Blender exporter: facing direction inconsistent between geometry and scene exports. #7967
Description
In blender if I create an arrow facing down blenders positive Y axis and export it to load in a THREE.Scene. When I do it as geometry the arrow faces the negative Z axis, while exporting as a scene has the arrow facing the positive Z axis.
This is because when exporting only geometry, the geometry is rotated 90 deg about the X axis, while when exporting a scene the objects roots matrices are rotated 180 deg down an axis between the Y and Z axi.
I noticed this issue working on a patch to get the exporter to reinterpret all matrices and their geometries in the scene including child objects in the hierarchy instead of just the object root matrices, and so I wasn't sure what the preferred exported orientation would be.
I am actually of the opinion that the exporter shouldn't reinterpret the orientation at all, and just export from blender as is, and then have pipeline tools like grunt tasks that can reinterpret matrices, scale, orientate, change materials, etc, to a projects preferred metrics and settings. This falls in line with how Linus views Linux driver development, keep them as thin and simple as possible and let user-space applications/libraries do complex things with them. But this also means code is more accessible to javascript programmers, and they don't need to know as much about python if they want to change matrices, and these tools can be used for all geometry/scenes exported from any 3d program.