From cb035495307841506a8ca9105f4f9fe5ef3b44d4 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Jo=C3=A3o=20Magalh=C3=A3es?= <joamag@gmail.com>
Date: Sun, 4 Jun 2023 23:32:29 +0100
Subject: [PATCH] chore: made render for dmg only
---
frontends/sdl/Cargo.toml | 2 +
src/ppu.rs | 113 ++++++++++++++++++++++++++++++++++++++-
2 files changed, 113 insertions(+), 2 deletions(-)
diff --git a/frontends/sdl/Cargo.toml b/frontends/sdl/Cargo.toml
index 20ae6478..7d916f68 100644
--- a/frontends/sdl/Cargo.toml
+++ b/frontends/sdl/Cargo.toml
@@ -28,6 +28,8 @@ version = "0.4"
[dependencies.sdl2]
version = "0.35"
+git = "https://github.com/Rust-SDL2/rust-sdl2"
+rev = "27cd1fd67c811e06b9d997a77bb6089a1b65070d"
features = ["ttf", "image", "gfx", "mixer", "static-link", "use-vcpkg"]
# For MacOS running under arm64 architecture there may be linking issues
diff --git a/src/ppu.rs b/src/ppu.rs
index 7df9a923..996e9858 100644
--- a/src/ppu.rs
+++ b/src/ppu.rs
@@ -1069,16 +1069,124 @@ impl Ppu {
let switch_bg_window =
(self.gb_mode == GameBoyMode::Cgb && !self.dmg_compat) || self.switch_bg;
if switch_bg_window {
- self.render_map(self.bg_map, self.scx, self.scy, 0, 0, self.ly);
+ self.render_map_no_cgb(self.bg_map, self.scx, self.scy, 0, 0, self.ly);
}
if switch_bg_window && self.switch_window {
- self.render_map(self.window_map, 0, 0, self.wx, self.wy, self.window_counter);
+ self.render_map_no_cgb(self.window_map, 0, 0, self.wx, self.wy, self.window_counter);
}
if self.switch_obj {
self.render_objects();
}
}
+ fn render_map_no_cgb(&mut self, map: bool, scx: u8, scy: u8, wx: u8, wy: u8, ld: u8) {
+ // in case the target window Y position has not yet been reached
+ // then there's nothing to be done, returns control flow immediately
+ if self.ly < wy {
+ return;
+ }
+
+ // obtains the base address of the background map using the bg map flag
+ // that control which background map is going to be used
+ let map_offset: usize = if map { 0x1c00 } else { 0x1800 };
+
+ // calculates the map row index for the tile by using the current line
+ // index and the DY (scroll Y) divided by 8 (as the tiles are 8x8 pixels),
+ // on top of that ensures that the result is modulus 32 meaning that the
+ // drawing wraps around the Y axis
+ let row_index = (((ld as usize + scy as usize) & 0xff) >> 3) % 32;
+
+ // calculates the map offset by the row offset multiplied by the number
+ // of tiles in each row (32)
+ let row_offset = row_index * 32;
+
+ // calculates the sprite line offset by using the SCX register
+ // shifted by 3 meaning that the tiles are 8x8
+ let mut line_offset = (scx >> 3) as usize;
+
+ // calculates the index of the initial tile in drawing,
+ // if the tile data set in use is #1, the indexes are
+ // signed, then calculates a real tile offset
+ let mut tile_index = self.vram[map_offset + row_offset + line_offset] as usize;
+ if !self.bg_tile && tile_index < 128 {
+ tile_index += 256;
+ }
+
+ // obtains the reference to the tile that is going to be drawn
+ let mut tile = &self.tiles[tile_index];
+
+ // calculates the offset that is going to be used in the update of the color buffer
+ // which stores Game Boy colors from 0 to 3
+ let mut color_offset = self.ly as usize * DISPLAY_WIDTH;
+
+ // calculates the frame buffer offset position assuming the proper
+ // Game Boy screen width and RGB pixel (3 bytes) size
+ let mut frame_offset = self.ly as usize * DISPLAY_WIDTH * RGB_SIZE;
+
+ // calculates both the current Y and X positions within the tiles
+ // using the bitwise and operation as an effective modulus 8
+ let y = (ld as usize + scy as usize) & 0x07;
+ let mut x = (scx & 0x07) as usize;
+
+ // calculates the initial tile X position in drawing, doing this
+ // allows us to position the background map properly in the display
+ let initial_index = max(wx as i16 - 7, 0) as usize;
+ color_offset += initial_index;
+ frame_offset += initial_index * RGB_SIZE;
+
+ // iterates over all the pixels in the current line of the display
+ // to draw the background map, note that the initial index is used
+ // to skip the drawing of the tiles that are not visible (WX)
+ for _ in initial_index..DISPLAY_WIDTH {
+ // obtains the current pixel data from the tile and
+ // re-maps it according to the current palette
+ let pixel = tile.get(x, y);
+ let color = &self.palette_bg[pixel as usize];
+
+ // updates the pixel in the color buffer, which stores
+ // the raw pixel color information (unmapped)
+ self.color_buffer[color_offset] = pixel;
+
+ // set the color pixel in the frame buffer
+ self.frame_buffer[frame_offset] = color[0];
+ self.frame_buffer[frame_offset + 1] = color[1];
+ self.frame_buffer[frame_offset + 2] = color[2];
+
+ // increments the current tile X position in drawing
+ x += 1;
+
+ // in case the end of tile width has been reached then
+ // a new tile must be retrieved for rendering
+ if x == TILE_WIDTH {
+ // resets the tile X position to the base value
+ // as a new tile is going to be drawn
+ x = 0;
+
+ // calculates the new line tile offset making sure that
+ // the maximum of 32 is not overflown
+ line_offset = (line_offset + 1) % 32;
+
+ // calculates the tile index and makes sure the value
+ // takes into consideration the bg tile value
+ tile_index = self.vram[map_offset + row_offset + line_offset] as usize;
+ if !self.bg_tile && tile_index < 128 {
+ tile_index += 256;
+ }
+
+ // obtains the reference to the new tile in drawing
+ tile = &self.tiles[tile_index];
+ }
+
+ // increments the color offset by one, representing
+ // the drawing of one pixel
+ color_offset += 1;
+
+ // increments the offset of the frame buffer by the
+ // size of an RGB pixel (which is 3 bytes)
+ frame_offset += RGB_SIZE;
+ }
+ }
+
fn render_map(&mut self, map: bool, scx: u8, scy: u8, wx: u8, wy: u8, ld: u8) {
// in case the target window Y position has not yet been reached
// then there's nothing to be done, returns control flow immediately
@@ -1088,6 +1196,7 @@ impl Ppu {
// selects the correct background attributes map based on the bg map flag
// because the attributes are separated according to the map they represent
+ // this is only relevant for CGB mode
let bg_map_attrs = if map {
self.bg_map_attrs_1
} else {
--
GitLab