game_loop/
base.rs

1use crate::*;
2
3pub struct GameLoop<G, T: TimeTrait, W> {
4    pub game: G,
5    pub updates_per_second: u32,
6    pub max_frame_time: f64,
7    pub exit_next_iteration: bool,
8    pub window: W,
9    pub window_occluded: bool,
10
11    fixed_time_step: f64,
12    number_of_updates: u64,
13    number_of_renders: u64,
14    last_frame_time: f64,
15    running_time: f64,
16    accumulated_time: f64,
17    blending_factor: f64,
18    previous_instant: T,
19    current_instant: T,
20}
21
22impl<G, T: TimeTrait, W> GameLoop<G, T, W> {
23    pub fn new(game: G, updates_per_second: u32, max_frame_time: f64, window: W) -> Self {
24        Self {
25            game,
26            updates_per_second,
27            max_frame_time,
28            window,
29            window_occluded: false,
30            exit_next_iteration: false,
31
32            fixed_time_step: 1.0 / updates_per_second as f64,
33            number_of_updates: 0,
34            number_of_renders: 0,
35            running_time: 0.0,
36            accumulated_time: 0.0,
37            blending_factor: 0.0,
38            previous_instant: T::now(),
39            current_instant: T::now(),
40            last_frame_time: 0.0,
41        }
42    }
43
44    pub fn next_frame<U, R>(&mut self, mut update: U, mut render: R) -> bool
45        where U: FnMut(&mut GameLoop<G, T, W>),
46              R: FnMut(&mut GameLoop<G, T, W>),
47    {
48        let g = self;
49
50        if g.exit_next_iteration { return false; }
51
52        g.current_instant = T::now();
53
54        let mut elapsed = g.current_instant.sub(&g.previous_instant);
55        if elapsed > g.max_frame_time { elapsed = g.max_frame_time; }
56
57        g.last_frame_time = elapsed;
58        g.running_time += elapsed;
59        g.accumulated_time += elapsed;
60
61        while g.accumulated_time >= g.fixed_time_step {
62            update(g);
63
64            g.accumulated_time -= g.fixed_time_step;
65            g.number_of_updates += 1;
66        }
67
68        g.blending_factor = g.accumulated_time / g.fixed_time_step;
69
70        if g.window_occluded && T::supports_sleep() {
71            T::sleep(g.fixed_time_step);
72        } else {
73            render(g);
74            g.number_of_renders += 1;
75        }
76
77        g.previous_instant = g.current_instant;
78
79        true
80    }
81
82    pub fn re_accumulate(&mut self) {
83        let g = self;
84
85        g.current_instant = T::now();
86
87        let prev_elapsed = g.last_frame_time;
88        let new_elapsed = g.current_instant.sub(&g.previous_instant);
89
90        let delta = new_elapsed - prev_elapsed;
91
92        // We don't update g.last_frame_time since this additional time in the
93        // render function is considered part of the current frame.
94
95        g.running_time += delta;
96        g.accumulated_time += delta;
97
98        g.blending_factor = g.accumulated_time / g.fixed_time_step;
99    }
100
101    pub fn exit(&mut self) {
102        self.exit_next_iteration = true;
103    }
104
105    pub fn set_updates_per_second(&mut self, new_updates_per_second: u32) {
106        self.updates_per_second = new_updates_per_second;
107        self.fixed_time_step = 1.0 / new_updates_per_second as f64;
108    }
109
110    pub fn fixed_time_step(&self) -> f64 {
111        self.fixed_time_step
112    }
113
114    pub fn number_of_updates(&self) -> u64 {
115        self.number_of_updates
116    }
117
118    pub fn number_of_renders(&self) -> u64 {
119        self.number_of_renders
120    }
121
122    pub fn last_frame_time(&self) -> f64 {
123        self.last_frame_time
124    }
125
126    pub fn running_time(&self) -> f64 {
127        self.running_time
128    }
129
130    pub fn accumulated_time(&self) -> f64 {
131        self.accumulated_time
132    }
133
134    pub fn blending_factor(&self) -> f64 {
135        self.blending_factor
136    }
137
138    pub fn previous_instant(&self) -> T {
139        self.previous_instant
140    }
141
142    pub fn current_instant(&self) -> T {
143        self.current_instant
144    }
145}
game_loop/base.rs

game_loop/
base.rs
