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use crate::{
Id, IdMap, InputState,
emath::{NumExt as _, remap_clamp},
};
#[derive(Clone, Default)]
pub(crate) struct AnimationManager {
bools: IdMap<BoolAnim>,
values: IdMap<ValueAnim>,
}
#[derive(Clone, Debug)]
struct BoolAnim {
last_value: f32,
last_tick: f64,
}
#[derive(Clone, Debug)]
struct ValueAnim {
from_value: f32,
to_value: f32,
/// when did `value` last toggle?
toggle_time: f64,
}
impl AnimationManager {
/// See [`crate::Context::animate_bool`] for documentation
pub fn animate_bool(
&mut self,
input: &InputState,
animation_time: f32,
id: Id,
value: bool,
) -> f32 {
let (start, end) = if value { (0.0, 1.0) } else { (1.0, 0.0) };
match self.bools.get_mut(&id) {
None => {
self.bools.insert(
id,
BoolAnim {
last_value: end,
last_tick: input.time - input.stable_dt as f64,
},
);
end
}
Some(anim) => {
let BoolAnim {
last_value,
last_tick,
} = anim;
let current_time = input.time;
let elapsed = ((current_time - *last_tick) as f32).at_most(input.stable_dt);
let new_value = *last_value + (end - start) * elapsed / animation_time;
*last_value = if new_value.is_finite() {
new_value.clamp(0.0, 1.0)
} else {
end
};
*last_tick = current_time;
*last_value
}
}
}
pub fn animate_value(
&mut self,
input: &InputState,
animation_time: f32,
id: Id,
value: f32,
) -> f32 {
match self.values.get_mut(&id) {
None => {
self.values.insert(
id,
ValueAnim {
from_value: value,
to_value: value,
toggle_time: -f64::INFINITY, // long time ago
},
);
value
}
Some(anim) => {
let time_since_toggle = (input.time - anim.toggle_time) as f32;
// On the frame we toggle we don't want to return the old value,
// so we extrapolate forwards by half a frame:
let time_since_toggle = time_since_toggle + input.predicted_dt / 2.0;
let current_value = remap_clamp(
time_since_toggle,
0.0..=animation_time,
anim.from_value..=anim.to_value,
);
if anim.to_value != value {
anim.from_value = current_value; //start new animation from current position of playing animation
anim.to_value = value;
anim.toggle_time = input.time;
}
if animation_time == 0.0 {
anim.from_value = value;
anim.to_value = value;
}
current_value
}
}
}
}