Merge pull request #103276 from BlueCube3310/bcdec-alignment-fix

bcdec: Fix decompressing mipmaps of non-power of 2 textures

modules/bcdec/image_decompress_bcdec.cpp

@@ -44,110 +44,174 @@ inline void bcdec_bc6h_half_u(const void *compressedBlock, void *decompressedBlo
 	bcdec_bc6h_half(compressedBlock, decompressedBlock, destinationPitch, false);
 }
 
-static void decompress_image(BCdecFormat format, const void *src, void *dst, const uint64_t width, const uint64_t height) {
-	const uint8_t *src_blocks = reinterpret_cast<const uint8_t *>(src);
-	uint8_t *dec_blocks = reinterpret_cast<uint8_t *>(dst);
+template <void (*decompress_func)(const void *, void *, int), int block_size, int pixel_size, int component_size>
+static inline void _safe_decompress_mipmap(int width, int height, const uint8_t *src, uint8_t *dst) {
+	// A stack-allocated output buffer large enough to contain an entire uncompressed block.
+	uint8_t temp_buf[4 * 4 * pixel_size];
+
+	// The amount of misaligned pixels on each axis.
+	const int width_diff = width - (width & ~0x03);
+	const int height_diff = height - (height & ~0x03);
+
+	// The amount of uncompressed blocks on each axis.
+	const int width_blocks = (width & ~0x03) / 4;
+	const int height_blocks = (height & ~0x03) / 4;
+
+	// The pitch of the image in bytes.
+	const int image_pitch = width * pixel_size;
+	// The pitch of a block in bytes.
+	const int block_pitch = 4 * pixel_size;
+	// The pitch of the last block in bytes.
+	const int odd_pitch = width_diff * pixel_size;
+
+	size_t src_pos = 0;
+	size_t dst_pos = 0;
+
+	// Decompress the blocks, starting from the top.
+	for (int y = 0; y < height_blocks; y += 1) {
+		// Decompress the blocks, starting from the left.
+		for (int x = 0; x < width_blocks; x += 1) {
+			decompress_func(&src[src_pos], &dst[dst_pos], image_pitch / component_size);
+			src_pos += block_size;
+			dst_pos += block_pitch;
+		}
+
+		// Decompress the block on the right.
+		if (width_diff > 0) {
+			decompress_func(&src[src_pos], temp_buf, block_pitch / component_size);
+
+			// Copy the data from the temporary buffer to the output.
+			for (int i = 0; i < 4; i++) {
+				memcpy(&dst[dst_pos + i * image_pitch], &temp_buf[i * block_pitch], odd_pitch);
+			}
+
+			src_pos += block_size;
+			dst_pos += odd_pitch;
+		}
+
+		// Skip to the next row of blocks, the current one has already been filled.
+		dst_pos += 3 * image_pitch;
+	}
+
+	// Decompress the blocks at the bottom of the image.
+	if (height_diff > 0) {
+		// Decompress the blocks at the bottom.
+		for (int x = 0; x < width_blocks; x += 1) {
+			decompress_func(&src[src_pos], temp_buf, block_pitch / component_size);
+
+			// Copy the data from the temporary buffer to the output.
+			for (int i = 0; i < height_diff; i++) {
+				memcpy(&dst[dst_pos + i * image_pitch], &temp_buf[i * block_pitch], block_pitch);
+			}
+
+			src_pos += block_size;
+			dst_pos += block_pitch;
+		}
+
+		// Decompress the block in the lower-right corner.
+		if (width_diff > 0) {
+			decompress_func(&src[src_pos], temp_buf, block_pitch / component_size);
+
+			// Copy the data from the temporary buffer to the output.
+			for (int i = 0; i < height_diff; i++) {
+				memcpy(&dst[dst_pos + i * image_pitch], &temp_buf[i * block_pitch], odd_pitch);
+			}
 
