godot/servers/physics_2d/body_pair_2d_sw.cpp
2017-04-08 00:11:42 +02:00

518 lines
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/*************************************************************************/
/* body_pair_2d_sw.cpp */
/*************************************************************************/
/* This file is part of: */
/* GODOT ENGINE */
/* http://www.godotengine.org */
/*************************************************************************/
/* Copyright (c) 2007-2017 Juan Linietsky, Ariel Manzur. */
/* Copyright (c) 2014-2017 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 */
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/* 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 */
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/* SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. */
/*************************************************************************/
#include "body_pair_2d_sw.h"
#include "collision_solver_2d_sw.h"
#include "space_2d_sw.h"
#define POSITION_CORRECTION
#define ACCUMULATE_IMPULSES
void BodyPair2DSW::_add_contact(const Vector2 &p_point_A, const Vector2 &p_point_B, void *p_self) {
BodyPair2DSW *self = (BodyPair2DSW *)p_self;
self->_contact_added_callback(p_point_A, p_point_B);
}
void BodyPair2DSW::_contact_added_callback(const Vector2 &p_point_A, const Vector2 &p_point_B) {
// check if we already have the contact
Vector2 local_A = A->get_inv_transform().basis_xform(p_point_A);
Vector2 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_tangent_impulse = 0;
contact.local_A = local_A;
contact.local_B = local_B;
contact.reused = true;
contact.normal = (p_point_A - p_point_B).normalized();
// attempt to determine if the contact will be reused
real_t recycle_radius_2 = space->get_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) < (recycle_radius_2) &&
c.local_B.distance_squared_to(local_B) < (recycle_radius_2)) {
contact.acc_normal_impulse = c.acc_normal_impulse;
contact.acc_tangent_impulse = c.acc_tangent_impulse;
contact.acc_bias_impulse = c.acc_bias_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];
Vector2 global_A = A->get_transform().basis_xform(c.local_A);
Vector2 global_B = B->get_transform().basis_xform(c.local_B) + offset_B;
Vector2 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 BodyPair2DSW::_validate_contacts() {
//make sure to erase contacts that are no longer valid
real_t max_separation = space->get_contact_max_separation();
real_t max_separation2 = max_separation * max_separation;
for (int i = 0; i < contact_count; i++) {
Contact &c = contacts[i];
bool erase = false;
if (c.reused == false) {
//was left behind in previous frame
erase = true;
} else {
c.reused = false;
Vector2 global_A = A->get_transform().basis_xform(c.local_A);
Vector2 global_B = B->get_transform().basis_xform(c.local_B) + offset_B;
Vector2 axis = global_A - global_B;
real_t depth = axis.dot(c.normal);
if (depth < -max_separation || (global_B + c.normal * depth - global_A).length_squared() > max_separation2) {
erase = true;
}
}
if (erase) {
// 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 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) {
Vector2 motion = p_A->get_linear_velocity() * p_step;
real_t mlen = motion.length();
if (mlen < CMP_EPSILON)
return false;
Vector2 mnormal = motion / mlen;
real_t min, max;
p_A->get_shape(p_shape_A)->project_rangev(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
int a;
Vector2 s[2];
p_A->get_shape(p_shape_A)->get_supports(p_xform_A.basis_xform(mnormal).normalized(), s, a);
