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fix: resolve issues with sprite mirroring

This commit is contained in:
Rekai Nyangadzayi Musuka 2022-03-11 22:40:47 -04:00
parent 05e67da181
commit c4a2a1a865
1 changed files with 8 additions and 34 deletions
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42
src/ppu.zig
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@ -142,57 +142,31 @@ pub const Ppu = struct {
} else break;
}
// // TODO: Scanning OAM for every single pixel is insanely expensive
// // This should be done once per scanline (and then check for X bounds every pixel)
// var j: u32 = 0;
// while (j < self.oam.buf.len) : (j += 8) {
// // Attributes in OAM are 6 bytes long, with 2 bytes of padding
// // Grab Attributes from OAM
// const attr0 = @bitCast(Attr0, self.oam.get16(j));
// const attr1 = @bitCast(Attr1, self.oam.get16(j + 2));
// const attr2 = @bitCast(Attr2, self.oam.get16(j + 4));
// // Only consider enabled sprites on the current priority
// if (attr0.disabled.read() or attr2.rel_prio.read() != prio) continue;
// // Determine sprite bounds
// const d = spriteDimensions(attr0.shape.read(), attr1.size.read());
// const sy = attr0.y.read();
// const sx = attr1.x.read();
// const sx_end = sx + d[0];
// const sy_end = sy + d[1];
// // If sprite is in range
// if (sy < y and sy_end > y and sx < x and sx_end > x) {
// maybe_sprite = Sprite.init(attr0, attr1, attr2);
// break;
// }
// }
// If we didn't find a sprite, progress to the next pixel
const sprite: Sprite = if (maybe_sprite) |s| s else continue;
const is_8bpp = sprite.is_8bpp();
// Y and X coordinates within the context of a singular 8x8 tile
const tile_y = y - sprite.y();
const tile_x = x - sprite.x();
const tile_y: u16 = (y - sprite.y()) ^ if (sprite.v_flip()) (sprite.height - 1) else 0;
const tile_x = (x - sprite.x()) ^ if (sprite.h_flip()) (sprite.width - 1) else 0;
const tile_id: u32 = sprite.tile_id();
const tile_row_offset: u32 = if (is_8bpp) 8 else 4;
const tile_len: u32 = if (is_8bpp) 0x40 else 0x20;
const row = if (sprite.v_flip()) 7 - (tile_y % 8) else tile_y % 8;
const col = if (sprite.h_flip()) 7 - (tile_x % 8) else tile_x % 8;
const row = tile_y % 8;
const col = tile_x % 8;
const tile_base: u32 = char_base + (0x20 * tile_id) + (tile_row_offset * row) + if (is_8bpp) col else col / 2;
var tile_offset = (tile_x >> 3) * tile_len;
var tile_offset = (tile_x / 8) * tile_len;
if (self.dispcnt.obj_mapping.read()) {
// One Dimensional
tile_offset += (tile_y / 8) * tile_len * (sprite.width >> 3);
tile_offset += (tile_y / 8) * tile_len * (sprite.width / 8);
} else {
// Two Dimensional
tile_offset += (@as(u32, tile_y) >> 3) * tile_len * 0x20;
// TODO: This doesn't work
tile_offset += (tile_y / 8) * tile_len * 0x20;
}
const tile = self.vram.buf[tile_base + tile_offset];