-#define DECOMPRESS_LOOP(func, block_size, color_bytesize, color_components)             \
-	for (uint64_t y = 0; y < height; y += 4) {                                          \
-		for (uint64_t x = 0; x < width; x += 4) {                                       \
-			func(&src_blocks[src_pos], &dec_blocks[dst_pos], width * color_components); \
-			src_pos += block_size;                                                      \
-			dst_pos += 4 * color_bytesize;                                              \
-		}                                                                               \
-		dst_pos += 3 * width * color_bytesize;                                          \
+			src_pos += block_size;
+			dst_pos += odd_pitch;
+		}
 	}
+}
+
+template <void (*decompress_func)(const void *, void *, int), int block_size, int pixel_size, int component_size>
+static inline void _decompress_mipmap(int width, int height, const uint8_t *src, uint8_t *dst) {
+	size_t src_pos = 0;
+	size_t dst_pos = 0;
+
+	// The size of a single block in bytes.
+	const int block_pitch = 4 * pixel_size;
+	// The pitch of the image in bytes.
+	const int image_pitch = width * pixel_size;
+
+	for (int y = 0; y < height; y += 4) {
+		for (int x = 0; x < width; x += 4) {
+			decompress_func(&src[src_pos], &dst[dst_pos], image_pitch / component_size);
+			src_pos += block_size;
+			dst_pos += block_pitch;
+		}
 
-#define DECOMPRESS_LOOP_SAFE(func, block_size, color_bytesize, color_components, output)                                                              \
-	for (uint64_t y = 0; y < height; y += 4) {                                                                                                        \
-		for (uint64_t x = 0; x < width; x += 4) {                                                                                                     \
-			const uint32_t yblock = MIN(height - y, 4ul);                                                                                             \
-			const uint32_t xblock = MIN(width - x, 4ul);                                                                                              \
-                                                                                                                                                      \
-			const bool incomplete = yblock < 4 || xblock < 4;                                                                                         \
-			uint8_t *dec_out = incomplete ? output : &dec_blocks[y * 4 * width + x * color_bytesize];                                                 \
-                                                                                                                                                      \
-			func(&src_blocks[src_pos], dec_out, 4 * color_components);                                                                                \
-			src_pos += block_size;                                                                                                                    \
-                                                                                                                                                      \
-			if (incomplete) {                                                                                                                         \
-				for (uint32_t cy = 0; cy < yblock; cy++) {                                                                                            \
-					for (uint32_t cx = 0; cx < xblock; cx++) {                                                                                        \
-						memcpy(&dec_blocks[(y + cy) * 4 * width + (x + cx) * color_bytesize], &output[cy * 4 + cx * color_bytesize], color_bytesize); \
-					}                                                                                                                                 \
-				}                                                                                                                                     \
-			}                                                                                                                                         \
-		}                                                                                                                                             \
+		// Skip to the next row of blocks, the current one has already been filled.
+		dst_pos += 3 * image_pitch;
 	}
+}
 
-	if (width % 4 != 0 || height % 4 != 0) {
-		uint64_t src_pos = 0;
+static void decompress_image(BCdecFormat format, const void *src, void *dst, const uint64_t width, const uint64_t height) {
+	const uint8_t *src_blocks = reinterpret_cast<const uint8_t *>(src);
+	uint8_t *dec_blocks = reinterpret_cast<uint8_t *>(dst);
 
-		uint8_t r8_output[4 * 4];
-		uint8_t rg8_output[4 * 4 * 2];
-		uint8_t rgba8_output[4 * 4 * 4];
-		uint8_t rgbh_output[4 * 4 * 6];
+	const uint64_t aligned_width = (width + 3) & ~0x03;
+	const uint64_t aligned_height = (height + 3) & ~0x03;
 
