From e61d4647b5757a16751c712cb411dd6255c95a8b Mon Sep 17 00:00:00 2001
From: Gary Talent <gary@drinkingtea.net>
Date: Mon, 28 Jul 2025 21:54:50 -0500
Subject: [PATCH] [nostalgia/gfx] Fix BG tilesheet loading, add background
 offset functions

---
 .../modules/gfx/include/nostalgia/gfx/gfx.hpp |  8 ++++++--
 src/nostalgia/modules/gfx/src/gfx-gba.cpp     | 20 +++++++++++++------
 src/nostalgia/modules/gfx/src/gfx.cpp         |  2 +-
 3 files changed, 21 insertions(+), 9 deletions(-)

diff --git a/src/nostalgia/modules/gfx/include/nostalgia/gfx/gfx.hpp b/src/nostalgia/modules/gfx/include/nostalgia/gfx/gfx.hpp
index 978c0a96..792bd822 100644
--- a/src/nostalgia/modules/gfx/include/nostalgia/gfx/gfx.hpp
+++ b/src/nostalgia/modules/gfx/include/nostalgia/gfx/gfx.hpp
@@ -238,6 +238,10 @@ void setBgCbb(Context &ctx, unsigned bgIdx, unsigned cbbIdx) noexcept;
 
 void setBgPriority(Context &ctx, uint_t bgIdx, uint_t priority) noexcept;
 
+void setBgOffset(Context &ctx, uint16_t bg, int16_t x, int16_t y) noexcept;
+
+void scrollBgOffset(Context &ctx, uint16_t bg, int16_t x, int16_t y) noexcept;
+
 void hideSprite(Context &ctx, unsigned) noexcept;
 
 void showSprite(Context &ctx, unsigned) noexcept;
@@ -260,8 +264,8 @@ constexpr ox::CStringView GlslVersion = "#version 330";
 [[nodiscard]]
 ox::Size drawSize(int scale = 5) noexcept;
 
-void draw(gfx::Context &ctx, ox::Size const &renderSz) noexcept;
+void draw(Context &ctx, ox::Size const &renderSz) noexcept;
 
-void draw(gfx::Context&, int scale = 5) noexcept;
+void draw(Context&, int scale = 5) noexcept;
 
 }
diff --git a/src/nostalgia/modules/gfx/src/gfx-gba.cpp b/src/nostalgia/modules/gfx/src/gfx-gba.cpp
index ad67b35b..bb6ad6f1 100644
--- a/src/nostalgia/modules/gfx/src/gfx-gba.cpp
+++ b/src/nostalgia/modules/gfx/src/gfx-gba.cpp
@@ -169,8 +169,8 @@ ox::Error loadBgTileSheet(
 		unsigned const cbb,
 		CompactTileSheet const &ts,
 		ox::Optional<unsigned> const &paletteBank) noexcept {
-	auto const cnt = (ts.pixels.size() * PixelsPerTile) / (1 + (ts.bpp == 4));
-	for (size_t i = 0; i < cnt; ++i) {
+	auto const cnt = ts.pixels.size() >> (ts.bpp == 4);
+	for (size_t i{}; i < cnt; ++i) {
 		auto const srcIdx = i * 2;
 		auto const p1 = static_cast<uint16_t>(ts.pixels[srcIdx]);
 		auto const p2 = static_cast<uint16_t>(ts.pixels[srcIdx + 1]);
@@ -218,10 +218,10 @@ ox::Error loadSpriteTileSheet(
 		Context &ctx,
 		CompactTileSheet const &ts,
 		bool const loadDefaultPalette) noexcept {
-	for (size_t i = 0; i < ts.pixels.size(); i += 2) {
-		uint16_t v = ts.pixels[i];
-		v |= static_cast<uint16_t>(ts.pixels[i + 1] << 8);
-		MEM_SPRITE_TILES[i] = v;
+	for (size_t i{}; i < ts.pixels.size(); i += 2) {
+		MEM_SPRITE_TILES[i >> 1] =
+			static_cast<uint16_t>(ts.pixels[i]) |
+			(static_cast<uint16_t>(ts.pixels[i + 1]) << 8);
 	}
 	if (loadDefaultPalette && ts.defaultPalette) {
 		OX_RETURN_ERROR(loadSpritePalette(ctx, ts.defaultPalette));
@@ -294,6 +294,14 @@ void setBgPriority(Context&, uint_t const bgIdx, uint_t const priority) noexcept
 	bgCtl = (bgCtl & 0b1111'1111'1111'1100u) | (priority & 0b11);
 }
 
+void setBgOffset(Context&, uint16_t const bg, int16_t const x, int16_t const y) noexcept {
+	teagba::setBgOffset(bg, x, y);
+}
+
+void scrollBgOffset(Context&, uint16_t const bg, int16_t const x, int16_t const y) noexcept {
+	teagba::scrollBgOffset(bg, x, y);
+}
+
 void hideSprite(Context&, unsigned const idx) noexcept {
 	//oxAssert(g_spriteUpdates < config::GbaSpriteBufferLen, "Sprite update buffer overflow");
 	teagba::addSpriteUpdate({
diff --git a/src/nostalgia/modules/gfx/src/gfx.cpp b/src/nostalgia/modules/gfx/src/gfx.cpp
index e52ac87b..4c93a2c2 100644
--- a/src/nostalgia/modules/gfx/src/gfx.cpp
+++ b/src/nostalgia/modules/gfx/src/gfx.cpp
@@ -249,7 +249,7 @@ void setBgTile(
 }
 
 ox::Error initConsole(Context &ctx) noexcept {
-	constexpr ox::FileAddress TilesheetAddr = ox::StringLiteral("/TileSheets/Charset.ng");
+	constexpr ox::FileAddress TilesheetAddr = ox::StringLiteral("/TileSheets/Charset.nts");
 	constexpr ox::FileAddress PaletteAddr = ox::StringLiteral("/Palettes/Charset.npal");
 	setBgStatus(ctx, 0b0001);
 	setBgCbb(ctx, 0, 0);