software skinning shouldn't require vertex normals

[stephengold]

Trying to render a model imported from https://github.com/KhronosGroup/glTF-Sample-Models/tree/master/2.0/RecursiveSkeletons/glTF using MonkeyWrench:

Sep 30, 2023 11:58:32 AM com.jme3.app.LegacyApplication handleError
SEVERE: Uncaught exception thrown in Thread[jME3 Main,5,main]
java.lang.NullPointerException
	at com.jme3.anim.SkinningControl.resetToBind(SkinningControl.java:332)
	at com.jme3.anim.SkinningControl.controlRenderSoftware(SkinningControl.java:255)
	at com.jme3.anim.SkinningControl.controlRender(SkinningControl.java:304)
	at com.jme3.scene.control.AbstractControl.render(AbstractControl.java:126)
	at com.jme3.scene.Spatial.runControlRender(Spatial.java:763)
	at com.jme3.renderer.RenderManager.renderSubScene(RenderManager.java:796)
	at com.jme3.renderer.RenderManager.renderSubScene(RenderManager.java:806)
	at com.jme3.renderer.RenderManager.renderScene(RenderManager.java:780)
	at com.jme3.renderer.RenderManager.renderViewPort(RenderManager.java:1205)
	at com.jme3.renderer.RenderManager.render(RenderManager.java:1287)
	at com.jme3.app.SimpleApplication.update(SimpleApplication.java:278)
	at com.jme3.system.lwjgl.LwjglWindow.runLoop(LwjglWindow.java:628)
	at com.jme3.system.lwjgl.LwjglWindow.run(LwjglWindow.java:717)
	at java.base/java.lang.Thread.run(Thread.java:829)

One of the many quirks of the RecursiveSkeletons model is that its mesh doesn't include vertex normals. I believe SkinningControl should be able to handle that, just like it handles meshes without tangents. Looking at the code, it's clear this possibility wasn't considered:

jmonkeyengine/jme3-core/src/main/java/com/jme3/anim/SkinningControl.java

Lines 320 to 334 in 4de10c3

	Mesh mesh = geometry.getMesh();
	if (mesh != null && mesh.isAnimated()) {
	Buffer bwBuff = mesh.getBuffer(Type.BoneWeight).getData();
	Buffer biBuff = mesh.getBuffer(Type.BoneIndex).getData();
	if (!biBuff.hasArray() || !bwBuff.hasArray()) {
	mesh.prepareForAnim(true); // prepare for software animation
	}
	VertexBuffer bindPos = mesh.getBuffer(Type.BindPosePosition);
	VertexBuffer bindNorm = mesh.getBuffer(Type.BindPoseNormal);
	VertexBuffer pos = mesh.getBuffer(Type.Position);
	VertexBuffer norm = mesh.getBuffer(Type.Normal);
	FloatBuffer pb = (FloatBuffer) pos.getData();
	FloatBuffer nb = (FloatBuffer) norm.getData();
	FloatBuffer bpb = (FloatBuffer) bindPos.getData();
	FloatBuffer bnb = (FloatBuffer) bindNorm.getData();

In case you're wondering, the model doesn't include vertex tangents either.

[stephengold]

The old animation system has a similar issue:

jmonkeyengine/jme3-core/src/main/java/com/jme3/animation/SkeletonControl.java

Lines 466 to 467 in 4de10c3

	VertexBuffer nb = mesh.getBuffer(Type.Normal);
	FloatBuffer fnb = (FloatBuffer) nb.getData();