Add `etcpak` library for faster ETC/ETC2/S3TC imports.

- `etc` module was renamed to `etcpak` and modified to use the new library.
- PKM importer is removed in the process, it's obsolete.
- Old library `etc2comp` is removed.
- S3TC compression no longer done via `squish` (but decompression still is).
- Slight modifications to etcpak sources for MinGW compatibility,
  to fix LLVM `-Wc++11-narrowing` errors, and to allow using vendored or
  system libpng.

Co-authored-by: Rémi Verschelde <rverschelde@gmail.com>

1 files changed, 170 insertions, 0 deletions

diff --git a/modules/etcpak/image_etcpak.cpp b/modules/etcpak/image_etcpak.cpp
new file mode 100644
index 0000000000..251d2cd7b0
--- /dev/null
+++ b/modules/etcpak/image_etcpak.cpp
@@ -0,0 +1,170 @@
+/*************************************************************************/
+/*  image_etcpak.cpp                                                     */
+/*************************************************************************/
+/*                       This file is part of:                           */
+/*                           GODOT ENGINE                                */
+/*                      https://godotengine.org                          */
+/*************************************************************************/
+/* Copyright (c) 2007-2021 Juan Linietsky, Ariel Manzur.                 */
+/* Copyright (c) 2014-2021 Godot Engine contributors (cf. AUTHORS.md).   */
+/*                                                                       */
+/* Permission is hereby granted, free of charge, to any person obtaining */
+/* a copy of this software and associated documentation files (the       */
+/* "Software"), to deal in the Software without restriction, including   */
+/* without limitation the rights to use, copy, modify, merge, publish,   */
+/* distribute, sublicense, and/or sell copies of the Software, and to    */
+/* permit persons to whom the Software is furnished to do so, subject to */
+/* the following conditions:                                             */
+/*                                                                       */
+/* The above copyright notice and this permission notice shall be        */
+/* included in all copies or substantial portions of the Software.       */
+/*                                                                       */
+/* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,       */
+/* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF    */
+/* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.*/
+/* IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY  */
+/* CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,  */
+/* TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE     */
+/* SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.                */
+/*************************************************************************/
+
+#include "image_etcpak.h"
+
+#include "core/os/copymem.h"
+#include "core/os/os.h"
+#include "core/string/print_string.h"
+
+#include "thirdparty/etcpak/ProcessDxtc.hpp"
+#include "thirdparty/etcpak/ProcessRGB.hpp"
+
+// thresholds for the early compression-mode decision scheme in QuickETC2
+// which can be changed by the option -e
+float ecmd_threshold[3] = { 0.03f, 0.09f, 0.38f };
+
+EtcpakType _determine_etc_type(Image::UsedChannels p_source) {
+	switch (p_source) {
+		case Image::USED_CHANNELS_L:
+			return EtcpakType::ETCPAK_TYPE_ETC1;
+		case Image::USED_CHANNELS_LA:
+			return EtcpakType::ETCPAK_TYPE_ETC2_ALPHA;
+		case Image::USED_CHANNELS_R:
+			return EtcpakType::ETCPAK_TYPE_ETC2;
+		case Image::USED_CHANNELS_RG:
+			return EtcpakType::ETCPAK_TYPE_ETC2_RA_AS_RG;
+		case Image::USED_CHANNELS_RGB:
+			return EtcpakType::ETCPAK_TYPE_ETC2;
+		case Image::USED_CHANNELS_RGBA:
+			return EtcpakType::ETCPAK_TYPE_ETC2_ALPHA;
+		default:
+			return EtcpakType::ETCPAK_TYPE_ETC2_ALPHA;
+	}
+}
+
+EtcpakType _determine_dxt_type(Image::UsedChannels p_source) {
+	switch (p_source) {
+		case Image::USED_CHANNELS_L:
+			return EtcpakType::ETCPAK_TYPE_DXT1;
+		case Image::USED_CHANNELS_LA:
+			return EtcpakType::ETCPAK_TYPE_DXT5;
+		case Image::USED_CHANNELS_R:
+			return EtcpakType::ETCPAK_TYPE_DXT5;
+		case Image::USED_CHANNELS_RG:
+			return EtcpakType::ETCPAK_TYPE_DXT5_RA_AS_RG;
