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Avoid bias overrotation in contact resolution

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This commit is contained in:
m4nu3lf 2017-09-18 00:01:19 +01:00
parent bc005a57d3
commit 650d5630af
3 changed files with 37 additions and 12 deletions
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38
servers/physics/body_pair_sw.cpp
View file

@ -46,6 +46,7 @@
//#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) {
@ -71,6 +72,7 @@ void BodyPairSW::contact_added_callback(const Vector3 &p_point_A, const Vector3
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;
@ -82,12 +84,12 @@ void BodyPairSW::contact_added_callback(const Vector3 &p_point_A, const Vector3
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) &&
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;
@ -325,9 +327,7 @@ bool BodyPairSW::setup(real_t p_step) {
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;
Vector3 jb_vec = c.normal * c.acc_bias_impulse;
A->apply_bias_impulse(c.rA + A->get_center_of_mass(), -jb_vec);
B->apply_bias_impulse(c.rB + B->get_center_of_mass(), jb_vec);
c.acc_bias_impulse_center_of_mass = 0;
c.bounce = MAX(A->get_bounce(), B->get_bounce());
if (c.bounce) {
@ -356,7 +356,7 @@ void BodyPairSW::solve(real_t p_step) {
c.active = false; //try to deactivate, will activate itself if still needed
//bias impule
//bias impulse
Vector3 crbA = A->get_biased_angular_velocity().cross(c.rA);
Vector3 crbB = B->get_biased_angular_velocity().cross(c.rB);
@ -372,8 +372,26 @@ void BodyPairSW::solve(real_t p_step) {
Vector3 jb = c.normal * (c.acc_bias_impulse - jbnOld);
A->apply_bias_impulse(c.rA + A->get_center_of_mass(), -jb);
B->apply_bias_impulse(c.rB + B->get_center_of_mass(), jb);
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;
}
@ -382,7 +400,7 @@ void BodyPairSW::solve(real_t p_step) {
Vector3 crB = B->get_angular_velocity().cross(c.rB);
Vector3 dv = B->get_linear_velocity() + crB - A->get_linear_velocity() - crA;
//normal impule
//normal impulse
real_t vn = dv.dot(c.normal);
if (Math::abs(vn) > MIN_VELOCITY) {
@ -399,7 +417,7 @@ void BodyPairSW::solve(real_t p_step) {
c.active = true;
}
//friction impule
//friction impulse
real_t friction = A->get_friction() * B->get_friction();

1
servers/physics/body_pair_sw.h
View file

@ -59,6 +59,7 @@ class BodyPairSW : public ConstraintSW {
real_t acc_normal_impulse; // accumulated normal impulse (Pn)
Vector3 acc_tangent_impulse; // accumulated tangent impulse (Pt)
real_t acc_bias_impulse; // accumulated normal impulse for position bias (Pnb)
real_t acc_bias_impulse_center_of_mass; // accumulated normal impulse for position bias applied to com
real_t mass_normal;
real_t bias;
real_t bounce;

10
servers/physics/body_sw.h
View file

@ -223,10 +223,16 @@ public:
angular_velocity += _inv_inertia_tensor.xform(p_j);
}
_FORCE_INLINE_ void apply_bias_impulse(const Vector3 &p_pos, const Vector3 &p_j) {
_FORCE_INLINE_ void apply_bias_impulse(const Vector3 &p_pos, const Vector3 &p_j, real_t p_max_delta_av = -1.0) {
biased_linear_velocity += p_j * _inv_mass;
biased_angular_velocity += _inv_inertia_tensor.xform((p_pos - center_of_mass).cross(p_j));
if (p_max_delta_av != 0.0) {
Vector3 delta_av = _inv_inertia_tensor.xform((p_pos - center_of_mass).cross(p_j));
if (p_max_delta_av > 0 && delta_av.length() > p_max_delta_av) {
delta_av = delta_av.normalized() * p_max_delta_av;
}
biased_angular_velocity += delta_av;
}
}
_FORCE_INLINE_ void apply_bias_torque_impulse(const Vector3 &p_j) {