From ae379df251969cfc5def2fbb8305c9a2ec46a378 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Jo=C3=A3o=20Magalh=C3=A3es?= <joamag@gmail.com>
Date: Mon, 11 Jul 2022 00:01:15 +0100
Subject: [PATCH] feat: support for 8x16 sprites/objects
---
CHANGELOG.md | 2 +-
examples/web/index.html | 2 +-
examples/web/index.ts | 21 +++++++++++++------
src/ppu.rs | 45 ++++++++++++++++++++++++++++++++++-------
4 files changed, 55 insertions(+), 15 deletions(-)
diff --git a/CHANGELOG.md b/CHANGELOG.md
index 2d4756df..d2425423 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -9,7 +9,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
### Added
-*
+* Support for 8x16 sprites
### Changed
diff --git a/examples/web/index.html b/examples/web/index.html
index 17dc8202..3000b3a8 100644
--- a/examples/web/index.html
+++ b/examples/web/index.html
@@ -69,7 +69,7 @@
<div id="separator-keyboard" class="separator" style="display: none;"></div>
<div id="section-debug" class="section" style="display: none;">
<div id="debug" class="debug">
- <canvas id="canvas-tiles" class="canvas-tiles" width="128" height="128"></canvas>
+ <canvas id="canvas-tiles" class="canvas-tiles" width="128" height="192"></canvas>
</div>
</div>
<div id="separator-debug" class="separator" style="display: none;"></div>
diff --git a/examples/web/index.ts b/examples/web/index.ts
index 8af69031..f2e4f018 100644
--- a/examples/web/index.ts
+++ b/examples/web/index.ts
@@ -541,9 +541,18 @@ const registerButtons = () => {
);
const videoBuff = new DataView(canvasImage.data.buffer);
- const drawSprite = (
+ /**
+ * Draws the tile at the given index to the proper
+ * vertical offset in the given context and buffer.
+ *
+ * @param index The index of the sprite to be drawn.
+ * @param format The pixel format of the sprite.
+ */
+ const drawTile = (
index: number,
- format: PixelFormat = PixelFormat.RGB
+ context: CanvasRenderingContext2D,
+ buffer: DataView,
+ format: PixelFormat = PixelFormat.RGB,
) => {
const pixels = state.gameBoy.get_tile_buffer(index);
const line = Math.floor(index / 16);
@@ -558,7 +567,7 @@ const registerButtons = () => {
(pixels[index + 1] << 16) |
(pixels[index + 2] << 8) |
(format == PixelFormat.RGBA ? pixels[index + 3] : 0xff);
- videoBuff.setUint32(offset, color);
+ buffer.setUint32(offset, color);
counter++;
if (counter == 8) {
@@ -568,11 +577,11 @@ const registerButtons = () => {
offset += PixelFormat.RGBA;
}
}
- canvasTilesCtx.putImageData(canvasImage, 0, 0);
+ context.putImageData(canvasImage, 0, 0);
};
- for (let index = 0; index < 256; index++) {
- drawSprite(index);
+ for (let index = 0; index < 384; index++) {
+ drawTile(index, canvasTilesCtx, videoBuff);
}
const vram = state.gameBoy.vram_eager();
diff --git a/src/ppu.rs b/src/ppu.rs
index 364ac835..14dcca66 100644
--- a/src/ppu.rs
+++ b/src/ppu.rs
@@ -16,6 +16,7 @@ pub const PALETTE_SIZE: usize = 4;
pub const RGB_SIZE: usize = 3;
pub const TILE_WIDTH: usize = 8;
pub const TILE_HEIGHT: usize = 8;
+pub const TILE_DOUBLE_HEIGHT: usize = 16;
/// The number of tiles that can be store in Game Boy's
/// VRAM memory according to specifications.
@@ -410,7 +411,7 @@ impl Ppu {
0x0040 => {
let value = if self.switch_bg { 0x01 } else { 0x00 }
| if self.switch_obj { 0x02 } else { 0x00 }
- | if self.obj_size { 0x02 } else { 0x00 }
+ | if self.obj_size { 0x04 } else { 0x00 }
| if self.bg_map { 0x08 } else { 0x00 }
| if self.bg_tile { 0x10 } else { 0x00 }
| if self.switch_window { 0x20 } else { 0x00 }
@@ -642,7 +643,7 @@ impl Ppu {
self.render_map(self.bg_map, self.scx, self.scy, 0, 0);
}
if self.switch_window {
- self.render_map(self.window_map, 0, 0, self.wx - 7, self.wy);
+ self.render_map(self.window_map, 0, 0, self.wx, self.wy);
}
if self.switch_obj {
self.render_objects();
@@ -704,7 +705,7 @@ impl Ppu {
// in case the current pixel to be drawn for the line
// is visible within the window draws it an increments
// the X coordinate of the tile
- if index as u8 >= wx {
+ if index as i16 >= wx as i16 - 7 {
// obtains the current pixel data from the tile and
// re-maps it according to the current palette
let pixel = self.tiles[tile_index].get(x, y);
@@ -757,11 +758,17 @@ impl Ppu {
// under iteration to be checked for drawing
let obj = self.obj_data[index];
+ let obj_height = if self.obj_size {
+ TILE_DOUBLE_HEIGHT
+ } else {
+ TILE_HEIGHT
+ };
+
// verifies if the sprite is currently located at the
// current line that is going to be drawn and skips it
// in case it's not
let is_contained =
- (obj.y <= self.ly as i16) && ((obj.y + TILE_HEIGHT as i16) > self.ly as i16);
+ (obj.y <= self.ly as i16) && ((obj.y + obj_height as i16) > self.ly as i16);
if !is_contained {
continue;
}
@@ -779,13 +786,37 @@ impl Ppu {
// point for the draw operation to be performed
let mut frame_offset = (self.ly as usize * DISPLAY_WIDTH + obj.x as usize) * RGB_SIZE;
- let tile_offset = self.ly as i16 - obj.y;
+ // the relative title offset should range from 0 to 7 in 8x8
+ // objects and from 0 to 15 in 8x16 objects
+ let mut tile_offset = self.ly as i16 - obj.y;
+
+ // saves some space for the reference to the tile that
+ // is going to be used in the current operation
+ let tile: &Tile;
+
+ // in case we're facing a 8x16 object and we must
+ // differentiate between the handling of the top tile
+ // and the bottom tile through bitwise manipulation
+ // of the tile index
+ if self.obj_size {
+ if tile_offset < 8 {
+ tile = &self.tiles[obj.tile as usize & 0xfe];
+ } else {
+ tile = &self.tiles[obj.tile as usize | 0x01];
+ tile_offset = tile_offset - 8;
+ }
+ }
+ // otherwise we're facing a 8x8 sprite and we should grab
+ // the tile directly from the object's tile index
+ else {
+ tile = &self.tiles[obj.tile as usize];
+ }
let tile_row: &[u8];
if obj.yflip {
- tile_row = self.tiles[obj.tile as usize].get_row((7 - tile_offset) as usize);
+ tile_row = tile.get_row((7 - tile_offset) as usize);
} else {
- tile_row = self.tiles[obj.tile as usize].get_row((tile_offset) as usize);
+ tile_row = tile.get_row((tile_offset) as usize);
}
for x in 0..TILE_WIDTH {
--
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