Asset paths that begin with "/" don't work on Android

[shadowislord]

Due to the changes in jME 3.1 to use Android's AssetManager instead of the ClasspathLocator, paths that begin with a forward slash no longer work.

[zzuegg]

Rather strange, there is already some code in the AndroidLocator to remove a leading /

[nordfalk]

OK, I have used several days on this one!

Here is what extensive debugging finally brought to me.
As you can see from https://github.com/jMonkeyEngine/jmonkeyengine/blob/master/jme3-android/src/main/resources/com/jme3/asset/Android.cfg the com.jme3.asset.plugins.AndroidLocator gets as / as path:

# Android specific locators
LOCATOR / com.jme3.asset.plugins.AndroidLocator

This means that the locator gets rootPath = "/" .... and now look at

jmonkeyengine/jme3-android/src/main/java/com/jme3/asset/plugins/AndroidLocator.java

Line 26 in 445f7ed

public AssetInfo locate(AssetManager manager, AssetKey key) {

, in the case where the AssetKey starts with a "/" (like "/Textures/...")

String assetPath = rootPath + key.getName(); // will start with TWO slashes, like "//Textures/...

The // Fix path issues will remove ONE of the slashes, but not the other, which will make the system look in the root of the Linux Android file system :-(

Proposed fix 1: Avoid / as path

# Android specific locators
LOCATOR . com.jme3.asset.plugins.AndroidLocator

(best would be to set rootPath = "" but that isnt possible as it would not be valid syntax)

Proposed fix 2: ... or change to a while loop instead of an if statement:

  // Fix path issues
        while (assetPath.startsWith("/")) {
            // Remove leading /
            assetPath = assetPath.substring(1);
        }

Proposed fix 3: replace "//" with "/" before removing heading slash

        assetPath = assetPath.replace("//", "/");
        if (assetPath.startsWith("/")) {
            // Remove leading /
            assetPath = assetPath.substring(1);
        }

This bug affects all people that uses the SDK terrain editor (jMonkeyEngine 3.1-beta1-b002-SNAPSHOT) as it wrongly puths forward slashes in the paths of the textures in the .j3o file.

See also discussions

• https://hub.jmonkeyengine.org/t/solved-jme-3-1-android-terrain-texture-problems/34274/25 (contains a workaround where all textures are set manually)
• https://hub.jmonkeyengine.org/t/google-cardboard-support/31684/33?u=jacobnordfalk (issue 3)

[nordfalk]

Until this is fixed in the source the easiest workaround for the wrong path in the AndroidLocator is probably to unregister the locator with the wrong path and register it again with an empty path before you load the scene

        assetManager.unregisterLocator("/", AndroidLocator.class);
        assetManager.registerLocator("",AndroidLocator.class);

        Spatial scene = assetManager.loadModel("Scenes/myScene.j3o");

[stephengold]

Closed by PR #1577.