concinnity-core 0.19.0

Runtime vocabulary for the Concinnity engine: GPU layouts, ECS components, registry, CPU kernels
Documentation 
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

// Regions that record what is inside them and resist nothing.
//
// A sensor rides the same sweep every other body does and leaves it by its own
// door, so this stage is handed the pairs it cares about already filtered and
// already sorted by slot. What is left is to measure each pair exactly
// (`overlap`), remember which pairs were overlapping so a boundary can be told
// from a state (`track`), and turn each boundary into the crossings a caller
// reads.
//
// A boundary test at step boundaries cannot see a body that covered the whole
// region between two of them, so `swept` answers that one off the same sweep
// the continuous-collision stage runs, and both of its crossings are recorded
// on the step it happened.
//
// Every pair is measured every step rather than carried forward from the last
// one. A pair only reaches here with a region on one side, so there are few of
// them however many bodies the world holds, and a carried answer would have to
// be invalidated by every way a body can arrive somewhere -- including the one
// where it is placed inside a region and never moves again.
//
// The queues are reserved once and capped. A caller that stops draining, or a
// world with more regions in it than the reservation covers, is declined and
// counted rather than quietly growing a buffer inside a step.

mod overlap;
pub(super) mod swept;
mod track;

use alloc::vec::Vec;

use crate::memory::Pool;

use crate::physics::SensorCrossing;

use super::body::Body;
use super::broadphase::Pair;
use super::world::{body_at, handle_at};

use track::Overlap;

/// The sensor regions' side of a step: what is inside each of them, and what
/// crossed a boundary to get there.
pub(crate) struct Sensors {
    overlaps: Vec<Overlap>,
    previous: Vec<Overlap>,
    crossings: Vec<SensorCrossing>,
    overflows: u32,
}

impl Sensors {
    pub(crate) fn with_capacity(capacity: usize) -> Self {
        Sensors {
            overlaps: Vec::with_capacity(capacity),
            previous: Vec::with_capacity(capacity),
            crossings: Vec::with_capacity(capacity),
            overflows: 0,
        }
    }

    /// Measure this step's sensor pairs and record every boundary crossed
    /// since the last one.
    ///
    /// `pairs` is the sweep's sensor list: sorted by slot, with a region on at
    /// least one side of every entry.
    pub(crate) fn resolve(&mut self, bodies: &Pool<Body>, pairs: &[Pair]) {
        core::mem::swap(&mut self.overlaps, &mut self.previous);
        self.overlaps.clear();

        let Sensors {
            overlaps,
            previous,
            crossings,
            overflows,
        } = self;

        for &pair in pairs {
            let (Some(a), Some(b)) = (
                bodies.get_at(pair.0 as usize),
                bodies.get_at(pair.1 as usize),
            ) else {
                continue;
            };
            if !overlap::overlapping(a, b) {
                continue;
            }
            let (Some(a), Some(b)) = (handle_at(bodies, pair.0), handle_at(bodies, pair.1)) else {
                continue;
            };
            if overlaps.len() == overlaps.capacity() {
                *overflows = overflows.saturating_add(1);
                continue;
            }
            overlaps.push(Overlap { pair, a, b });
        }

        track::transitions(previous, overlaps, |crossed, entered| {
            // Either side may be a region: two of them overlapping record a
            // crossing each, and a region whose body has gone records none.
            for (sensor, other) in [(crossed.a, crossed.b), (crossed.b, crossed.a)] {
                let Some(tag) = body_at(bodies, sensor).and_then(Body::sensor_tag) else {
                    continue;
                };
                let crossing = SensorCrossing {
                    tag,
                    other: body_at(bodies, other).map(|_| other),
                    entered,
                };
                if crossings.len() == crossings.capacity() {
                    *overflows = overflows.saturating_add(1);
                    continue;
                }
                crossings.push(crossing);
            }
        });
    }

    /// Record a body that crossed clean through a region inside one step:
    /// the entry and the exit both, since neither boundary was ever sampled.
    pub(crate) fn record_pass_through(&mut self, bodies: &Pool<Body>, mover: u32, region: u32) {
        let (Some(tag), Some(other)) = (
            bodies.get_at(region as usize).and_then(Body::sensor_tag),
            handle_at(bodies, mover),
        ) else {
            return;
        };
        for entered in [true, false] {
            if self.crossings.len() == self.crossings.capacity() {
                self.overflows = self.overflows.saturating_add(1);
                continue;
            }
            self.crossings.push(SensorCrossing {
                tag,
                other: Some(other),
                entered,
            });
        }
    }

    /// Move the recorded crossings into `out`, oldest first. Both the queue
    /// and `out` keep their capacity.
    pub(crate) fn drain_into(&mut self, out: &mut Vec<SensorCrossing>) {
        out.clear();
        out.append(&mut self.crossings);
    }

    #[cfg(test)]
    /// Crossings and overlaps the reservation had no room for.
    pub(crate) fn overflows(&self) -> u32 {
        self.overflows
    }

    #[cfg(test)]
    pub(crate) fn clear_overflows(&mut self) {
        self.overflows = 0;
    }

    #[cfg(test)]
    /// Pairs currently overlapping.
    pub(crate) fn overlap_count(&self) -> usize {
        self.overlaps.len()
    }

    pub(crate) fn reserved_bytes(&self) -> u64 {
        ((self.overlaps.capacity() + self.previous.capacity()) * size_of::<Overlap>()
            + self.crossings.capacity() * size_of::<SensorCrossing>()) as u64
    }
}