fxparty.rs

//! See https://github.com/ocornut/imgui/issues/3606
use imgui::*;

mod support;

fn main() {
    let system = support::init(file!());
    system.main_loop(move |_, ui| {
        fx_window(ui, 0, |d, a, _b, sz, _mouse, t| {
            for n in 0..(((1.0 + (t * 5.7).sin()) * 40.0) as isize).max(0) {
                d.add_circle(
                    [a[0] + sz[0] * 0.5, a[1] + sz[1] * 0.5],
                    sz[1] * (0.01 + (n as f32) * 0.03),
                    col32(255, (140 - n * 4) as u8, (n * 3) as u8, 255),
                ).build();
            }
        });
        fx_window(ui, 1, |d, a, b, sz, _m, t0| {
            for t in (0..100).map(|t| (t as f32 + t0) / 100.0) {
                let mut cp0 = [a[0], b[1]];
                let mut cp1 = b;
                let ts = t - t0;
                cp0[0] += (0.4 + t.sin() * 0.3) * sz[0];
                cp1[0] -= (0.4 + t.cos() * 0.4) * sz[0];
                cp0[1] -= (0.5 + (ts * ts).cos() * 0.4) * sz[1];
                cp1[1] -= (0.5 + (ts * t).sin() * 0.3) * sz[1];
                d.add_bezier_curve([a[0], b[1]], cp0, cp1, b, col32((100f32 + (ts*150f32)) as u8, (255f32 - ts*150f32) as u8, 60, (ts * 200f32) as u8))
                    .thickness(5.0)
                    .build();
            }
        });
    });
}
fn col32(r: u8, g: u8, b: u8, a: u8) -> ImColor32 {
    ImColor32::from_rgba(r, g, b, a)
}
type V2 = [f32; 2];
fn fx_window(ui: &Ui<'_>, n: usize, fx: impl FnOnce(&DrawListMut<'_>, V2, V2, V2, V2, f32)) {
    let pos = [10.0 + (n / 3) as f32 * 350.0, 10.0 + (n % 3) as f32 * 250.0];
    Window::new(&im_str!("FX {}", n))
        .position(pos, Condition::FirstUseEver)
        // .size([320.0, 180.0], Condition::FirstUseEver)
        .always_auto_resize(true)
        .build(ui, || {
            let size = [320.0, 180.0];
            ui.invisible_button(im_str!("canvas"), size);
            let p0 = ui.item_rect_min();
            let p1 = ui.item_rect_max();
            let mouse_data = {
                let io = ui.io();
                [
                    (io.mouse_pos[0] - p0[0]) / size[0],
                    (io.mouse_pos[1] - p0[1]) / size[1],
                    // FIXME: why isn't `mouse_down_duration` pub...
                    // io.mouse_down_duration[0],
                    // io.mouse_down_duration[1],
                ]
            };
            let draw_list = ui.get_window_draw_list();
            draw_list.with_clip_rect(p0, p1, || {
                fx(&draw_list, p0, p1, size, mouse_data, ui.time() as f32);
            });
        });
}