Vector2 from = p_xform_A.xform(s[0]);
Vector2 to = from + motion;
Transform2D from_inv = p_xform_B.affine_inverse();
Vector2 local_from = from_inv.xform(from - mnormal * mlen * 0.1); //start from a little inside the bounding box
Vector2 local_to = from_inv.xform(to);
Vector2 rpos, rnorm;
if (!p_B->get_shape(p_shape_B)->intersect_segment(local_from, local_to, rpos, rnorm))
return false;
//ray hit something
Vector2 hitpos = p_xform_B.xform(rpos);
Vector2 contact_A = to;
Vector2 contact_B = hitpos;
//create a contact
if (p_swap_result)
_contact_added_callback(contact_B, contact_A);
else
_contact_added_callback(contact_A, contact_B);
return true;
}
bool BodyPair2DSW::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() <= Physics2DServer::BODY_MODE_KINEMATIC && B->get_mode() <= Physics2DServer::BODY_MODE_KINEMATIC && A->get_max_contacts_reported() == 0 && B->get_max_contacts_reported() == 0)) {
collided = false;
return false;
}
//use local A coordinates to avoid numerical issues on collision detection
offset_B = B->get_transform().get_origin() - A->get_transform().get_origin();
_validate_contacts();
Vector2 offset_A = A->get_transform().get_origin();
Transform2D xform_Au = A->get_transform().untranslated();
Transform2D xform_A = xform_Au * A->get_shape_transform(shape_A);
Transform2D xform_Bu = B->get_transform();
xform_Bu.elements[2] -= A->get_transform().get_origin();
Transform2D xform_B = xform_Bu * B->get_shape_transform(shape_B);
Shape2DSW *shape_A_ptr = A->get_shape(shape_A);
Shape2DSW *shape_B_ptr = B->get_shape(shape_B);
Vector2 motion_A, motion_B;
if (A->get_continuous_collision_detection_mode() == Physics2DServer::CCD_MODE_CAST_SHAPE) {
motion_A = A->get_motion();
}
if (B->get_continuous_collision_detection_mode() == Physics2DServer::CCD_MODE_CAST_SHAPE) {
motion_B = B->get_motion();
}
//faster to set than to check..
//bool prev_collided=collided;
collided = CollisionSolver2DSW::solve(shape_A_ptr, xform_A, motion_A, shape_B_ptr, xform_B, motion_B, _add_contact, this, &sep_axis);
if (!collided) {
//test ccd (currently just a raycast)
if (A->get_continuous_collision_detection_mode() == Physics2DServer::CCD_MODE_CAST_RAY && A->get_mode() > Physics2DServer::BODY_MODE_KINEMATIC) {
if (_test_ccd(p_step, A, shape_A, xform_A, B, shape_B, xform_B))
collided = true;
}
if (B->get_continuous_collision_detection_mode() == Physics2DServer::CCD_MODE_CAST_RAY && B->get_mode() > Physics2DServer::BODY_MODE_KINEMATIC) {
if (_test_ccd(p_step, B, shape_B, xform_B, A, shape_A, xform_A, true))
collided = true;
}
if (!collided) {
oneway_disabled = false;
return false;
}
}
if (oneway_disabled)
return false;
//if (!prev_collided) {
{
if (A->is_using_one_way_collision()) {
Vector2 direction = A->get_one_way_collision_direction();
bool valid = false;
if (B->get_linear_velocity().dot(direction) >= 0) {
for (int i = 0; i < contact_count; i++) {
Contact &c = contacts[i];
if (!c.reused)
continue;
if (c.normal.dot(direction) < 0)
continue;
valid = true;
break;
}
}
if (!valid) {
collided = false;
oneway_disabled = true;
return false;
}
}
if (B->is_using_one_way_collision()) {
Vector2 direction = B->get_one_way_collision_direction();
bool valid = false;
if (A->get_linear_velocity().dot(direction) >= 0) {
for (int i = 0; i < contact_count; i++) {
Contact &c = contacts[i];
if (!c.reused)
continue;
if (c.normal.dot(direction) < 0)
continue;
valid = true;
break;
}
}
if (!valid) {
collided = false;
oneway_disabled = true;
return false;
}
}
}
real_t max_penetration = space->get_contact_max_allowed_penetration();
