virtualx-engine/servers/physics_3d/godot_body_pair_3d.h
PouleyKetchoupp 5cbc7149a1 Improve RigidDynamicBody contacts in 2D and 3D
Changed the algorithm for solving contacts to keep previous contacts as
long as they are under the max separation threshold to keep contact
impulses more consistent and contacts more stable.

Also made 2D consistent with 3D and changed some default parameters:
-Contact bias is now 0.8 instead of 0.3 to avoid springy contacts
-Solver iterations are 16 instead of 8 by default for better stability

Performance considerations:
Tested with stress tests that include lots of contacts from overlapping
bodies.
3D: There's no measurable difference in performance.
2D: Performance is a bit lower (close to 10% slower in extreme cases)
The benefit for 2D physics to be much more stable outweighs the slight
decrease in performance, and this could be alleviated by changing the
algorithm to use jacobians for contact solving to help with cache
efficiency and memory allocations.
2021-12-03 10:40:15 -07:00

145 lines
5.4 KiB
C++

/*************************************************************************/
/* godot_body_pair_3d.h */
/*************************************************************************/
/* This file is part of: */
/* GODOT ENGINE */
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/* Copyright (c) 2007-2021 Juan Linietsky, Ariel Manzur. */
/* Copyright (c) 2014-2021 Godot Engine contributors (cf. AUTHORS.md). */
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#ifndef GODOT_BODY_PAIR_3D_H
#define GODOT_BODY_PAIR_3D_H
#include "godot_body_3d.h"
#include "godot_constraint_3d.h"
#include "godot_soft_body_3d.h"
#include "core/templates/local_vector.h"
class GodotBodyContact3D : public GodotConstraint3D {
protected:
struct Contact {
Vector3 position;
Vector3 normal;
int index_A = 0, index_B = 0;
Vector3 local_A, local_B;
real_t acc_normal_impulse = 0.0; // accumulated normal impulse (Pn)
Vector3 acc_tangent_impulse; // accumulated tangent impulse (Pt)
real_t acc_bias_impulse = 0.0; // accumulated normal impulse for position bias (Pnb)
real_t acc_bias_impulse_center_of_mass = 0.0; // accumulated normal impulse for position bias applied to com
real_t mass_normal = 0.0;
real_t bias = 0.0;
real_t bounce = 0.0;
real_t depth = 0.0;
bool active = false;
bool used = false;
Vector3 rA, rB; // Offset in world orientation with respect to center of mass
};
Vector3 sep_axis;
bool collided = false;
GodotSpace3D *space = nullptr;
GodotBodyContact3D(GodotBody3D **p_body_ptr = nullptr, int p_body_count = 0) :
GodotConstraint3D(p_body_ptr, p_body_count) {
}
};
class GodotBodyPair3D : public GodotBodyContact3D {
enum {
MAX_CONTACTS = 4
};
union {
struct {
GodotBody3D *A;
GodotBody3D *B;
};
GodotBody3D *_arr[2] = { nullptr, nullptr };
};
int shape_A = 0;
int shape_B = 0;
bool collide_A = false;
bool collide_B = false;
bool report_contacts_only = false;
Vector3 offset_B; //use local A coordinates to avoid numerical issues on collision detection
Contact contacts[MAX_CONTACTS];
int contact_count = 0;
static void _contact_added_callback(const Vector3 &p_point_A, int p_index_A, const Vector3 &p_point_B, int p_index_B, void *p_userdata);
void contact_added_callback(const Vector3 &p_point_A, int p_index_A, const Vector3 &p_point_B, int p_index_B);
void validate_contacts();
bool _test_ccd(real_t p_step, GodotBody3D *p_A, int p_shape_A, const Transform3D &p_xform_A, GodotBody3D *p_B, int p_shape_B, const Transform3D &p_xform_B);
public:
virtual bool setup(real_t p_step) override;
virtual bool pre_solve(real_t p_step) override;
virtual void solve(real_t p_step) override;
GodotBodyPair3D(GodotBody3D *p_A, int p_shape_A, GodotBody3D *p_B, int p_shape_B);
~GodotBodyPair3D();
};
class GodotBodySoftBodyPair3D : public GodotBodyContact3D {
GodotBody3D *body = nullptr;
GodotSoftBody3D *soft_body = nullptr;
int body_shape = 0;
bool body_collides = false;
bool soft_body_collides = false;
bool report_contacts_only = false;
LocalVector<Contact> contacts;
static void _contact_added_callback(const Vector3 &p_point_A, int p_index_A, const Vector3 &p_point_B, int p_index_B, void *p_userdata);
void contact_added_callback(const Vector3 &p_point_A, int p_index_A, const Vector3 &p_point_B, int p_index_B);
void validate_contacts();
public:
virtual bool setup(real_t p_step) override;
virtual bool pre_solve(real_t p_step) override;
virtual void solve(real_t p_step) override;
virtual GodotSoftBody3D *get_soft_body_ptr(int p_index) const override { return soft_body; }
virtual int get_soft_body_count() const override { return 1; }
GodotBodySoftBodyPair3D(GodotBody3D *p_A, int p_shape_A, GodotSoftBody3D *p_B);
~GodotBodySoftBodyPair3D();
};
#endif // GODOT_BODY_PAIR_3D_H