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chore(ppu): reimplement offset calculation for obj fetcher

This commit is contained in:
Rekai Nyangadzayi Musuka 2021-05-04 22:11:03 -05:00
parent 6f919acafb
commit 2a7377c724
1 changed files with 8 additions and 10 deletions
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18
src/ppu.rs
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@ -691,10 +691,10 @@ impl PixelFetcher {
TileDataAddress::X8000 => 0x8000 + (id as u16 * 16),
};
let offset = if window {
2 * (self.bg.window_line.count() % 8)
let offset = 2 * if window {
self.bg.window_line.count() % 8
} else {
2 * ((line_y + scroll_y) % 8)
(line_y + scroll_y) % 8
};
tile_data_addr + offset as u16
@ -724,17 +724,15 @@ impl PixelFetcher {
pub fn get_obj_low_addr(attr: &ObjectAttribute, pos: &ScreenPosition, obj_size: u8) -> u16 {
let line_y = pos.line_y;
let scroll_y = pos.scroll_y;
// FIXME: Should we subtract 16 from attr.y?
let y = attr.y.wrapping_sub(16);
let line = if attr.flags.y_flip() {
obj_size - (line_y - y)
let offset = 2 * if attr.flags.y_flip() {
obj_size - (line_y + scroll_y) % 8
} else {
line_y - y
(line_y + scroll_y) % 8
};
0x8000 + (attr.tile_index as u16 * 16) + (line as u16 * 2)
0x8000 + (attr.tile_index as u16 * 16) + offset as u16
}
}