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fix: horizontally flip ppu so the Nin***** logo is readable

This commit is contained in:
Rekai Nyangadzayi Musuka 2021-03-20 23:24:06 -05:00
parent 7462061937
commit c64417fdce
1 changed files with 16 additions and 15 deletions
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31
src/ppu.rs
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@ -98,24 +98,27 @@ impl Ppu {
fn draw_scanline(&mut self) { fn draw_scanline(&mut self) {
let mut scanline: [u8; GB_WIDTH * 4] = [0; GB_WIDTH * 4]; let mut scanline: [u8; GB_WIDTH * 4] = [0; GB_WIDTH * 4];
let scroll_y = self.pos.scroll_y;
let scroll_x = self.pos.scroll_x;
// let window_y = self.pos.window_y;
// let window_x = self.pos.window_x - 7;
let tile_map_addr = match self.lcd_control.bg_tile_map_addr() { let tile_map_addr = match self.lcd_control.bg_tile_map_addr() {
TileMapAddress::X9800 => 0x9800, TileMapAddress::X9800 => 0x9800,
TileMapAddress::X9C00 => 0x9C00, TileMapAddress::X9C00 => 0x9C00,
}; };
let y_pos: u16 = scroll_y as u16 + self.pos.line_y as u16; let y_pos = self.pos.line_y as u16 + self.pos.scroll_y as u16;
let tile_row: u16 = (y_pos as u16 / 8) * 32;
for (i, chunk) in scanline.chunks_mut(4).enumerate() { // There are always 20 rows of tiles in the LCD Viewport
let x_pos = i as u8 + scroll_x; // 160 / 20 = 8, so we can figure out the row of a tile with the following
let tile_row: u16 = y_pos as u16 / 8;
for (line_x, chunk) in scanline.chunks_mut(4).enumerate() {
let x_pos = line_x as u16 + self.pos.scroll_x as u16;
// There are always 18 columns of tiles in the LCD Viewport
// 144 / 18 = 8, so we can figure out the column of a tile with the following
let tile_column = x_pos / 8; let tile_column = x_pos / 8;
let tile_addr = tile_map_addr + tile_row as u16 + tile_column as u16; // A tile is 8 x 8, and any given pixel in a tile comes from two bytes
// so the size of a tile is (8 + 8) * 2 which is 32
let tile_addr = tile_map_addr + (tile_row * 32) as u16 + tile_column as u16;
let tile_number = self.read_byte(tile_addr); let tile_number = self.read_byte(tile_addr);
let tile_data_addr = match self.lcd_control.tile_data_addr() { let tile_data_addr = match self.lcd_control.tile_data_addr() {
@ -128,13 +131,11 @@ impl Ppu {
let higher = self.read_byte(tile_data_addr + line as u16); let higher = self.read_byte(tile_data_addr + line as u16);
let lower = self.read_byte(tile_data_addr + line as u16 + 1); let lower = self.read_byte(tile_data_addr + line as u16 + 1);
let pixels = Pixels::from_bytes(higher, lower); let pixels = Pixels::from_bytes(higher, lower);
// println!("Hi: {:#010b} | Lo: {:#010b}", higher, lower);
let bit = x_pos % 8; let bit = x_pos as usize % 8;
let palette = self.monochrome.bg_palette; let palette = self.monochrome.bg_palette;
let shade = palette.colour(pixels.colour_id(bit)); let shade = palette.colour(pixels.pixel(7 - bit)); // Flip Horizontally
chunk.copy_from_slice(&shade.into_rgba()); chunk.copy_from_slice(&shade.into_rgba());
} }
@ -530,7 +531,7 @@ impl Pixels {
Self([higher, lower]) Self([higher, lower])
} }
pub fn colour_id(&self, bit: u8) -> u8 { pub fn pixel(&self, bit: usize) -> u8 {
let higher = &self.0[0] >> bit; let higher = &self.0[0] >> bit;
let lower = &self.0[1] >> bit; let lower = &self.0[1] >> bit;