1#import bevy_ui::ui_vertex_output::UiVertexOutput
2
3@group(1) @binding(0) var<storage> values: array<f32>;
4struct Config {
5    dt_min: f32,
6    dt_max: f32,
7    dt_min_log2: f32,
8    dt_max_log2: f32,
9    proportional_width: u32,
10}
11@group(1) @binding(1) var<uniform> config: Config;
12
13const RED: vec4<f32> = vec4(1.0, 0.0, 0.0, 1.0);
14const GREEN: vec4<f32> = vec4(0.0, 1.0, 0.0, 1.0);
15
16// Gets a color based on the delta time
17// TODO use customizable gradient
18fn color_from_dt(dt: f32) -> vec4<f32> {
19    return mix(GREEN, RED, dt / config.dt_max);
20}
21
22// Draw an SDF square
23fn sdf_square(pos: vec2<f32>, half_size: vec2<f32>, offset: vec2<f32>) -> f32 {
24    let p = pos - offset;
25    let dist = abs(p) - half_size;
26    let outside_dist = length(max(dist, vec2<f32>(0.0, 0.0)));
27    let inside_dist = min(max(dist.x, dist.y), 0.0);
28    return outside_dist + inside_dist;
29}
30
31@fragment
32fn fragment(in: UiVertexOutput) -> @location(0) vec4<f32> {
33    let dt_min = config.dt_min;
34    let dt_max = config.dt_max;
35    let dt_min_log2 = config.dt_min_log2;
36    let dt_max_log2 = config.dt_max_log2;
37
38    // The general algorithm is highly inspired by
39    // <https://asawicki.info/news_1758_an_idea_for_visualization_of_frame_times>
40
41    let len = arrayLength(&values);
42    var graph_width = 0.0;
43    for (var i = 1u; i <= len; i += 1u) {
44        let dt = values[len - i];
45
46        var frame_width: f32;
47        if config.proportional_width == 1u {
48            frame_width = (dt / dt_min) / f32(len);
49        } else {
50            frame_width = 0.015;
51        }
52
53        let frame_height_factor = (log2(dt) - dt_min_log2) / (dt_max_log2 - dt_min_log2);
54        let frame_height_factor_norm = min(max(0.0, frame_height_factor), 1.0);
55        let frame_height = mix(0.0, 1.0, frame_height_factor_norm);
56
57        let size = vec2(frame_width, frame_height) / 2.0;
58        let offset = vec2(1.0 - graph_width - size.x, 1. - size.y);
59        if (sdf_square(in.uv, size, offset) < 0.0) {
60            return color_from_dt(dt);
61        }
62
63        graph_width += frame_width;
64    }
65
66    return vec4(0.0, 0.0, 0.0, 0.5);
67}
68