godot/modules/bcdec/image_decompress_bcdec.cpp

/**************************************************************************/
/*  image_decompress_bcdec.cpp                                            */
/**************************************************************************/
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/* Copyright (c) 2007-2014 Juan Linietsky, Ariel Manzur.                  */
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#include "image_decompress_bcdec.h"

#include "core/os/os.h"
#include "core/string/print_string.h"

#define BCDEC_IMPLEMENTATION
#include "thirdparty/misc/bcdec.h"

inline void bcdec_bc6h_half_s(const void *compressedBlock, void *decompressedBlock, int destinationPitch) {
	bcdec_bc6h_half(compressedBlock, decompressedBlock, destinationPitch, true);
}

inline void bcdec_bc6h_half_u(const void *compressedBlock, void *decompressedBlock, int destinationPitch) {
	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);

#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;                                         \
	}

#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); \
					}                                                                                                                                 \
				}                                                                                                                                     \
			}                                                                                                                                         \
		}                                                                                                                                             \
	}

	if (width % 4 != 0 || height % 4 != 0) {
		uint64_t src_pos = 0;

		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];

		switch (format) {
			case BCdec_BC1: {
				DECOMPRESS_LOOP_SAFE(bcdec_bc1, BCDEC_BC1_BLOCK_SIZE, 4, 4, rgba8_output)
			} break;
			case BCdec_BC2: {
				DECOMPRESS_LOOP_SAFE(bcdec_bc2, BCDEC_BC2_BLOCK_SIZE, 4, 4, rgba8_output)
			} break;
			case BCdec_BC3: {
				DECOMPRESS_LOOP_SAFE(bcdec_bc3, BCDEC_BC3_BLOCK_SIZE, 4, 4, rgba8_output)
			} break;
			case BCdec_BC4: {
				DECOMPRESS_LOOP_SAFE(bcdec_bc4, BCDEC_BC4_BLOCK_SIZE, 1, 1, r8_output)
			} break;
			case BCdec_BC5: {
				DECOMPRESS_LOOP_SAFE(bcdec_bc5, BCDEC_BC5_BLOCK_SIZE, 2, 2, rg8_output)
			} break;
			case BCdec_BC6U: {
				DECOMPRESS_LOOP_SAFE(bcdec_bc6h_half_u, BCDEC_BC6H_BLOCK_SIZE, 6, 3, rgbh_output)
			} break;
			case BCdec_BC6S: {
				DECOMPRESS_LOOP_SAFE(bcdec_bc6h_half_s, BCDEC_BC6H_BLOCK_SIZE, 6, 3, rgbh_output)
			} break;
			case BCdec_BC7: {
				DECOMPRESS_LOOP_SAFE(bcdec_bc7, BCDEC_BC7_BLOCK_SIZE, 4, 4, rgba8_output)
			} break;
		}

	} else {
		uint64_t src_pos = 0, dst_pos = 0;

		switch (format) {
			case BCdec_BC1: {
				DECOMPRESS_LOOP(bcdec_bc1, BCDEC_BC1_BLOCK_SIZE, 4, 4)
			} break;
			case BCdec_BC2: {
				DECOMPRESS_LOOP(bcdec_bc2, BCDEC_BC2_BLOCK_SIZE, 4, 4)
			} break;
			case BCdec_BC3: {
				DECOMPRESS_LOOP(bcdec_bc3, BCDEC_BC3_BLOCK_SIZE, 4, 4)
			} break;
			case BCdec_BC4: {
				DECOMPRESS_LOOP(bcdec_bc4, BCDEC_BC4_BLOCK_SIZE, 1, 1)
			} break;
			case BCdec_BC5: {
				DECOMPRESS_LOOP(bcdec_bc5, BCDEC_BC5_BLOCK_SIZE, 2, 2)
			} break;
			case BCdec_BC6U: {
				DECOMPRESS_LOOP(bcdec_bc6h_half_u, BCDEC_BC6H_BLOCK_SIZE, 6, 3)
			} break;
			case BCdec_BC6S: {
				DECOMPRESS_LOOP(bcdec_bc6h_half_s, BCDEC_BC6H_BLOCK_SIZE, 6, 3)
			} break;
			case BCdec_BC7: {
				DECOMPRESS_LOOP(bcdec_bc7, BCDEC_BC7_BLOCK_SIZE, 4, 4)
			} break;
		}
	}

#undef DECOMPRESS_LOOP
#undef DECOMPRESS_LOOP_SAFE
}

void image_decompress_bcdec(Image *p_image) {
	uint64_t start_time = OS::get_singleton()->get_ticks_msec();

	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;

	BCdecFormat bcdec_format = BCdec_BC1;

	switch (source_format) {
		case Image::FORMAT_DXT1:
			bcdec_format = BCdec_BC1;
			target_format = Image::FORMAT_RGBA8;
			break;

		case Image::FORMAT_DXT3:
			bcdec_format = BCdec_BC2;
			target_format = Image::FORMAT_RGBA8;
			break;

		case Image::FORMAT_DXT5:
		case Image::FORMAT_DXT5_RA_AS_RG:
			bcdec_format = BCdec_BC3;
			target_format = Image::FORMAT_RGBA8;
			break;

		case Image::FORMAT_RGTC_R:
			bcdec_format = BCdec_BC4;
			target_format = Image::FORMAT_R8;
			break;

		case Image::FORMAT_RGTC_RG:
			bcdec_format = BCdec_BC5;
			target_format = Image::FORMAT_RG8;
			break;

		case Image::FORMAT_BPTC_RGBFU:
			bcdec_format = BCdec_BC6U;
			target_format = Image::FORMAT_RGBH;
			break;

		case Image::FORMAT_BPTC_RGBF:
			bcdec_format = BCdec_BC6S;
			target_format = Image::FORMAT_RGBH;
			break;

		case Image::FORMAT_BPTC_RGBA:
			bcdec_format = BCdec_BC7;
			target_format = Image::FORMAT_RGBA8;
			break;

		default:
			ERR_FAIL_MSG("bcdec: Can't decompress unknown format: " + Image::get_format_name(source_format) + ".");
			break;
	}

	int mm_count = p_image->get_mipmap_count();
	int64_t target_size = Image::get_image_data_size(width, height, target_format, p_image->has_mipmaps());

	// Decompressed data.
	Vector<uint8_t> data;
	data.resize(target_size);
	uint8_t *wb = data.ptrw();

	// Source data.
	const uint8_t *rb = p_image->get_data().ptr();

	// 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);
		decompress_image(bcdec_format, rb + src_ofs, wb + dst_ofs, mipmap_w, mipmap_h);
	}

	p_image->set_data(width, height, p_image->has_mipmaps(), target_format, data);

	// Swap channels if the format is using a channel swizzle.
	if (source_format == Image::FORMAT_DXT5_RA_AS_RG) {
		p_image->convert_ra_rgba8_to_rg();
	}

	print_verbose(vformat("bcdec: Decompression of a %dx%d %s image with %d mipmaps took %d ms.",
			p_image->get_width(), p_image->get_height(), Image::get_format_name(source_format), p_image->get_mipmap_count(), OS::get_singleton()->get_ticks_msec() - start_time));
}