egui/
animation_manager.rs

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1use crate::{
2    emath::{remap_clamp, NumExt as _},
3    Id, IdMap, InputState,
4};
5
6#[derive(Clone, Default)]
7pub(crate) struct AnimationManager {
8    bools: IdMap<BoolAnim>,
9    values: IdMap<ValueAnim>,
10}
11
12#[derive(Clone, Debug)]
13struct BoolAnim {
14    last_value: f32,
15    last_tick: f64,
16}
17
18#[derive(Clone, Debug)]
19struct ValueAnim {
20    from_value: f32,
21
22    to_value: f32,
23
24    /// when did `value` last toggle?
25    toggle_time: f64,
26}
27
28impl AnimationManager {
29    /// See [`crate::Context::animate_bool`] for documentation
30    pub fn animate_bool(
31        &mut self,
32        input: &InputState,
33        animation_time: f32,
34        id: Id,
35        value: bool,
36    ) -> f32 {
37        let (start, end) = if value { (0.0, 1.0) } else { (1.0, 0.0) };
38        match self.bools.get_mut(&id) {
39            None => {
40                self.bools.insert(
41                    id,
42                    BoolAnim {
43                        last_value: end,
44                        last_tick: input.time - input.stable_dt as f64,
45                    },
46                );
47                end
48            }
49            Some(anim) => {
50                let BoolAnim {
51                    last_value,
52                    last_tick,
53                } = anim;
54                let current_time = input.time;
55                let elapsed = ((current_time - *last_tick) as f32).at_most(input.stable_dt);
56                let new_value = *last_value + (end - start) * elapsed / animation_time;
57                *last_value = if new_value.is_finite() {
58                    new_value.clamp(0.0, 1.0)
59                } else {
60                    end
61                };
62                *last_tick = current_time;
63                *last_value
64            }
65        }
66    }
67
68    pub fn animate_value(
69        &mut self,
70        input: &InputState,
71        animation_time: f32,
72        id: Id,
73        value: f32,
74    ) -> f32 {
75        match self.values.get_mut(&id) {
76            None => {
77                self.values.insert(
78                    id,
79                    ValueAnim {
80                        from_value: value,
81                        to_value: value,
82                        toggle_time: -f64::INFINITY, // long time ago
83                    },
84                );
85                value
86            }
87            Some(anim) => {
88                let time_since_toggle = (input.time - anim.toggle_time) as f32;
89                // On the frame we toggle we don't want to return the old value,
90                // so we extrapolate forwards by half a frame:
91                let time_since_toggle = time_since_toggle + input.predicted_dt / 2.0;
92                let current_value = remap_clamp(
93                    time_since_toggle,
94                    0.0..=animation_time,
95                    anim.from_value..=anim.to_value,
96                );
97                if anim.to_value != value {
98                    anim.from_value = current_value; //start new animation from current position of playing animation
99                    anim.to_value = value;
100                    anim.toggle_time = input.time;
101                }
102                if animation_time == 0.0 {
103                    anim.from_value = value;
104                    anim.to_value = value;
105                }
106                current_value
107            }
108        }
109    }
110}
egui/animation_manager.rs

egui/
animation_manager.rs
