forked from bevyengine/bevy
-
Notifications
You must be signed in to change notification settings - Fork 0
/
virtual_time.rs
218 lines (196 loc) · 6.98 KB
/
virtual_time.rs
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
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
//! Shows how `Time<Virtual>` can be used to pause, resume, slow down
//! and speed up a game.
use std::time::Duration;
use bevy::{
input::common_conditions::input_just_pressed, prelude::*,
time::common_conditions::on_real_timer,
};
fn main() {
App::new()
.add_plugins(DefaultPlugins)
.add_systems(Startup, setup)
.add_systems(
Update,
(
move_virtual_time_sprites,
move_real_time_sprites,
toggle_pause.run_if(input_just_pressed(KeyCode::Space)),
change_time_speed::<1>.run_if(input_just_pressed(KeyCode::ArrowUp)),
change_time_speed::<-1>.run_if(input_just_pressed(KeyCode::ArrowDown)),
(update_virtual_time_info_text, update_real_time_info_text)
// update the texts on a timer to make them more readable
// `on_timer` run condition uses `Virtual` time meaning it's scaled
// and would result in the UI updating at different intervals based
// on `Time<Virtual>::relative_speed` and `Time<Virtual>::is_paused()`
.run_if(on_real_timer(Duration::from_millis(250))),
),
)
.run();
}
/// `Real` time related marker
#[derive(Component)]
struct RealTime;
/// `Virtual` time related marker
#[derive(Component)]
struct VirtualTime;
/// Setup the example
fn setup(mut commands: Commands, asset_server: Res<AssetServer>, mut time: ResMut<Time<Virtual>>) {
// start with double `Virtual` time resulting in one of the sprites moving at twice the speed
// of the other sprite which moves based on `Real` (unscaled) time
time.set_relative_speed(2.);
commands.spawn(Camera2dBundle::default());
let virtual_color = LegacyColor::GOLD;
let sprite_scale = Vec2::splat(0.5).extend(1.);
let texture_handle = asset_server.load("branding/icon.png");
// the sprite moving based on real time
commands.spawn((
SpriteBundle {
texture: texture_handle.clone(),
transform: Transform::from_scale(sprite_scale),
..default()
},
RealTime,
));
// the sprite moving based on virtual time
commands.spawn((
SpriteBundle {
texture: texture_handle,
sprite: Sprite {
color: virtual_color,
..default()
},
transform: Transform {
scale: sprite_scale,
translation: Vec3::new(0., -160., 0.),
..default()
},
..default()
},
VirtualTime,
));
// info UI
let font_size = 40.;
commands
.spawn(NodeBundle {
style: Style {
display: Display::Flex,
justify_content: JustifyContent::SpaceBetween,
width: Val::Percent(100.),
position_type: PositionType::Absolute,
top: Val::Px(0.),
padding: UiRect::all(Val::Px(20.0)),
..default()
},
..default()
})
.with_children(|builder| {
// real time info
builder.spawn((
TextBundle::from_section(
"",
TextStyle {
font_size,
..default()
},
),
RealTime,
));
// keybindings
builder.spawn(
TextBundle::from_section(
"CONTROLS\nUn/Pause: Space\nSpeed+: Up\nSpeed-: Down",
TextStyle {
font_size,
color: LegacyColor::rgb(0.85, 0.85, 0.85),
..default()
},
)
.with_text_justify(JustifyText::Center),
);
// virtual time info
builder.spawn((
TextBundle::from_section(
"",
TextStyle {
font_size,
color: virtual_color,
..default()
},
)
.with_text_justify(JustifyText::Right),
VirtualTime,
));
});
}
/// Move sprites using `Real` (unscaled) time
fn move_real_time_sprites(
mut sprite_query: Query<&mut Transform, (With<Sprite>, With<RealTime>)>,
// `Real` time which is not scaled or paused
time: Res<Time<Real>>,
) {
for mut transform in sprite_query.iter_mut() {
// move roughly half the screen in a `Real` second
// when the time is scaled the speed is going to change
// and the sprite will stay still the the time is paused
transform.translation.x = get_sprite_translation_x(time.elapsed_seconds());
}
}
/// Move sprites using `Virtual` (scaled) time
fn move_virtual_time_sprites(
mut sprite_query: Query<&mut Transform, (With<Sprite>, With<VirtualTime>)>,
// the default `Time` is either `Time<Virtual>` in regular systems
// or `Time<Fixed>` in fixed timestep systems so `Time::delta()`,
// `Time::elapsed()` will return the appropriate values either way
time: Res<Time>,
) {
for mut transform in sprite_query.iter_mut() {
// move roughly half the screen in a `Virtual` second
// when time is scaled using `Time<Virtual>::set_relative_speed` it's going
// to move at a different pace and the sprite will stay still when time is
// `Time<Virtual>::is_paused()`
transform.translation.x = get_sprite_translation_x(time.elapsed_seconds());
}
}
fn get_sprite_translation_x(elapsed: f32) -> f32 {
elapsed.sin() * 500.
}
/// Update the speed of `Time<Virtual>.` by `DELTA`
fn change_time_speed<const DELTA: i8>(mut time: ResMut<Time<Virtual>>) {
let time_speed = (time.relative_speed() + DELTA as f32)
.round()
.clamp(0.25, 5.);
// set the speed of the virtual time to speed it up or slow it down
time.set_relative_speed(time_speed);
}
/// pause or resume `Relative` time
fn toggle_pause(mut time: ResMut<Time<Virtual>>) {
if time.is_paused() {
time.unpause();
} else {
time.pause();
}
}
/// Update the `Real` time info text
fn update_real_time_info_text(time: Res<Time<Real>>, mut query: Query<&mut Text, With<RealTime>>) {
for mut text in &mut query {
text.sections[0].value = format!(
"REAL TIME\nElapsed: {:.1}\nDelta: {:.5}\n",
time.elapsed_seconds(),
time.delta_seconds(),
);
}
}
/// Update the `Virtual` time info text
fn update_virtual_time_info_text(
time: Res<Time<Virtual>>,
mut query: Query<&mut Text, With<VirtualTime>>,
) {
for mut text in &mut query {
text.sections[0].value = format!(
"VIRTUAL TIME\nElapsed: {:.1}\nDelta: {:.5}\nSpeed: {:.2}",
time.elapsed_seconds(),
time.delta_seconds(),
time.relative_speed()
);
}
}