draw_state.rs

extern crate piston_window;
extern crate find_folder;

use piston_window::draw_state::Blend;
use piston_window::*;

fn main() {
    println!("Press A to change blending");
    println!("Press S to change clip inside/out");

    let mut window: PistonWindow = WindowSettings::new(
            "piston: draw_state",
            [600, 600]
        )
        .exit_on_esc(true)
        .samples(4)
        .build()
        .unwrap();

    let assets = find_folder::Search::ParentsThenKids(3, 3)
        .for_folder("assets").unwrap();
    let blends = [Blend::Alpha, Blend::Add, Blend::Invert, Blend::Multiply];
    let mut blend = 0;
    let mut clip_inside = true;
    let rust_logo = Texture::from_path(&mut window.create_texture_context(),
                                       assets.join("rust.png"),
                                       Flip::None,
                                       &TextureSettings::new()).unwrap();
    window.set_lazy(true);
    while let Some(e) = window.next() {
        window.draw_2d(&e, |c, g, _| {
            clear([0.8, 0.8, 0.8, 1.0], g);
            g.clear_stencil(0);
            Rectangle::new([1.0, 0.0, 0.0, 1.0])
                .draw([0.0, 0.0, 100.0, 100.0], &c.draw_state, c.transform, g);

            let draw_state = c.draw_state.blend(blends[blend]);
            Rectangle::new([0.5, 1.0, 0.0, 0.3])
                .draw([50.0, 50.0, 100.0, 100.0], &draw_state, c.transform, g);

            let transform = c.transform.trans(100.0, 100.0);
            // Clip rectangle from upper left corner.
            let clipped = c.draw_state.scissor([100, 100, 100, 100]);
            Image::new().draw(&rust_logo, &clipped, transform, g);

            let transform = c.transform.trans(200.0, 200.0);
            Ellipse::new([1.0, 0.0, 0.0, 1.0])
                .draw([0.0, 0.0, 50.0, 50.0], &DrawState::new_clip(), transform, g);
            Image::new().draw(&rust_logo,
                &if clip_inside { DrawState::new_inside() }
                else { DrawState::new_outside() },
                transform, g);
        });

        if let Some(Button::Keyboard(Key::A)) = e.press_args() {
            blend = (blend + 1) % blends.len();
            println!("Changed blending to {:?}", blend);
        }

        if let Some(Button::Keyboard(Key::S)) = e.press_args() {
            clip_inside = !clip_inside;
            if clip_inside {
                println!("Changed to clip inside");
            } else {
                println!("Changed to clip outside");
            }
        }
    }
}