Decal geometry with child geometries

Questions
1

I’m loading a model using objloader and my model include several child geometries.
I would like to project an image on the model same as demonstrated in the decal example (https://threejs.org/examples/webgl_decals.html)

however when I’m trying to add the decal on the model, the decal object expect to get a mesh with geometry, and my model object contains several child geometrie and this is not working. if I’m using only one of the child geometries it is working - but then the projection is not correct as it should be projected on all.

how can I support the child geometries when using decal?

3

I updated the post with more details

4

You would have to enhance the implementation of DecalGeometry to support meshes with children. Instead of doing this, have you tried to merge your object hierarchy into a single mesh?

5

merging may be good idea, what would be the best way to do it?
assuming each geometry has it’s own textures

6

Would it be possible to merge the objects in a content creation tool? What kind of objects are we actually talking about^^?

7

not really an option…
I’ve got an obj model with textures (mtl).
I’m using the ObjLoader to load it - it’s output is an object which don’t have geometry property - but child objects. each child object has geometry (BufferGeometry)
I found the web samples for merging geometries but non of them handle the materials.
any idea how to do it properly?

8

You might want to check out BufferGeometryUtils.mergeBufferGeometries(). The second parameter useGroups can be used to generate groups for the merged geometry. Groups enable the usage of multiple materials per object.

9

Thanks, I’ll try