NullPointer on Geometry.setMorphState(String, float)

(Created with help from AI)

Geometry.setMorphState(String, float) throws NPE on a geometry whose morph state was never set

Summary

Geometry allocates its morphState array lazily. setMorphState(float[]) and
getMorphState() both allocate it on demand, but the two name-based overloads
setMorphState(String, float) and getMorphState(String) index the field
directly. Calling either of them before one of the array-based methods throws:

java.lang.NullPointerException: Cannot store to float array because "this.morphState" is null
        at com.jme3.scene.Geometry.setMorphState(Geometry.java:632)

Version

Reproduced on 3.8.1-stable, 3.9.0-stable and 3.10.0-beta1 (the newest
release on Maven Central), and the code is unchanged on current master
(65e413232).

Reproducer

No Application or render loop needed this is pure scene-graph state:

import com.jme3.scene.Geometry;
import com.jme3.scene.Mesh;
import com.jme3.scene.mesh.MorphTarget;

public class Repro {
    public static void main(String[] args) {
        Mesh mesh = new Mesh();
        mesh.addMorphTarget(new MorphTarget("morph"));
        Geometry geometry = new Geometry("body", mesh);

        System.out.println("morph index = " + mesh.getMorphIndex("morph")); // 0
        geometry.setMorphState("morph", 1f);                                // NPE
    }
}

getMorphState(String) fails the same way, at return morphState[index];.

Cause

In jme3-core/src/main/java/com/jme3/scene/Geometry.java, the array-based setter
allocates:

public void setMorphState(float[] state) {
    if (mesh == null || mesh.getMorphTargets().length == 0) {
        return;
    }
    int nbMorphTargets = mesh.getMorphTargets().length;
    if (morphState == null) {
        morphState = new float[nbMorphTargets];   // <-- allocated here
    }
    System.arraycopy(state, 0, morphState, 0, morphState.length);
    this.dirtyMorph = true;
}

…while the name-based one immediately below it does not:

public void setMorphState(String morphTarget, float state) {
    int index = mesh.getMorphIndex(morphTarget);
    if (index >= 0) {
        morphState[index] = state;   // <-- NPE if nothing allocated it yet
        this.dirtyMorph = true;
    }
}

getMorphState(String) has the same omission, even though the no-arg
getMorphState() right beside it allocates correctly.

Why it is easy to hit

Nothing else populates the array. MorphControl only ever reads it, and
GltfLoader attaches a MorphControl at all only when the asset carries an
animation channel targeting weights (its hasMorphTrack flag).

So an application that drives morph targets from its own code — expression
blending, a UI slider, any procedural deformation — has an unallocated array
exactly when it reaches for the name-based setter. And the name-based setter is
the natural choice there, because it is the only API that resolves a morph by
name; the float[] overload requires the caller to know target indices.

Working around it means calling setMorphState(new float[mesh.getMorphTargets().length])
once purely to force the allocation, which is not discoverable from the signature
or the javadoc.

Suggested fix

Route both name-based overloads through getMorphState(), which already
allocates on demand. The lookup guard is untouched, so an unknown name still
writes nothing and reads -1:

public void setMorphState(String morphTarget, float state) {
    int index = mesh.getMorphIndex(morphTarget);
    if (index >= 0) {
        getMorphState()[index] = state;
        this.dirtyMorph = true;
    }
}

public float getMorphState(String morphTarget) {
    int index = mesh.getMorphIndex(morphTarget);
    if (index < 0) {
        return -1;
    } else {
        return getMorphState()[index];
    }
}

A PR follows with this change plus GeometryMorphStateTest, covering the setter,
the getter, and the unknown-name path. The tests fail on master and pass with
the fix.

Start in jme3-core/src/main/java/com/jme3/scene/Geometry.java and inspect the name-based morph-state accessors alongside the array-based methods. Run GeometryMorphStateTest, which covers the setter, getter, and unknown-name path. Done means name-based access works before array initialization, unknown names retain their existing behavior, and the tests pass.