1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
use crate::math::Real;
/// Parameters for a time-step of the physics engine.
#[derive(Copy, Clone)]
#[cfg_attr(feature = "serde-serialize", derive(Serialize, Deserialize))]
pub struct IntegrationParameters {
/// The timestep length (default: `1.0 / 60.0`)
pub dt: Real,
/// Minimum timestep size when using CCD with multiple substeps (default `1.0 / 60.0 / 100.0`)
///
/// When CCD with multiple substeps is enabled, the timestep is subdivided
/// into smaller pieces. This timestep subdivision won't generate timestep
/// lengths smaller than `min_dt`.
///
/// Setting this to a large value will reduce the opportunity to performing
/// CCD substepping, resulting in potentially more time dropped by the
/// motion-clamping mechanism. Setting this to an very small value may lead
/// to numerical instabilities.
pub min_ccd_dt: Real,
// /// If `true` and if rapier is compiled with the `parallel` feature, this will enable rayon-based multithreading (default: `true`).
// ///
// /// This parameter is ignored if rapier is not compiled with is `parallel` feature.
// /// Refer to rayon's documentation regarding how to configure the number of threads with either
// /// `rayon::ThreadPoolBuilder::new().num_threads(4).build_global().unwrap()` or `ThreadPool::install`.
// /// Note that using only one thread with `multithreading_enabled` set to `true` will result on a slower
// /// simulation than setting `multithreading_enabled` to `false`.
// pub multithreading_enabled: bool,
// /// If `true`, the world's `step` method will stop right after resolving exactly one CCD event (default: `false`).
// /// This allows the user to take action during a timestep, in-between two CCD events.
// pub return_after_ccd_substep: bool,
/// The Error Reduction Parameter in `[0, 1]` is the proportion of
/// the positional error to be corrected at each time step (default: `0.2`).
pub erp: Real,
/// The Error Reduction Parameter for joints in `[0, 1]` is the proportion of
/// the positional error to be corrected at each time step (default: `0.2`).
pub joint_erp: Real,
/// Each cached impulse are multiplied by this coefficient in `[0, 1]`
/// when they are re-used to initialize the solver (default `1.0`).
pub warmstart_coeff: Real,
/// Correction factor to avoid large warmstart impulse after a strong impact (default `10.0`).
pub warmstart_correction_slope: Real,
/// 0-1: how much of the velocity to dampen out in the constraint solver?
/// (default `1.0`).
pub velocity_solve_fraction: Real,
/// 0-1: multiplier for how much of the constraint violation (e.g. contact penetration)
/// will be compensated for during the velocity solve.
/// If zero, you need to enable the positional solver.
/// If non-zero, you do not need the positional solver.
/// A good non-zero value is around `0.2`.
/// (default `0.0`).
pub velocity_based_erp: Real,
/// Amount of penetration the engine wont attempt to correct (default: `0.005m`).
pub allowed_linear_error: Real,
/// The maximal distance separating two objects that will generate predictive contacts (default: `0.002`).
pub prediction_distance: Real,
/// Amount of angular drift of joint limits the engine wont
/// attempt to correct (default: `0.001rad`).
pub allowed_angular_error: Real,
/// Maximum linear correction during one step of the non-linear position solver (default: `0.2`).
pub max_linear_correction: Real,
/// Maximum angular correction during one step of the non-linear position solver (default: `0.2`).
pub max_angular_correction: Real,
/// Maximum number of iterations performed by the velocity constraints solver (default: `4`).
pub max_velocity_iterations: usize,
/// Maximum number of iterations performed by the position-based constraints solver (default: `1`).
pub max_position_iterations: usize,
/// Minimum number of dynamic bodies in each active island (default: `128`).
pub min_island_size: usize,
/// Maximum number of substeps performed by the solver (default: `1`).
pub max_ccd_substeps: usize,
}
impl IntegrationParameters {
/// Creates a set of integration parameters with the given values.
#[deprecated = "Use `IntegrationParameters { dt: 60.0, ..Default::default() }` instead"]
pub fn new(
dt: Real,
erp: Real,
joint_erp: Real,
warmstart_coeff: Real,
allowed_linear_error: Real,
allowed_angular_error: Real,
max_linear_correction: Real,
max_angular_correction: Real,
prediction_distance: Real,
max_velocity_iterations: usize,
max_position_iterations: usize,
max_ccd_substeps: usize,
) -> Self {
IntegrationParameters {
dt,
erp,
joint_erp,
warmstart_coeff,
allowed_linear_error,
allowed_angular_error,
max_linear_correction,
max_angular_correction,
prediction_distance,
max_velocity_iterations,
max_position_iterations,
max_ccd_substeps,
..Default::default()
}
}
/// The current time-stepping length.
#[inline(always)]
#[deprecated = "You can just read the `IntegrationParams::dt` value directly"]
pub fn dt(&self) -> Real {
self.dt
}
/// The inverse of the time-stepping length, i.e. the steps per seconds (Hz).
///
/// This is zero if `self.dt` is zero.
#[inline(always)]
pub fn inv_dt(&self) -> Real {
if self.dt == 0.0 {
0.0
} else {
1.0 / self.dt
}
}
/// Sets the time-stepping length.
#[inline]
#[deprecated = "You can just set the `IntegrationParams::dt` value directly"]
pub fn set_dt(&mut self, dt: Real) {
assert!(dt >= 0.0, "The time-stepping length cannot be negative.");
self.dt = dt;
}
/// Sets the inverse time-stepping length (i.e. the frequency).
///
/// This automatically recompute `self.dt`.
#[inline]
pub fn set_inv_dt(&mut self, inv_dt: Real) {
if inv_dt == 0.0 {
self.dt = 0.0
} else {
self.dt = 1.0 / inv_dt
}
}
/// Convenience: `velocity_based_erp / dt`
#[inline]
pub(crate) fn velocity_based_erp_inv_dt(&self) -> Real {
self.velocity_based_erp * self.inv_dt()
}
}
impl Default for IntegrationParameters {
fn default() -> Self {
Self {
dt: 1.0 / 60.0,
min_ccd_dt: 1.0 / 60.0 / 100.0,
// multithreading_enabled: true,
erp: 0.2,
joint_erp: 0.2,
velocity_solve_fraction: 1.0,
velocity_based_erp: 0.0,
warmstart_coeff: 1.0,
warmstart_correction_slope: 10.0,
allowed_linear_error: 0.005,
prediction_distance: 0.002,
allowed_angular_error: 0.001,
max_linear_correction: 0.2,
max_angular_correction: 0.2,
max_velocity_iterations: 4,
max_position_iterations: 1,
// FIXME: what is the optimal value for min_island_size?
// It should not be too big so that we don't end up with
// huge islands that don't fit in cache.
// However we don't want it to be too small and end up with
// tons of islands, reducing SIMD parallelism opportunities.
min_island_size: 128,
max_ccd_substeps: 1,
}
}
}