Merge pull request #69448 from BastiaanOlij/fix_etc_rgba_bgra_issue

ETCPAK expects BGRA data for ETC

core/io/image.cpp

@@ -3798,6 +3798,19 @@ void Image::convert_ra_rgba8_to_rg() {
 	}
 }
 
+void Image::convert_rgba8_to_bgra8() {
+	ERR_FAIL_COND(format != FORMAT_RGBA8);
+	ERR_FAIL_COND(!data.size());
+
+	int s = data.size();
+	uint8_t *w = data.ptrw();
+	for (int i = 0; i < s; i += 4) {
+		uint8_t r = w[i];
+		w[i] = w[i + 2]; // Swap R to B
+		w[i + 2] = r; // Swap B to R
+	}
+}
+
 Error Image::_load_from_buffer(const Vector<uint8_t> &p_array, ImageMemLoadFunc p_loader) {
 	int buffer_size = p_array.size();
 

core/io/image.h

@@ -391,6 +391,7 @@ public:
 
 	void convert_rg_to_ra_rgba8();
 	void convert_ra_rgba8_to_rg();
+	void convert_rgba8_to_bgra8();
 
 	Image(const uint8_t *p_mem_png_jpg, int p_len = -1);
 	Image(const char **p_xpm);

modules/etcpak/image_compress_etcpak.cpp

@@ -111,13 +111,16 @@ void _compress_etcpak(EtcpakType p_compresstype, Image *r_img, float p_lossy_qua
 	Image::Format target_format = Image::FORMAT_RGBA8;
 	if (p_compresstype == EtcpakType::ETCPAK_TYPE_ETC1) {
 		target_format = Image::FORMAT_ETC;
+		r_img->convert_rgba8_to_bgra8(); // It's badly documented but ETCPAK seems to be expected BGRA8 for ETC.
 	} else if (p_compresstype == EtcpakType::ETCPAK_TYPE_ETC2) {
 		target_format = Image::FORMAT_ETC2_RGB8;
+		r_img->convert_rgba8_to_bgra8(); // It's badly documented but ETCPAK seems to be expected BGRA8 for ETC.
 	} else if (p_compresstype == EtcpakType::ETCPAK_TYPE_ETC2_RA_AS_RG) {
 		target_format = Image::FORMAT_ETC2_RA_AS_RG;
 		r_img->convert_rg_to_ra_rgba8();
 	} else if (p_compresstype == EtcpakType::ETCPAK_TYPE_ETC2_ALPHA) {
 		target_format = Image::FORMAT_ETC2_RGBA8;
+		r_img->convert_rgba8_to_bgra8(); // It's badly documented but ETCPAK seems to be expected BGRA8 for ETC.
 	} else if (p_compresstype == EtcpakType::ETCPAK_TYPE_DXT1) {
 		target_format = Image::FORMAT_DXT1;
 	} else if (p_compresstype == EtcpakType::ETCPAK_TYPE_DXT5_RA_AS_RG) {