glTF + Physics + Babylon

Demos and projects
1

What is this?

I’d like to share a little project I’ve been working on lately with the Babylon community. It’s a Babylon plugin for loading glTF files with embedded physics information, making it possible to load up a glTF file and get simulation working without any code. It’s very much a beta, but I’ve been using it for months without [too many] problems.

I’ve got a demo app running with some sample assets on GitHub: linky

The plugin is available on NPM here and contains info on how to start using it in your project. Once the extension is loaded, you can load glTF+physics files as normal and stuff will start moving! Bug reports are welcome (bug fixes are even more welcome!)

Not only is there a Babylon plugin to load the physics, there’s also a Blender exporter, allowing physics properties to be configured in Blender and loaded straight into Babylon.

Little bit of extra background
There’s actually two glTF extensions added in the NPM package; one called “MSFT_rigid_bodies” and one called “KHR_rigid_bodies” - they both do pretty much the same thing at the moment. On the Havok team, we made the MSFT_rigid_bodies version a few years ago, while the KHR_rigid_bodies version is a version we (along with several others) want to get officially supported in glTF, so it’s in active development. I can promise we won’t make breaking changes to MSFT_rigid_bodies, but might do so for KHR_rigid_bodies.If you want a stable experience, I’d suggest using the “MSFT” version, while, if you want the bleeding edge, “KHR” is the way to go.

Sounds great! How do I get started?

Easy. Install the plugin:

npm install babylon-gltf-rigid-body-loader

And register it with Babylon:

import { GLTF2 } from "@babylonjs/loaders";
import { MSFT_RigidBodies_Plugin } from "babylon-gltf-rigid-body-loader";

GLTF2.GLTFLoader.RegisterExtension(
   "MSFT_rigid_bodies", function (loader) {
       return new MSFT_RigidBodies_Plugin(loader);
   });

That’s it! Then just load your glTF files!

You want to use Blender to export physics data? Also easy!

Download and unzip the Blender addon, then, in Blender, add the MSFT_rigid_bodies_file.py in the Addons settings. The README has some more info and pictures. This will get you the stable “MSFT” plugin version; if you want the latest-and-greatest, head on over to the main branch and get started (bug reports and bug fixes also welcome!)

10 Likes
2

Been stalking ur repo for those months :slight_smile:

cc @Lun
Rigid body go boin boin
.GitHub - Pauan/blender-rigid-body-bones: Blender Addon which adds rigid body / spring physics to bones

2 Likes
3

Video gif. A black dog stares wide-eyed as if in surprised shock.

It is happening !!!

1 Like
4

Boin boin!

1 Like
5

This now works in the playground as well. You will need to load the script and register the extensions until it’s finalized :slight_smile:

1 Like
6

Blender: 3.6
Addon: 0.0.2

Addon causes console error in headless (even though there is no physics in the scene). I did not export a GLTF file! The error does not seem to halt the script though.

//cmd call
call Blender.exe someBlendFile.blend --background --python somePythonScript.py

#python script that Blender runs in headless
import bpy
import sys
bpy.ops.wm.save_as_mainfile(filepath=bpy.data.filepath)

// Error msg

...>node ./opForeachFileRunStaticScript/index.js "cliAdHoc.py .\+Out\GameHiPoly\"
Processing Orc_M_HiPoly__f373.blend 1 / 23
Traceback (most recent call last):
  File "\Blender Foundation\Blender 3.6.0\3.6\scripts\modules\addon_utils.py", line 333, in enable
    mod = __import__(module_name)
  File "C:\Users\AppData\Roaming\Blender Foundation\Blender\3.6\scripts\addons\KHR_rigid_bodies.py", line 702, in <module>
    viewportRenderHelper = KHRPhysicsSettingsViewportRenderHelper()
  File "C:\Users\AppData\Roaming\Blender Foundation\Blender\3.6\scripts\addons\KHR_rigid_bodies.py", line 541, in __init__
    self.shader = gpu.shader.from_builtin('3D_UNIFORM_COLOR')

SystemError: GPU API is not available in background mode
´´´
7

Ok, I see. It is just the KHRPhysicsSettingsViewportRenderHelper. If you go to here https://github.com/eoineoineoin/glTF_Physics_Blender_Exporter/blob/15d9f5a7259e394c0f8b6697917a2ee54ce93d15/addons/KHR_rigid_bodies.py#L541 and comment this line, there is no error in headless.

Would it suffice to add a check for headless and if so, just do not assign “self.shader”?