[PicoXR] Use compressed ETC2 textures for environments

PicoOS v5.4 added support for ETC2 compressed textures. We removed
support for PicoOS < v5.7 when the version check was added. This means
that we can now finally switch to using compressed textures also
for Pico devices.

There is no need to distribute the PNG versions in the Pico package.
That would save us 14MB in the distributed APK. Apart from that
the external environments code was also modified to download the
KTX versions of the textures.

The already downloaded environments will be used though because
we have the same id for the different formats of the same environment.
But for the builtin ones, and new downloads the KTX versions
would be the selected choice.

Fixes #522

app/src/common/shared/com/igalia/wolvic/utils/EnvironmentUtils.java

@@ -20,7 +20,7 @@ public class EnvironmentUtils {
 
     public static final String ENVS_FOLDER = "envs";
     public static final String BUILTIN_ENVS_PREFIX = "cubemap/";
-    public static String[] SUPPORTED_ENV_EXTENSIONS = (DeviceType.isPicoXR() || DeviceType.isOculusBuild()) ?
+    public static String[] SUPPORTED_ENV_EXTENSIONS = (DeviceType.isOculusBuild()) ?
             new String[]{".jpg", ".png"} : new String[]{".ktx", ".jpg", ".png"};
 
     /**
@@ -209,10 +209,10 @@ public static Environment getExternalEnvironmentById(@NonNull Context context, @
      */
     @Nullable
     public static String getEnvironmentPayload(Environment env) {
-        // Pico4x and Meta Quest (after v69) do not support compressed textures for the cubemap.
         if (DeviceType.isPicoXR() || DeviceType.isOculusBuild()) {
             String payload = env.getPayload();
-            String format = "_misc";
+            // Meta Quest (after v69) do not support compressed textures for the cubemap.
+            String format = DeviceType.isOculusBuild() ? "_misc" : "_ktx";
             int at = payload.lastIndexOf(".");
             return payload.substring(0, at) + format + "_srgb" + payload.substring(at);
         }

app/src/main/cpp/BrowserWorld.cpp

@@ -2028,19 +2028,24 @@ BrowserWorld::CreateSkyBox(const std::string& aBasePath, const std::string& aExt
     }
     return;
   }
-#if PICOXR
-  // Pico's OpenXR runtime does not support compressed textures at the moment. Use PNGs in the
-  // meantime.
-  const std::string extension = aExtension.empty() ? ".png" : aExtension;
-  GLenum glFormat = GL_SRGB8_ALPHA8;
-#elif OCULUSVR
+#if defined(OCULUSVR) || defined(PICOXR)
+  bool usesSRGB = true;
+#else
+  bool usesSRGB = false;
+#endif
+
+#if OCULUSVR
   // Meta Quest (after v69) does not support compressed textures for the cubemap.
   const std::string extension = aExtension.empty() ? ".png" : aExtension;
-  GLenum glFormat = GL_SRGB8_ALPHA8;
 #else
   const std::string extension = aExtension.empty() ? ".ktx" : aExtension;
-  GLenum glFormat = extension == ".ktx" ? GL_COMPRESSED_RGB8_ETC2 : GL_RGBA8;
 #endif
+  GLenum glFormat;
+  if (usesSRGB)
+    glFormat = extension == ".ktx" ? GL_COMPRESSED_SRGB8_ETC2 : GL_SRGB8_ALPHA8;
+  else
+    glFormat = extension == ".ktx" ? GL_COMPRESSED_RGB8_ETC2 : GL_RGBA8;
+
   const int32_t size = 1024;
   if (m.skybox) {
     m.skybox->SetVisible(true);