How can I export a simple rigged model from Maya for use in Scenekit?

Question

I am attempting to experiment with Apple’s Fox game SceneKit example (link below) by adding a model with a simple animation like the ‘panda.scn’ and ‘walk.scn’ assets.

I can create a static model with no joints or animation that works: e.g. In Maya (2017) I add a simple sphere, export selection to FBX_DAE (COLLADA) file, drag it into the project in XCode and convert it to a SCN file. I can then drag that model into the ‘level.scn’, position and scale it as I’d expect.

However as soon as I add any animation or joints to my model I lose the ability to position and scale the model in XCode.

In Maya I add two joints to my sphere select the sphere and joints and export as above. When I examine the model SCN in XCode (either in isolation or as a reference within another scene) I find that I cannot apply any translation or scaling. XCode lets me move the xyz locators in the GUI and update scale but the model does not change. I can see the mesh and joints in the outline view and I have tried moving the joints instead of the mesh, but they do nothing. I have even tried ignoring the GUI and positioning the model in code just as the panda character is set up, but applying positions or transforms to the node does nothing - it always appears at the origin and default scale.

Ignoring that for the moment, my understanding from looking at the ‘walk.scn’ file is that an animation is just an export of the joints with keyframes. I have tried to reproduce that by exporting only the joints to a separate DAE and importing it, then applying that in code as they do with the ‘walkAnimation’. This seems to do nothing as well.

I have experimented with various settings of the FBX_DAE export dialog including baking animations (By the way - what is the difference between baking an animation on export vs baking it in Maya before export? The former seems to do something and the other does nothing in my tests.)

I would dearly love a workflow for creating some simple character animations in Maya and getting them into SceneKit. Any help is greatly appreciated.

For reference:

Apple’s source: https://developer.apple.com/library/content/samplecode/Fox/Introduction/Intro.html

Maya scene for my trivial ball model with two joints: http://pat.net/misc/ball1.mb and the DAE output from Maya for that: http://pat.net/misc/ball1.dae

UPDATE:

Mnuages's answer appears to be correct in that when I added a parent control over the geometry and joints SceneKit then allowed me to move them. But even after brushing up on my understanding of how these nodes and their transforms relate in Maya I do not feel that I have a real understanding of how SceneKit is interpreting them. (Would love to read some docs on that would illuminate this more if they exist).

UPDATE #2:

I was finally able to create an animation by doing the following: 1) Export either the full scene or just the joint with the animation being sure to select the "bake animation" option in the DAE export dialog or bake the entire animation using Key->Bake Animation. 2) It only works if I load the DAE file in scenekit instead of converting it to an SCN. Converting to SCN format seems to lose the animation.

Answer 1

what happens is that the node named joint1 is animated by the joint1-anim animation. So even if you move joint1 in the editor, what you see on screen is the result after the animation is evaluated.

If you create an intermediate node, say joint1-parent, and make joint1 as child node of joint1-parent, then you'll be able to translate and rotate joint1-parent freely and see the effects on joint1.

As for why moving pSphere does not change anything, it's the same idea. Just like the animation overrides the position, the skeleton will reposition the mesh.