+		case Image::USED_CHANNELS_RGB:
+			return EtcpakType::ETCPAK_TYPE_DXT5;
+		case Image::USED_CHANNELS_RGBA:
+			return EtcpakType::ETCPAK_TYPE_DXT5;
+		default:
+			return EtcpakType::ETCPAK_TYPE_DXT5;
+	}
+}
+void _compress_etc2(Image *p_img, float p_lossy_quality, Image::UsedChannels p_source) {
+	EtcpakType type = _determine_etc_type(p_source);
+	_compress_etcpak(type, p_img, p_lossy_quality, false, p_source);
+}
+void _compress_bc(Image *p_img, float p_lossy_quality, Image::UsedChannels p_source) {
+	EtcpakType type = _determine_dxt_type(p_source);
+	_compress_etcpak(type, p_img, p_lossy_quality, false, p_source);
+}
+void _compress_etc1(Image *p_img, float p_lossy_quality) {
+	_compress_etcpak(EtcpakType::ETCPAK_TYPE_ETC1, p_img, p_lossy_quality, true, Image::USED_CHANNELS_RGB);
+}
+
+void _compress_etcpak(EtcpakType p_compresstype, Image *p_img, float p_lossy_quality, bool force_etc1_format, Image::UsedChannels p_channels) {
+	uint64_t t = OS::get_singleton()->get_ticks_msec();
+	Image::Format img_format = p_img->get_format();
+
+	if (img_format >= Image::FORMAT_DXT1) {
+		return; //do not compress, already compressed
+	}
+
+	if (img_format > Image::FORMAT_RGBA8) {
+		// TODO: we should be able to handle FORMAT_RGBA4444 and FORMAT_RGBA5551 eventually
+		return;
+	}
+
+	Image::Format format = Image::FORMAT_RGBA8;
+	if (p_img->get_format() != Image::FORMAT_RGBA8) {
+		p_img->convert(Image::FORMAT_RGBA8);
+	}
+	if (p_compresstype == EtcpakType::ETCPAK_TYPE_ETC1 || force_etc1_format) {
+		format = Image::FORMAT_ETC;
+	} else if (p_compresstype == EtcpakType::ETCPAK_TYPE_ETC2) {
+		format = Image::FORMAT_ETC2_RGB8;
+	} else if (p_compresstype == EtcpakType::ETCPAK_TYPE_ETC2_RA_AS_RG) {
+		format = Image::FORMAT_ETC2_RA_AS_RG;
+		p_img->convert_rg_to_ra_rgba8();
+	} else if (p_compresstype == EtcpakType::ETCPAK_TYPE_ETC2_ALPHA) {
+		format = Image::FORMAT_ETC2_RGBA8;
+	} else if (p_compresstype == EtcpakType::ETCPAK_TYPE_DXT1) {
+		format = Image::FORMAT_DXT1;
+	} else if (p_compresstype == EtcpakType::ETCPAK_TYPE_DXT5_RA_AS_RG) {
+		format = Image::FORMAT_DXT5_RA_AS_RG;
+		p_img->convert_rg_to_ra_rgba8();
+	} else if (p_compresstype == EtcpakType::ETCPAK_TYPE_DXT5) {
+		format = Image::FORMAT_DXT5;
+	} else {
+		ERR_FAIL();
+	}
+
+	const bool mipmap = p_img->has_mipmaps();
+	print_verbose("Encoding format: " + Image::get_format_name(format));
+
+	Ref<Image> new_img;
+	new_img.instance();
+	new_img->create(p_img->get_width(), p_img->get_height(), mipmap, format);
+	Vector<uint8_t> data = new_img->get_data();
+	uint8_t *wr = data.ptrw();
+
+	Ref<Image> image = p_img->duplicate();
+	int mmc = 1 + (mipmap ? Image::get_image_required_mipmaps(new_img->get_width(), new_img->get_height(), format) : 0);
+	for (int i = 0; i < mmc; i++) {
+		int ofs, size, mip_w, mip_h;
+		new_img->get_mipmap_offset_size_and_dimensions(i, ofs, size, mip_w, mip_h);
+		mip_w = (mip_w + 3) & ~3;
+		mip_h = (mip_h + 3) & ~3;
+		Vector<uint8_t> dst_data;
+		dst_data.resize(size);
+		int mipmap_ofs = image->get_mipmap_offset(i);
+
+		const uint32_t *image_read = (const uint32_t *)&image->get_data().ptr()[mipmap_ofs];
+		uint64_t *dst_write = (uint64_t *)dst_data.ptrw();
+		if (p_compresstype == EtcpakType::ETCPAK_TYPE_ETC1 || force_etc1_format) {
+			CompressEtc1RgbDither(image_read, dst_write, mip_w * mip_h / 16, mip_w);
+		} else if (p_compresstype == EtcpakType::ETCPAK_TYPE_ETC2 || p_compresstype == EtcpakType::ETCPAK_TYPE_ETC2_RA_AS_RG) {
+			CompressEtc2Rgb(image_read, dst_write, mip_w * mip_h / 16, mip_w);
+		} else if (p_compresstype == EtcpakType::ETCPAK_TYPE_ETC2_ALPHA) {
+			CompressEtc2Rgba(image_read, dst_write, mip_w * mip_h / 16, mip_w);
+		} else if (p_compresstype == EtcpakType::ETCPAK_TYPE_DXT5 || p_compresstype == EtcpakType::ETCPAK_TYPE_DXT5_RA_AS_RG) {
+			CompressDxt5(image_read, dst_write, mip_w * mip_h / 16, mip_w);
+		} else if (p_compresstype == EtcpakType::ETCPAK_TYPE_DXT1) {
+			CompressDxt1Dither(image_read, dst_write, mip_w * mip_h / 16, mip_w);
+		} else {
+			ERR_FAIL();
+		}
+		copymem(&wr[ofs], dst_data.ptr(), size);
+	}
+	p_img->create(new_img->get_width(), new_img->get_height(), mipmap, format, data);
+
+	print_verbose(vformat("ETCPAK encode took %s ms.", rtos(OS::get_singleton()->get_ticks_msec() - t)));
+}