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use crate::{AppContext, Layer};
pub struct PerfMetricsLayer {
name: String,
fixed_delta_time: std::time::Duration,
last_fixed_update: std::time::Instant,
fps_timings_max_capacity: usize,
fps_timings: Vec<f32>,
frames_to_skip: u32,
skipped_frames: u32,
max_frame_rate: f32,
}
impl PerfMetricsLayer {
pub fn new() -> Self {
let fps_timings_max_capacity = 300;
PerfMetricsLayer {
name: "PerfMetricsLayer".to_string(),
fixed_delta_time: std::time::Duration::from_secs(0),
last_fixed_update: std::time::Instant::now(),
fps_timings_max_capacity,
fps_timings: Vec::<f32>::with_capacity(fps_timings_max_capacity),
frames_to_skip: 20,
skipped_frames: 0,
max_frame_rate: 60.0,
}
}
}
impl Layer for PerfMetricsLayer {
fn name(&self) -> &String {
return &self.name;
}
fn init(&mut self, app_context: &mut AppContext) {
self.max_frame_rate = app_context.max_frame_rate();
}
fn on_fixed_update(&mut self, _: &mut AppContext) {
let now = std::time::Instant::now();
self.fixed_delta_time = now - self.last_fixed_update;
self.last_fixed_update = now;
}
fn on_frame_update(&mut self, app_context: &mut AppContext) {
if self.skipped_frames < self.frames_to_skip {
self.skipped_frames += 1;
return;
}
self.fps_timings
.insert(0, 1.0 / app_context.delta_time().as_secs_f32());
self.fps_timings.truncate(self.fps_timings_max_capacity);
}
fn on_imgui_update(&mut self, ui: &imgui::Ui, app_context: &mut AppContext) {
imgui::Window::new(imgui::im_str!("Performance Metrics"))
.size([340.0, 250.0], imgui::Condition::FirstUseEver)
.always_auto_resize(true)
.position_pivot([1.0, 0.0])
.position(
[
app_context.windowed_context().window().inner_size().width as f32
/ app_context.imgui_platform().hidpi_factor() as f32,
0.0,
],
imgui::Condition::FirstUseEver,
)
.save_settings(false)
.collapsed(true, imgui::Condition::FirstUseEver)
.build(&ui, || {
ui.text(format!(
"Event Poll Time: {:06.3} ms",
app_context.event_poll_time().as_secs_f64() * 1_000.0
));
ui.text(format!(
"Fixed Delta Time: {:06.3} ms (Timestep: {:06.3})",
self.fixed_delta_time.as_secs_f64() * 1_000.0,
app_context.fixed_timestep().as_secs_f64() * 1_000.0,
));
ui.text(format!(
"Delta Time: {:06.3} ms (Max Frame Rate: {:03.0} FPS)",
app_context.delta_time().as_secs_f64() * 1_000.0,
app_context.max_frame_rate(),
));
if ui
.drag_float(imgui::im_str!("Max Frame Rate"), &mut self.max_frame_rate)
.min(30.0)
.max(300.0)
.display_format(imgui::im_str!("%g"))
.build()
{
app_context.set_min_frame_timestep(std::time::Duration::from_secs_f32(
1.0 / self.max_frame_rate,
));
};
let min_fps =
self.fps_timings.iter().fold(
std::f32::MAX,
|min, &val| {
if val < min {
val
} else {
min
}
},
);
let max_fps =
self.fps_timings
.iter()
.fold(0.0f32, |max, &val| if val > max { val } else { max });
let ave_fps: f32 =
self.fps_timings.iter().sum::<f32>() / self.fps_timings.len() as f32;
let overlay_text = imgui::im_str!(
"Min: {:06.3} | Max: {:06.3} | Ave: {:06.3}",
min_fps,
max_fps,
ave_fps,
);
ui.plot_lines(imgui::im_str!("FPS"), &self.fps_timings)
.graph_size([300.0, 100.0])
.overlay_text(overlay_text.as_ref())
.build();
});
}
fn on_event(&mut self, event: &glutin::event::Event<()>, _: &mut AppContext) {
use glutin::event::{ElementState, Event, KeyboardInput, VirtualKeyCode, WindowEvent};
match event {
Event::WindowEvent {
event:
WindowEvent::KeyboardInput {
input:
KeyboardInput {
virtual_keycode: Some(VirtualKeyCode::V),
state: ElementState::Pressed,
..
},
..
},
..
} => {
use std::io::prelude::*;
let serialized = serde_json::to_string(&self.fps_timings).unwrap();
let my_json = format!(r#"{{"fps": {}}}"#, serialized);
let mut file = std::fs::File::create("data.json").expect("create failed");
file.write_all(my_json.as_bytes()).expect("write failed");
println!("data written to file");
}
_ => (),
}
}
}