getting basic example working on glitch

[kfarr]

Hi Diarmid, not urgent but I was trying to get a basic example working but was not successful. Here is the sample project, all it is doing is loading a street and then trying to load 1 instance of an instanced mesh. Is there anything obviously wrong with my setup here or is this a bigger issue related to #28 ?

https://glitch.com/edit/#!/3dstreet-simple-instanced-mesh

[diarmidmackenzie]

Hi Kieran, I took a look at the glitch and I'm not sure I understand what the problem is?

The multiple instances of the car seem to be rendering OK to me. Can you explain what the issue is?

I'll post some updates on #28 with latest status there.

[kfarr]

Hey @diarmidmackenzie sorry for the utterly confusing glitch. I've updated it to (a) remove the confusing street scene and (b) to show 4 examples clearly commented:

      <!-- normal gltf loader using asset loader -->
      <a-entity position="1 0 -5" gltf-model="#car-model"></a-entity>

      <!-- instanced mesh using asset loader -->
      <a-entity id="car-instanced" gltf-model="#car-model" instanced-mesh="capacity: 1000; positioning: world; updateMode: auto"></a-entity>
      <a-entity position="-1 0 -10" instanced-mesh-member="mesh:#car-instanced"></a-entity>

      <!-- using 3dstreet mixin (which uses gltf-model="url(path)" scheme) -->
      <a-entity position="-1 0 -5" mixin="sedan-rig"></a-entity>

      <!-- instanced mesh using 3dstreet mixin -->
      <a-entity id="car-instanced-mixin" mixin="sedan-rig" instanced-mesh="capacity: 1000; positioning: world; updateMode: auto"></a-entity>
      <a-entity position="1 0 -10" instanced-mesh-member="mesh:#car-instanced-mixin"></a-entity>

The "normal" loading ones are closest to the camera at -5 z and the instanced ones are at -10 z but neither appears to load.

Why am I bothering you about this? We are finally getting close to creating scenes to "show off" 3dstreet like this one: https://little-slow-november.glitch.me/ and we plan to have many vehicles and buildings that would definitely benefit from this component. That said there are a lot of irons in the fire right now so this is not urgent and I don't want to distract from higher priority things you might be working on.

[diarmidmackenzie]

OK - this issue is that the model uses a SkinnedMesh, which isn't working.

The issue is with the code that traverses the GLTF model searching for the Meshes that make up the model.

instanced-mesh/src/instanced-mesh.js

Line 352 in 3c1ce5f

if(node.type != "Mesh") return;

It identifies object3Ds of type 'Mesh', but not of type 'SkinnedMesh'.

There's no support in Three.js for instancing of skinned meshes....

https://discourse.threejs.org/t/instancedmesh-animations-like-with-skinnedmesh/12388/7#:~:text=No%2C%20that%20is%20not%20yet%20possible.

....so I'm not sure this can be accommodated very easily.
Edit: here's the latest on Instanced Skinned Meshes in THREE.js. Maybe not a million miles away from happening...

However I can definitely do a better job of error handling in this case. For now, I'll do a quick PR to document the restricton & provide a helpful error message when using Skinned Meshes.

Do you have the option of moving your model away from a Skinned Mesh?

[diarmidmackenzie]

One approach that may be useful in some cases would be to bake the default skeleton position into a standard Mesh. This would lose the animation capabilities of the Skinned Mesh, but would at least render a static version of the Skinned Mesh correctly.

Not sure I want to encourage this, though - in most cases, it's going to be preferable to pre-bake the bone positions into the model, and create a new GLTF that contains a Mesh rather than a Skinned Mesh.

It would be nice to be able to recommend a tool that can do this, but I don't know of one.

[diarmidmackenzie]

It's possible this baking can be done in Blender using something like this:
https://blender.stackexchange.com/questions/22882/how-do-i-delete-an-armature-but-keep-the-baked-pose

[kfarr]

Thanks @diarmidmackenzie you're totally right and sorry for not thinking of this earlier. We will do this again with simplified models.

[kfarr]

closing for now since this is out of scope for this component