godot/modules/squish/image_decompress_squish.cpp

/**************************************************************************/
/*  image_decompress_squish.cpp                                           */
/**************************************************************************/
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/* Copyright (c) 2014-present Godot Engine contributors (see AUTHORS.md). */
/* Copyright (c) 2007-2014 Juan Linietsky, Ariel Manzur.                  */
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#include "image_decompress_squish.h"

#include <squish.h>

void image_decompress_squish(Image *p_image) {
	int w = p_image->get_width();
	int h = p_image->get_height();

	Image::Format source_format = p_image->get_format();
	Image::Format target_format = Image::FORMAT_RGBA8;

	Vector<uint8_t> data;
	int64_t target_size = Image::get_image_data_size(w, h, target_format, p_image->has_mipmaps());
	int mm_count = p_image->get_mipmap_count();
	data.resize(target_size);

	const uint8_t *rb = p_image->get_data().ptr();
	uint8_t *wb = data.ptrw();

	int squish_flags = 0;

	switch (source_format) {
		case Image::FORMAT_DXT1:
			squish_flags = squish::kDxt1;
			break;

		case Image::FORMAT_DXT3:
			squish_flags = squish::kDxt3;
			break;

		case Image::FORMAT_DXT5:
		case Image::FORMAT_DXT5_RA_AS_RG:
			squish_flags = squish::kDxt5;
			break;

		case Image::FORMAT_RGTC_R:
			squish_flags = squish::kBc4;
			break;

		case Image::FORMAT_RGTC_RG:
			squish_flags = squish::kBc5;
			break;

		default:
			ERR_FAIL_MSG("Squish: Can't decompress unknown format: " + itos(p_image->get_format()) + ".");
			break;
	}

	for (int i = 0; i <= mm_count; i++) {
		int64_t src_ofs = 0, mipmap_size = 0;
		int mipmap_w = 0, mipmap_h = 0;
		p_image->get_mipmap_offset_size_and_dimensions(i, src_ofs, mipmap_size, mipmap_w, mipmap_h);

		int64_t dst_ofs = Image::get_image_mipmap_offset(p_image->get_width(), p_image->get_height(), target_format, i);
		squish::DecompressImage(&wb[dst_ofs], w, h, &rb[src_ofs], squish_flags);

		w >>= 1;
		h >>= 1;
	}

	p_image->set_data(p_image->get_width(), p_image->get_height(), p_image->has_mipmaps(), target_format, data);

	if (source_format == Image::FORMAT_DXT5_RA_AS_RG) {
		p_image->convert_ra_rgba8_to_rg();
	}
}