Fix bug #2277 - GltfLoader

[JNightRider]

This PR fixes bug #2277 (GltfLoader issues).

This error originates when comparing 2 objects, the return is always false (result). jme3-plugins-json-gson always returns a new object of type com.jme3.plugins.json.JsonElement* (when accessing JSON elements), each new object confuses the gltf loader when compared using the equals(java.lang.Object) method.

A clear example where this error occurs is on line 1054 when searching for a JSON object within a list using the indexOf() method (class - GltfLoader).

Using the code created by @stephengold, now numComposers is 1

import com.jme3.anim.AnimComposer;
import com.jme3.app.SimpleApplication;
import com.jme3.scene.Node;
import com.jme3.scene.Spatial;
import com.jme3.scene.control.Control;
import com.jme3.scene.plugins.gltf.GltfModelKey;
import java.util.List;

public class TestYBot extends SimpleApplication {

    public static void main(String[] args) {
        TestYBot app = new TestYBot();
        app.start();
    }

    @Override
    public void simpleInitApp() {
        GltfModelKey modelKey = new GltfModelKey("YBot.gltf");
        Spatial modelRoot = assetManager.loadModel(modelKey);
        int numComposers = countControls(modelRoot, AnimComposer.class);
        System.out.println("numComposers = " + numComposers);
        stop();
    }

    /**
     * Count all controls of the specified type in the specified subtree of a
     * scene graph. Note: recursive!
     *
     * @param <T> subclass of Control
     * @param subtree the subtree to analyze (may be null, unaffected)
     * @param controlType the subclass of Control to search for
     * @return the count (&ge;0)
     */
    private static <T extends Control> int countControls(
            Spatial subtree, Class<T> controlType) {
        int result = 0;

        if (subtree != null) {
            int numControls = subtree.getNumControls();
            for (int controlI = 0; controlI < numControls; ++controlI) {
                Control control = subtree.getControl(controlI);
                if (controlType.isAssignableFrom(control.getClass())) {
                    ++result;
                }
            }
        }

        if (subtree instanceof Node) {
            Node node = (Node) subtree;
            List<Spatial> children = node.getChildren();
            for (Spatial child : children) {
                result += countControls(child, controlType);
            }
        }

        return result;
    }
}

[stephengold]

Thank you @JNightRider for investigating the issue and proposing a fix.

[pspeed42]

I don't understand why all of these import and library changes were necessary.

Edit: or rather, I don't understand how Ric's changes were working at all before without this.... and if it was working, I don't know why suddenly it needs to change just to fix how .equals()/.hashCode() is working. I'm very confused.

[stephengold]

@pspeed42 I disabled most of Riccardo's changes to work around the bug.

[JNightRider]

or rather, I don't understand how Ric's changes were working at all before without this.... and if it was working

These changes were removed as a temporary fix; Currently modules jme3-plugins-json and jme3-plugins-json-gson are not used.

I don't know why suddenly it needs to change just to fix how .equals()/.hashCode() is working.

@riccardobl's changes are no longer present in the loader (for the moment), it wouldn't make sense to fix something that isn't being used, which is why library imports (reconnect) are important.

[JNightRider]

With this 'commit', the changes have already been applied.

[stephengold]

Thanks for the comments and review.
@pspeed42 have all your concerns been addressed?

[pspeed42]

Yeah, I think so. Mostly I was confused. :)