How do I start rendering text?

[Dakota-LM]

To start, I'm very new to both Rust and the agb crate. I've built the "pong" game to the point that both paddles move (one with "ai") and when the ball hits either the left or right side, past the corresponding paddle, it panics because I placed a todo! macro.

Next up I want to add a scoreboard with generic text, and I'm not sure how the whole font/textwriter/textrenderer thing works. This would also be very helpful for basic debugging. Everything is run through mgba-qt, so I don't really get great debugging info in the console. I could be going about that all wrong, though.

[chinatsu]

I'm sure you've probably found this example already. If you haven't:

I recommend having a look at this provided example: https://github.com/agbrs/agb/blob/master/agb/examples/text_render.rs

The set_background_palette_raw-call sets the desired palette. calls such as vram.new_dynamic_tile().fill_with(0) uses the integer as an index to the palette, as does let mut writer = renderer.writer(1, 2, &mut bg, &mut vram) with the two first arguments (fg and bg respectively). If I understand this correctly, the 2d-loop that calls bg.set_tile renders the background_tiles onto bg (basically flush the whole screen w/ the desired color), and the writer is configured to write onto the bg as well, so the result of text+background color is on the same P0-"layer". Then, bg.commit(&mut vram) actually sends the content onto the screen.

The example doesn't clear the bg in the loop, so some artifacts might stick from the previous rendered frame. In my own experiments, I do something more like this:

#[agb::entry]
fn main(mut gba: agb::Gba) -> ! {
    let (gfx, mut vram) = gba.display.video.tiled0();
    let vblank = agb::interrupt::VBlank::get();

    vram.set_background_palette_raw(&[
        0x0000, 0x0ff0, 0x00ff, 0xf00f, 0xf0f0, 0x0f0f, 0xffff, 0x5555, 0x0000, 0x0000, 0x0000,
        0x0000, 0x0000, 0x0000, 0x0000, 0x0000,
    ]);

    let mut bg = gfx.background(
        Priority::P0,
        RegularBackgroundSize::Background32x32,
        TileFormat::FourBpp,
    );
    bg.set_visible(true);


    loop {
        let background_tile = vram.new_dynamic_tile().fill_with(6);

        // fill the screen with our tile
        for y in 0..20u16 {
            for x in 0..30u16 {
                bg.set_tile(
                    &mut vram,
                    (x, y),
                    &background_tile.tile_set(),
                    background_tile.tile_setting(),
                );
            }
        }

        let mut renderer = FONT.render_text((1u16, 3u16));
        let writer = renderer.writer(1, 6, &mut bg, &mut vram);
        writeln!(&mut writer, "Hello!!!").unwrap(); // in reality, I change the text every now and then

        vblank.wait_for_vblank();
        // commit the bg and text onto the vram
        bg.commit(&mut vram);

        // clear the renderer and the bg
        renderer.clear(&mut vram);
        bg.clear(&mut vram);

        
        vram.remove_dynamic_tile(background_tile);
    }
}

[corwinkuiper]

For debugging, use agb::println. This will output in the mgba console. You do need to set up mgba to actually output this, you can do this through the UI or on the CLI. For the CLI see how the template does it, https://github.com/agbrs/agb/blob/master/template/.cargo/config.toml. For the UI, Tools > Settings > Logging and enable all of GBA Debug and log to console. . Then if you run mgba through the terminal you'll see printlns get printed.

For in game text, right now all our APIs are not very good. As you're using the managed sprites stuff (which will probably be removed soon), you'll want to use backgrounds to render text. The example for which is https://github.com/agbrs/agb/blob/master/agb/examples/text_render.rs. If you have any specific problems therein let us know.

Aplologies for the late reply, we were working heavily on our jam game, https://setsquare.itch.io/dungeon-tactics-advance, and did not have time to keep on top of the rest of agb.