+	if (width != aligned_width || height != aligned_height) {
+		// Decompress the mipmap in a 'safe' way, which involves starting from the top left.
+		// For each block row, decompress all of the 'full' blocks, then the misaligned one (on the x axis).
+		// Then, decompress the final misaligned block row at the bottom.
+		// Finally, decompress the misaligned block at the bottom right.
 		switch (format) {
 			case BCdec_BC1: {
-				DECOMPRESS_LOOP_SAFE(bcdec_bc1, BCDEC_BC1_BLOCK_SIZE, 4, 4, rgba8_output)
+				_safe_decompress_mipmap<bcdec_bc1, BCDEC_BC1_BLOCK_SIZE, 4, 1>(width, height, src_blocks, dec_blocks);
 			} break;
 			case BCdec_BC2: {
-				DECOMPRESS_LOOP_SAFE(bcdec_bc2, BCDEC_BC2_BLOCK_SIZE, 4, 4, rgba8_output)
+				_safe_decompress_mipmap<bcdec_bc2, BCDEC_BC2_BLOCK_SIZE, 4, 1>(width, height, src_blocks, dec_blocks);
 			} break;
 			case BCdec_BC3: {
-				DECOMPRESS_LOOP_SAFE(bcdec_bc3, BCDEC_BC3_BLOCK_SIZE, 4, 4, rgba8_output)
+				_safe_decompress_mipmap<bcdec_bc3, BCDEC_BC3_BLOCK_SIZE, 4, 1>(width, height, src_blocks, dec_blocks);
 			} break;
 			case BCdec_BC4: {
-				DECOMPRESS_LOOP_SAFE(bcdec_bc4, BCDEC_BC4_BLOCK_SIZE, 1, 1, r8_output)
+				_safe_decompress_mipmap<bcdec_bc4, BCDEC_BC4_BLOCK_SIZE, 1, 1>(width, height, src_blocks, dec_blocks);
 			} break;
 			case BCdec_BC5: {
-				DECOMPRESS_LOOP_SAFE(bcdec_bc5, BCDEC_BC5_BLOCK_SIZE, 2, 2, rg8_output)
+				_safe_decompress_mipmap<bcdec_bc5, BCDEC_BC5_BLOCK_SIZE, 2, 1>(width, height, src_blocks, dec_blocks);
 			} break;
 			case BCdec_BC6U: {
-				DECOMPRESS_LOOP_SAFE(bcdec_bc6h_half_u, BCDEC_BC6H_BLOCK_SIZE, 6, 3, rgbh_output)
+				_safe_decompress_mipmap<bcdec_bc6h_half_u, BCDEC_BC6H_BLOCK_SIZE, 6, 2>(width, height, src_blocks, dec_blocks);
 			} break;
 			case BCdec_BC6S: {
-				DECOMPRESS_LOOP_SAFE(bcdec_bc6h_half_s, BCDEC_BC6H_BLOCK_SIZE, 6, 3, rgbh_output)
+				_safe_decompress_mipmap<bcdec_bc6h_half_s, BCDEC_BC6H_BLOCK_SIZE, 6, 2>(width, height, src_blocks, dec_blocks);
 			} break;
 			case BCdec_BC7: {
-				DECOMPRESS_LOOP_SAFE(bcdec_bc7, BCDEC_BC7_BLOCK_SIZE, 4, 4, rgba8_output)
+				_safe_decompress_mipmap<bcdec_bc7, BCDEC_BC7_BLOCK_SIZE, 4, 1>(width, height, src_blocks, dec_blocks);
 			} break;
 		}
-
 	} else {
-		uint64_t src_pos = 0, dst_pos = 0;
-
+		// Just decompress as usual, as fast as possible.
 		switch (format) {
 			case BCdec_BC1: {
-				DECOMPRESS_LOOP(bcdec_bc1, BCDEC_BC1_BLOCK_SIZE, 4, 4)
+				_decompress_mipmap<bcdec_bc1, BCDEC_BC1_BLOCK_SIZE, 4, 1>(width, height, src_blocks, dec_blocks);
 			} break;
 			case BCdec_BC2: {
-				DECOMPRESS_LOOP(bcdec_bc2, BCDEC_BC2_BLOCK_SIZE, 4, 4)
+				_decompress_mipmap<bcdec_bc2, BCDEC_BC2_BLOCK_SIZE, 4, 1>(width, height, src_blocks, dec_blocks);
 			} break;
 			case BCdec_BC3: {
-				DECOMPRESS_LOOP(bcdec_bc3, BCDEC_BC3_BLOCK_SIZE, 4, 4)
+				_decompress_mipmap<bcdec_bc3, BCDEC_BC3_BLOCK_SIZE, 4, 1>(width, height, src_blocks, dec_blocks);
 			} break;
 			case BCdec_BC4: {
-				DECOMPRESS_LOOP(bcdec_bc4, BCDEC_BC4_BLOCK_SIZE, 1, 1)
+				_decompress_mipmap<bcdec_bc4, BCDEC_BC4_BLOCK_SIZE, 1, 1>(width, height, src_blocks, dec_blocks);
 			} break;
 			case BCdec_BC5: {
-				DECOMPRESS_LOOP(bcdec_bc5, BCDEC_BC5_BLOCK_SIZE, 2, 2)
+				_decompress_mipmap<bcdec_bc5, BCDEC_BC5_BLOCK_SIZE, 2, 1>(width, height, src_blocks, dec_blocks);
 			} break;
 			case BCdec_BC6U: {
-				DECOMPRESS_LOOP(bcdec_bc6h_half_u, BCDEC_BC6H_BLOCK_SIZE, 6, 3)
+				_decompress_mipmap<bcdec_bc6h_half_u, BCDEC_BC6H_BLOCK_SIZE, 6, 2>(width, height, src_blocks, dec_blocks);
 			} break;
 			case BCdec_BC6S: {
-				DECOMPRESS_LOOP(bcdec_bc6h_half_s, BCDEC_BC6H_BLOCK_SIZE, 6, 3)
+				_decompress_mipmap<bcdec_bc6h_half_s, BCDEC_BC6H_BLOCK_SIZE, 6, 2>(width, height, src_blocks, dec_blocks);
 			} break;
 			case BCdec_BC7: {
-				DECOMPRESS_LOOP(bcdec_bc7, BCDEC_BC7_BLOCK_SIZE, 4, 4)
+				_decompress_mipmap<bcdec_bc7, BCDEC_BC7_BLOCK_SIZE, 4, 1>(width, height, src_blocks, dec_blocks);
 			} break;
 		}
 	}
-
-#undef DECOMPRESS_LOOP
-#undef DECOMPRESS_LOOP_SAFE
 }
 
