GltfLoader loses animation data

[stephengold]

Forum thread: https://hub.jmonkeyengine.org/t/incomplete-animation/45558

I've tracked this down to the TrackData.update() method. For the "character.gltf" model's "stand" animation, the track for node 4 ("all") has 3 translation keyframes prior to TrackData.update() but only 1 keyframe after the invocation.

timeArrays.get(0) is rotation data, for which there is a single keyframe at t=0.
timeArrays.get(1) is translation data, for which there are 3 keyframes: at t=0, t=2.25, and t=4.25.

Those last 2 keyframes never get merged into the keyFrames list, so translation data is lost.

[stephengold]

"TrackData.java" implements a merge sort using spaghetti code with poor encapsulation. But in case nobody feels like rewriting it from scratch, here is a straightforward patch that I believe will solve this issue:

--- a/jme3-plugins/src/gltf/java/com/jme3/scene/plugins/gltf/TrackData.java
+++ b/jme3-plugins/src/gltf/java/com/jme3/scene/plugins/gltf/TrackData.java
@@ -90,7 +90,14 @@
                         KeyFrame kf = keyFrames.get(j);
                         if (Float.floatToIntBits(kf.time) != Float.floatToIntBits(time)) {
                             if (time > kf.time) {
-                                continue;
+                                if (j < keyFrames.size() - 1) {
+                                    // Keep searching for the insertion point.
+                                    continue;
+                                }
+                                kf = new KeyFrame();
+                                kf.time = time;
+                                // Add kf after the last keyframe in the list.
+                                keyFrames.add(kf);
                             } else {
                                 kf = new KeyFrame();
                                 kf.time = time;