iOS: Fix multiple issues with PVRTC import, disable ETC1

Fixes: #28683, #28621, #28596 and maybe others

For iOS we enable pvrtc feature by default for all backends
Etc1 for iOS doesn't have any sense, so it disabled.
Fixed checks in export editor.
Fixed pvrtc encoding procedure.

Edit by Akien: Forward-ported from #38076, this may not make sense as is for
Godot 4.0, but it's important that we have the latest code in sync with 3.2
for when more rendering backends and proper iOS support are added back.

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

4 files changed, 23 insertions, 7 deletions

diff --git a/editor/editor_export.cpp b/editor/editor_export.cpp
index 1d7429eb64..d3a4dbb6e7 100644
--- a/editor/editor_export.cpp
+++ b/editor/editor_export.cpp
@@ -1406,6 +1406,20 @@ String EditorExportPlatform::test_etc2() const {
 	return String();
 }
 
+String EditorExportPlatform::test_etc2_or_pvrtc() const {
+	String driver = ProjectSettings::get_singleton()->get("rendering/quality/driver/driver_name");
+	bool etc2_supported = ProjectSettings::get_singleton()->get("rendering/vram_compression/import_etc2");
+	bool pvrtc_supported = ProjectSettings::get_singleton()->get("rendering/vram_compression/import_pvrtc");
+
+	if (driver == "GLES2" && !pvrtc_supported) {
+		return TTR("Target platform requires 'PVRTC' texture compression for GLES2. Enable 'Import Pvrtc' in Project Settings.");
+	} else if (driver == "Vulkan" && !etc2_supported && !pvrtc_supported) {
+		// FIXME: Review if this is true for Vulkan.
+		return TTR("Target platform requires 'ETC2' or 'PVRTC' texture compression for Vulkan. Enable 'Import Etc 2' or 'Import Pvrtc' in Project Settings.");
+	}
+	return String();
+}
+
 int EditorExport::get_export_preset_count() const {
 	return export_presets.size();
 }
diff --git a/editor/editor_export.h b/editor/editor_export.h
index ac1051571c..fa6be88302 100644
--- a/editor/editor_export.h
+++ b/editor/editor_export.h
@@ -277,6 +277,7 @@ public:
 	virtual Ref<Texture2D> get_run_icon() const { return get_logo(); }
 
 	String test_etc2() const; //generic test for etc2 since most platforms use it
+	String test_etc2_or_pvrtc() const; // test for etc2 or pvrtc support for iOS
 	virtual bool can_export(const Ref<EditorExportPreset> &p_preset, String &r_error, bool &r_missing_templates) const = 0;
 
 	virtual List<String> get_binary_extensions(const Ref<EditorExportPreset> &p_preset) const = 0;
diff --git a/modules/pvr/texture_loader_pvr.cpp b/modules/pvr/texture_loader_pvr.cpp
index 36c0913f62..050dce1aab 100644
--- a/modules/pvr/texture_loader_pvr.cpp
+++ b/modules/pvr/texture_loader_pvr.cpp
@@ -213,10 +213,12 @@ static void _compress_pvrtc4(Image *p_img) {
 			int ofs, size, w, h;
 			img->get_mipmap_offset_size_and_dimensions(i, ofs, size, w, h);
 			Javelin::RgbaBitmap bm(w, h);
+			void *dst = (void *)bm.GetData();
+			copymem(dst, &r[ofs], size);
+			Javelin::ColorRgba<unsigned char> *dp = bm.GetData();
 			for (int j = 0; j < size / 4; j++) {
-				Javelin::ColorRgba<unsigned char> *dp = bm.GetData();
-				/* red and Green colors are swapped.  */
-				new (dp) Javelin::ColorRgba<unsigned char>(r[ofs + 4 * j + 2], r[ofs + 4 * j + 1], r[ofs + 4 * j], r[ofs + 4 * j + 3]);
+				/* red and blue colors are swapped.  */
+				SWAP(dp[j].r, dp[j].b);
 			}
 			new_img->get_mipmap_offset_size_and_dimensions(i, ofs, size, w, h);
 			Javelin::PvrTcEncoder::EncodeRgba4Bpp(&wr[ofs], bm);
diff --git a/platform/iphone/export/export.cpp b/platform/iphone/export/export.cpp
index 97f954ebb2..19f7c8e482 100644
--- a/platform/iphone/export/export.cpp
+++ b/platform/iphone/export/export.cpp
@@ -160,9 +160,8 @@ public:
 
 void EditorExportPlatformIOS::get_preset_features(const Ref<EditorExportPreset> &p_preset, List<String> *r_features) {
 	String driver = ProjectSettings::get_singleton()->get("rendering/quality/driver/driver_name");
-	if (driver == "GLES2") {
-		r_features->push_back("etc");
-	} else if (driver == "Vulkan") {
+	r_features->push_back("pvrtc");
+	if (driver == "Vulkan") {
 		// FIXME: Review if this is correct.
 		r_features->push_back("etc2");
 	}
@@ -1649,7 +1648,7 @@ bool EditorExportPlatformIOS::can_export(const Ref<EditorExportPreset> &p_preset
 		}
 	}
 
-	String etc_error = test_etc2();
+	String etc_error = test_etc2_or_pvrtc();
 	if (etc_error != String()) {
 		valid = false;
 		err += etc_error;