 void image_decompress_bcdec(Image *p_image) {
@@ -156,21 +220,6 @@ void image_decompress_bcdec(Image *p_image) {
 	int width = p_image->get_width();
 	int height = p_image->get_height();
 
-	// Compressed images' dimensions should be padded to the upper multiple of 4.
-	// If they aren't, they need to be realigned (the actual data is correctly padded though).
-	const bool need_width_realign = width % 4 != 0;
-	const bool need_height_realign = height % 4 != 0;
-
-	if (need_width_realign || need_height_realign) {
-		int new_width = need_width_realign ? width + (4 - (width % 4)) : width;
-		int new_height = need_height_realign ? height + (4 - (height % 4)) : height;
-
-		print_verbose(vformat("Compressed image's dimensions are not multiples of 4 (%dx%d), aligning to (%dx%d)", width, height, new_width, new_height));
-
-		width = new_width;
-		height = new_height;
-	}
-
 	Image::Format source_format = p_image->get_format();
 	Image::Format target_format = Image::FORMAT_MAX;
 
@@ -237,8 +286,8 @@ void image_decompress_bcdec(Image *p_image) {
 	// Decompress mipmaps.
 	for (int i = 0; i <= mm_count; i++) {
 		int mipmap_w = 0, mipmap_h = 0;
-		int64_t src_ofs = Image::get_image_mipmap_offset_and_dimensions(width, height, source_format, i, mipmap_w, mipmap_h);
-		int64_t dst_ofs = Image::get_image_mipmap_offset(width, height, target_format, i);
+		int64_t src_ofs = Image::get_image_mipmap_offset(width, height, source_format, i);
+		int64_t dst_ofs = Image::get_image_mipmap_offset_and_dimensions(width, height, target_format, i, mipmap_w, mipmap_h);
 		decompress_image(bcdec_format, rb + src_ofs, wb + dst_ofs, mipmap_w, mipmap_h);
 	}