solve issue jMonkeyEngine#1939 [NPE in FbxMesh.applyCluster()] (jMonk…

…eyEngine#1940)

* FBXCluster:  create empty arrays if the cluster contains no keyframes

* FbxLoader:  don't construct an animation if there are no keyframes

jme3-plugins/src/fbx/java/com/jme3/scene/plugins/fbx/FbxLoader.java

@@ -343,6 +343,9 @@ private void constructAnimations() {
 
  // At this point we can construct the animation for all pairs ...
  for (FbxToJmeTrack pair : pairs.values()) {
+ if (pair.countKeyframes() == 0) {
+ continue;
+ }
  String animName = pair.animStack.getName();
  float duration = pair.animStack.getDuration();
 

jme3-plugins/src/fbx/java/com/jme3/scene/plugins/fbx/anim/FbxCluster.java

@@ -93,6 +93,12 @@ public void fromElement(FbxElement element) {
  }
  }
  }
+
+ if (indexes == null && weights == null) {
+ // The cluster doesn't contain any keyframes!
+ this.indexes = new int[0];
+ this.weights = new double[0];
+ }
  }
 
  public int[] getVertexIndices() {
@@ -129,4 +135,4 @@ public void connectObject(FbxObject object) {
  public void connectObjectProperty(FbxObject object, String property) {
  unsupportedConnectObjectProperty(object, property);
  }
-}
+}

jme3-plugins/src/fbx/java/com/jme3/scene/plugins/fbx/anim/FbxToJmeTrack.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2009-2021 jMonkeyEngine
+ * Copyright (c) 2009-2023 jMonkeyEngine
  * All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
@@ -91,7 +91,23 @@ public BoneTrack toJmeBoneTrack(int boneIndex, Transform inverseBindPose) {
  public SpatialTrack toJmeSpatialTrack() {
  return (SpatialTrack) toJmeTrackInternal(-1, null);
  }
-
+
+ /**
+ * Counts how many keyframes there are in the included curves.
+ *
+ * @return the total number of keyframes (≥0)
+ */
+ public int countKeyframes() {
+ int count = 0;
+ for (FbxAnimCurveNode curveNode : animCurves.values()) {
+ for (FbxAnimCurve curve : curveNode.getCurves()) {
+ count += curve.getKeyTimes().length;
+ }
+ }
+
+ return count;
+ }
+
  public float getDuration() {
  long[] keyframes = getKeyTimes();
  return (float) (keyframes[keyframes.length - 1] * FbxAnimUtil.SECONDS_PER_UNIT);