real_t bias = 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;
}
cc = 0;
real_t inv_dt = 1.0 / p_step;
bool do_process = false;
for (int i = 0; i < contact_count; i++) {
Contact &c = contacts[i];
Vector2 global_A = xform_Au.xform(c.local_A);
Vector2 global_B = xform_Bu.xform(c.local_B);
real_t depth = c.normal.dot(global_A - global_B);
if (depth <= 0 || !c.reused) {
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
int gather_A = A->can_report_contacts();
int gather_B = B->can_report_contacts();
c.rA = global_A;
c.rB = global_B - offset_B;
if (gather_A | gather_B) {
//Vector2 crB( -B->get_angular_velocity() * c.rB.y, B->get_angular_velocity() * c.rB.x );
global_A += offset_A;
global_B += offset_A;
if (gather_A) {
Vector2 crB(-B->get_angular_velocity() * c.rB.y, B->get_angular_velocity() * c.rB.x);
A->add_contact(global_A, -c.normal, depth, shape_A, global_B, shape_B, B->get_instance_id(), B->get_self(), crB + B->get_linear_velocity());
}
if (gather_B) {
Vector2 crA(-A->get_angular_velocity() * c.rA.y, A->get_angular_velocity() * c.rA.x);
B->add_contact(global_B, c.normal, depth, shape_B, global_A, shape_A, A->get_instance_id(), A->get_self(), crA + A->get_linear_velocity());
}
}
if (A->is_shape_set_as_trigger(shape_A) || B->is_shape_set_as_trigger(shape_B) || (A->get_mode() <= Physics2DServer::BODY_MODE_KINEMATIC && B->get_mode() <= Physics2DServer::BODY_MODE_KINEMATIC)) {
c.active = false;
collided = false;
continue;
}
// Precompute normal mass, tangent mass, and bias.
real_t rnA = c.rA.dot(c.normal);
real_t rnB = c.rB.dot(c.normal);
real_t kNormal = A->get_inv_mass() + B->get_inv_mass();
kNormal += A->get_inv_inertia() * (c.rA.dot(c.rA) - rnA * rnA) + B->get_inv_inertia() * (c.rB.dot(c.rB) - rnB * rnB);
c.mass_normal = 1.0f / kNormal;
Vector2 tangent = c.normal.tangent();
real_t rtA = c.rA.dot(tangent);
real_t rtB = c.rB.dot(tangent);
real_t kTangent = A->get_inv_mass() + B->get_inv_mass();
kTangent += A->get_inv_inertia() * (c.rA.dot(c.rA) - rtA * rtA) + B->get_inv_inertia() * (c.rB.dot(c.rB) - rtB * rtB);
c.mass_tangent = 1.0f / kTangent;
c.bias = -bias * inv_dt * MIN(0.0f, -depth + max_penetration);
c.depth = depth;
//c.acc_bias_impulse=0;
#ifdef ACCUMULATE_IMPULSES
{
// Apply normal + friction impulse
Vector2 P = c.acc_normal_impulse * c.normal + c.acc_tangent_impulse * tangent;
A->apply_impulse(c.rA, -P);
B->apply_impulse(c.rB, P);
}
#endif
c.bounce = MAX(A->get_bounce(), B->get_bounce());
if (c.bounce) {
Vector2 crA(-A->get_angular_velocity() * c.rA.y, A->get_angular_velocity() * c.rA.x);
Vector2 crB(-B->get_angular_velocity() * c.rB.y, B->get_angular_velocity() * c.rB.x);
Vector2 dv = B->get_linear_velocity() + crB - A->get_linear_velocity() - crA;
c.bounce = c.bounce * dv.dot(c.normal);
}
do_process = true;
}
return do_process;
}
void BodyPair2DSW::solve(real_t p_step) {
if (!collided)
return;
for (int i = 0; i < contact_count; ++i) {
Contact &c = contacts[i];
cc++;
if (!c.active)
continue;
// Relative velocity at contact
Vector2 crA(-A->get_angular_velocity() * c.rA.y, A->get_angular_velocity() * c.rA.x);
Vector2 crB(-B->get_angular_velocity() * c.rB.y, B->get_angular_velocity() * c.rB.x);
Vector2 dv = B->get_linear_velocity() + crB - A->get_linear_velocity() - crA;
Vector2 crbA(-A->get_biased_angular_velocity() * c.rA.y, A->get_biased_angular_velocity() * c.rA.x);
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 = A->get_friction() * B->get_friction();
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);
}