IMAGES: Add support for swizzled Xbox SBM images

Unfortunately, there's no way to tell from the image data alone whether an SBM is swizzled, so the image decoder needs to be told.
xoreos · Jul 29, 2018 · 06b5f17 · 06b5f17
1 parent c8bc2ff
commit 06b5f17
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Showing 2 changed files with 19 additions and 14 deletions.
diff --git a/src/images/sbm.cpp b/src/images/sbm.cpp
@@ -33,19 +33,19 @@
 
 namespace Images {
 
-SBM::SBM(Common::SeekableReadStream &sbm) {
+SBM::SBM(Common::SeekableReadStream &sbm, bool deswizzle) {
 	_format = kPixelFormatB8G8R8A8;
 
-	load(sbm);
+	load(sbm, deswizzle);
 }
 
 SBM::~SBM() {
 }
 
-void SBM::load(Common::SeekableReadStream &sbm) {
+void SBM::load(Common::SeekableReadStream &sbm, bool deswizzle) {
 	try {
 
-		readData(sbm);
+		readData(sbm, deswizzle);
 
 	} catch (Common::Exception &e) {
 		e.add("Failed reading SBM file");
@@ -56,11 +56,11 @@ void SBM::load(Common::SeekableReadStream &sbm) {
 	::Images::flipVertically(_mipMaps[0]->data.get(), _mipMaps[0]->width, _mipMaps[0]->height, 4);
 }
 
-void SBM::readData(Common::SeekableReadStream &sbm) {
+void SBM::readData(Common::SeekableReadStream &sbm, bool deswizzle) {
 	if ((sbm.size() % 1024) != 0)
 		throw Common::Exception("Invalid SBM (%u)", (uint)sbm.size());
 
-	size_t rowCount = (sbm.size() / 1024);
+	const size_t rowCount = (sbm.size() / 1024);
 
 	_mipMaps.push_back(new MipMap);
 
@@ -75,8 +75,8 @@ void SBM::readData(Common::SeekableReadStream &sbm) {
 	// coordinates but different planes.
 	// We'll unpack them and draw them next to each other instead.
 
-	int masks [4] = { 0x03, 0x0C, 0x30, 0xC0 };
-	int shifts[4] = {    0,    2,    4,    6 };
+	static const int masks [4] = { 0x03, 0x0C, 0x30, 0xC0 };
+	static const int shifts[4] = {    0,    2,    4,    6 };
 
 	byte *data = _mipMaps[0]->data.get();
 	byte buffer[1024];
@@ -86,11 +86,11 @@ void SBM::readData(Common::SeekableReadStream &sbm) {
 			throw Common::Exception(Common::kReadError);
 
 		for (int y = 0; y < 32; y++) {
-			byte *src = buffer + y * 32;
-
 			for (int plane = 0; plane < 4; plane++) {
 				for (int x = 0; x < 32; x++) {
-					byte a = ((src[x] & masks[plane]) >> shifts[plane]) * 0x55;
+					const uint32 offset = deswizzle ? deSwizzleOffset(x, y, 32, rowCount) : (y * 32 + x);
+
+					const byte a = ((buffer[offset] & masks[plane]) >> shifts[plane]) * 0x55;
 
 					*data++ = 0xFF; // B
 					*data++ = 0xFF; // G

diff --git a/src/images/sbm.h b/src/images/sbm.h
@@ -39,13 +39,18 @@ namespace Images {
  */
 class SBM : public Decoder {
 public:
-	SBM(Common::SeekableReadStream &sbm);
+	/** Read an SBM image out of a stream.
+	 *
+	 *  @param The stream to read out of.
+	 *  @param deswizzle This is an Xbox SBM that has swizzled data.
+	 */
+	SBM(Common::SeekableReadStream &sbm, bool deswizzle = false);
 	~SBM();
 
 private:
 	// Loading helpers
-	void load(Common::SeekableReadStream &sbm);
-	void readData(Common::SeekableReadStream &sbm);
+	void load(Common::SeekableReadStream &sbm, bool deswizzle);
+	void readData(Common::SeekableReadStream &sbm, bool deswizzle);
 };
 
 } // End of namespace Images