A.cross(c.rA)) + c.normal.dot(inertia_B.cross(c.rB));
c.mass_normal = 1.0f / kNormal;
c.bias = -bias * inv_dt * MIN(0.0f, -depth + max_penetration);
c.depth = depth;
Vector3 j_vec = c.normal * c.acc_normal_impulse + c.acc_tangent_impulse;
A->apply_impulse(c.rA + A->get_center_of_mass(), -j_vec);
B->apply_impulse(c.rB + B->get_center_of_mass(), j_vec);
c.acc_bias_impulse = 0;
c.acc_bias_impulse_center_of_mass = 0;
c.bounce = combine_bounce(A, B);
if (c.bounce) {
Vector3 crA = A->get_angular_velocity().cross(c.rA);
Vector3 crB = B->get_angular_velocity().cross(c.rB);
Vector3 dv = B->get_linear_velocity() + crB - A->get_linear_velocity() - crA;
//normal impule
c.bounce = c.bounce * dv.dot(c.normal);
}
}
return true;
}
void BodyPairSW::solve(real_t p_step) {
if (!collided)
return;
for (int i = 0; i < contact_count; i++) {
Contact &c = contacts[i];
if (!c.active)
continue;
c.active = false; //try to deactivate, will activate itself if still needed
//bias impulse
Vector3 crbA = A->get_biased_angular_velocity().cross(c.rA);
Vector3 crbB = B->get_biased_angular_velocity().cross(c.rB);
Vector3 dbv = B->get_biased_linear_velocity() + crbB - A->get_biased_linear_velocity() - crbA;
real_t vbn = dbv.dot(c.normal);
if (Math::abs(-vbn + c.bias) > MIN_VELOCITY) {
real_t jbn = (-vbn + c.bias) * c.mass_normal;
real_t jbnOld = c.acc_bias_impulse;
c.acc_bias_impulse = MAX(jbnOld + jbn, 0.0f);
Vector3 jb = c.normal * (c.acc_bias_impulse - jbnOld);
A->apply_bias_impulse(c.rA + A->get_center_of_mass(), -jb, MAX_BIAS_ROTATION / p_step);
B->apply_bias_impulse(c.rB + B->get_center_of_mass(), jb, MAX_BIAS_ROTATION / p_step);
crbA = A->get_biased_angular_velocity().cross(c.rA);
crbB = B->get_biased_angular_velocity().cross(c.rB);
dbv = B->get_biased_linear_velocity() + crbB - A->get_biased_linear_velocity() - crbA;
vbn = dbv.dot(c.normal);
if (Math::abs(-vbn + c.bias) > MIN_VELOCITY) {
real_t jbn_com = (-vbn + c.bias) / (A->get_inv_mass() + B->get_inv_mass());
real_t jbnOld_com = c.acc_bias_impulse_center_of_mass;
c.acc_bias_impulse_center_of_mass = MAX(jbnOld_com + jbn_com, 0.0f);
Vector3 jb_com = c.normal * (c.acc_bias_impulse_center_of_mass - jbnOld_com);
A->apply_bias_impulse(A->get_center_of_mass(), -jb_com, 0.0f);
B->apply_bias_impulse(B->get_center_of_mass(), jb_com, 0.0f);
}
c.active = true;
}
Vector3 crA = A->get_angular_velocity().cross(c.rA);
Vector3 crB = B->get_angular_velocity().cross(c.rB);
Vector3 dv = B->get_linear_velocity() + crB - A->get_linear_velocity() - crA;
//normal impulse
real_t vn = dv.dot(c.normal);
if (Math::abs(vn) > MIN_VELOCITY) {
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);
Vector3 j = c.normal * (c.acc_normal_impulse - jnOld);
A->apply_impulse(c.rA + A->get_center_of_mass(), -j);
B->apply_impulse(c.rB + B->get_center_of_mass(), j);
c.active = true;
}
//friction impulse
real_t friction = combine_friction(A, B);
Vector3 lvA = A->get_linear_velocity() + A->get_angular_velocity().cross(c.rA);
Vector3 lvB = B->get_linear_velocity() + B->get_angular_velocity().cross(c.rB);
Vector3 dtv = lvB - lvA;
real_t tn = c.normal.dot(dtv);
// tangential velocity
Vector3 tv = dtv - c.normal * tn;
real_t tvl = tv.length();
if (tvl > MIN_VELOCITY) {
tv /= tvl;
Vector3 temp1 = A->get_inv_inertia_tensor().xform(c.rA.cross(tv));
Vector3 temp2 = B->get_inv_inertia_tensor().xform(c.rB.cross(tv));
real_t t = -tvl /
(A->get_inv_mass() + B->get_inv_mass() + tv.dot(temp1.cross(c.rA) + temp2.cross(c.rB)));
Vector3 jt = t * tv;
Vector3 jtOld = c.acc_tangent_impulse;
c.acc_tangent_impulse += jt;
real_t fi_len = c.acc_tangent_impulse.length();
real_t jtMax = c.acc_normal_impulse * friction;
if (fi_len > CMP_EPSILON && fi_len > jtMax) {
c.acc_tangent_impulse *= jtMax / fi_len;
}
jt = c.acc_tangent_impulse - jtOld;
A->apply_impulse(c.rA + A->get_center_of_mass(), -jt);
B->apply_impulse(c.rB + B->get_center_of_mass(), jt);
c.active = true;
}
}
}
BodyPairSW::BodyPairSW(BodySW *p_A, int p_shape_A, BodySW *p_B, int p_shape_B) :
ConstraintSW(_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;
}
BodyPairSW::~BodyPairSW() {
A->remove_constraint(this);
B->remove_constraint(this);
}
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