GBA don't display all tiles that I pass

[rzru]

Hello!

First of all, thank you for your great project! I have a question. It might be stupid but I am only starting to dive into GBA development, so sorry for that!

I have a 224x192 tileset. I load it with include_gfx! macro.

version = "1.0"

[image.roads]
filename = "testik-tileset.png"
tile_size = "8x8"
colours = 256

I try to display tileset on the screen with the following code:

#![no_std]
#![no_main]
#![cfg_attr(test, feature(custom_test_frameworks))]
#![cfg_attr(test, reexport_test_harness_main = "test_main")]
#![cfg_attr(test, test_runner(agb::test_runner::test_runner))]

use agb::{
    display::{
        tiled::{
            AffineBackgroundSize, AffineMap, MapLoan, TileFormat, TileSet, TiledMap, VRamManager,
        },
        Priority,
    },
    include_gfx,
};

include_gfx!("gfx/roads.toml");

fn load_level(bg: &mut MapLoan<AffineMap>, mut vram: &mut VRamManager) {
    let tileset = TileSet::new(roads::roads.tiles, TileFormat::FourBpp);
    let tiles_x = 28;
    let tiles_y = 24;
    for y in 0..20u16 {
        for x in 0..30u16 {
            if x >= tiles_x || y >= tiles_y {
                continue;
            }
            bg.set_tile(&mut vram, (x, y).into(), &tileset, (x + y * tiles_x) as u8);
        }
    }
}

#[agb::entry]
fn main(mut gba: agb::Gba) -> ! {
    // Get the OAM manager
    // let object = gba.display.object.get();
    let (gfx, mut vram) = gba.display.video.tiled2();
    let vblank = agb::interrupt::VBlank::get();

    vram.set_background_palettes(roads::PALETTES);

    let mut bg = gfx.background(Priority::P0, AffineBackgroundSize::Background128x128);
    load_level(&mut bg, &mut vram);

    bg.commit(&mut vram);
    bg.show();

    loop {
        vblank.wait_for_vblank();
    }
}

and I expect it to display the whole tileset without the last couple of rows as they are out of boundaries. however that's what I see:

I wonder if it's something intended and there are restrictions that I need to consider or is this some kind of bug.

Thank you kindly!

[corwinkuiper]

Hey! I've had a look through, and I've found two issues.

1. You're using affine 256 colours, but you've got TileSet::new(roads::roads.tiles, TileFormat::FourBpp);, this is trying to use the tileset as paletted 16. Should instead use TileSet::new(roads::roads.tiles, TileFormat::EightBpp); (@gwilymk maybe this can be automatic).
2. And a bug! Even if you do this it still might not work due to some alignment issues in agb. I've made a PR to fix this (Align tiles to a 2 byte boundary #337). Once it's merged in I'll release 0.12.2, so you can continue!

Thanks for your kind words and good luck with your game!

[rzru]

working as intended now, thanks!

[rzru]

@corwinkuiper or... no. looks like it renders a part of the tileset as intended but then starts over again. I switched from FourBpp to EightBpp

[rzru]

to be precise: it renders 256 tiles and then starts over again.

[corwinkuiper]

The 256 tile limit is straight from the GBA, unfortunately. Agb reserves tile 0 for the transparent tile as in games it's usually the most used. Hopefully in the future we'll be able to make this limitation more clear.

[rzru]

Thank you for the clarification!