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chore(ppu): improve bg-sprite priority functionality

This commit is contained in:
Rekai Nyangadzayi Musuka 2021-10-20 20:07:14 -03:00
parent de8fe1a367
commit 4cfd951ede
1 changed files with 24 additions and 28 deletions
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52
src/ppu.rs
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@ -430,43 +430,39 @@ impl Ppu {
}
fn clock_fifo(&mut self) -> Option<GrayShade> {
use ObjectPaletteKind::*;
use RenderPriority::*;
let obj_palette_0 = &self.monochrome.obj_palette_0;
let obj_palette_1 = &self.monochrome.obj_palette_1;
match self.fifo.back.pop_front() {
Some(bg_pixel) => match self.fifo.obj.pop_front() {
Some(obj_pixel) => match obj_pixel.priority {
Object | BackgroundAndWindow if obj_pixel.shade_id == 0 => {
Some(self.bg_pixel(bg_pixel.shade_id))
}
BackgroundAndWindow if bg_pixel.shade_id != 0 => {
Some(self.bg_pixel(bg_pixel.shade_id))
}
Object | BackgroundAndWindow => {
let maybe_sprite = match obj_pixel.palette_kind {
Zero => obj_palette_0.shade(obj_pixel.shade_id),
One => obj_palette_1.shade(obj_pixel.shade_id),
};
let sprite = maybe_sprite
.expect("Sprite w/ a colour id of 0 has already been handled");
Some(sprite)
}
self.fifo
.back
.pop_front()
.map(|bg| match self.fifo.obj.pop_front() {
Some(obj) => match obj.priority {
_ if obj.shade_id == 0 => self.bg_pixel(bg),
BackgroundAndWindow if bg.shade_id != 0 => self.bg_pixel(bg),
_ => self.obj_pixel(obj),
},
_ => Some(self.bg_pixel(bg_pixel.shade_id)),
},
None => None,
None => self.bg_pixel(bg),
})
}
fn obj_pixel(&self, obj: ObjPixelProperty) -> GrayShade {
use ObjectPaletteKind::*;
assert!(obj.shade_id != 0);
let p0 = &self.monochrome.obj_palette_0;
let p1 = &self.monochrome.obj_palette_1;
match obj.palette_kind {
Zero => p0.shade(obj.shade_id).expect("Object shade id is non-zero"),
One => p1.shade(obj.shade_id).expect("Object shade id is non-zero"),
}
}
fn bg_pixel(&self, shade_id: u8) -> GrayShade {
fn bg_pixel(&self, bg: BgPixelProperty) -> GrayShade {
let bg_palette = &self.monochrome.bg_palette;
if self.ctrl.bg_win_enabled() {
bg_palette.shade(shade_id)
bg_palette.shade(bg.shade_id)
} else {
bg_palette.shade(0)
}