Rotating specific parts of an OBJ file?


I’m trying to build a pretty basic flight simulator. I’ve got a model of a plane that I built in Blender with different objects for parts of the plane: fuselage, wings, ailerons, elevators, etc. I exported it as a .obj file and I’m able to load and render the entire model using ObjLoader and a TriMesh.

I’m trying to figure out the best way to start modifying the mesh based on the inputs so that the control surfaces rotate in place as the plane maneuvers. A quick (though probably not the most efficient) idea is to export with objects as groups and then load each group into its own mesh and render them all individually. Then I can rotate each piece individually (though I’m not sure how I’ll figure out the proper origin for the rotations) before rendering it.

What’s a better way to do this?


Maybe it is worth to look into some model loading blocks like @ryanbartley’s new gitf or @num3ric’s Cinder-Skinning/ModelSource block or assimp. These are more complex than ObjLoader, but you can access the node graph, so rotating the mesh groups should be easier.


Oh very helpful. I’m going to do some investigation on the gltf block since that seems like a nice future proof direction.


GLTF makes sense to me too. FWIW at LucasArts we skinned airplanes, things like rudders and ailerons don’t get moved as individual meshes but as a verts bound to a joint.

There’s other advantages to skinning your plane as well; you can have the wings flex, so that they droop on the runway, and bend upwards in flight, just as real wings do. In a combat sim you can also model damage with skinning.


Yeah I went down the separate objects route since that seemed like the simplest thing with OBJ files. I couldn’t figure out another way to annotate the specific verts that would need to move. Since glTF v1 and Ryan’s code support skeletons and skinning it’s a much more attractive option.