Fix scene midpoint detection.
MaterialPreviewRenderer: always set depthmask=true, this fixes a visibility problem with some transparent materials.
Further simplify code to compute scene bounds.
Add ICameraController.SetPivot() and implement it for OrbitCameraController s.t. the scene orbits around the geometric center of the scene.
Merge branch 'master' of github.com:acgessler/open3mod
OrbitCameraController: SetPivot() now uses dirty flag.
Comment test code.
Updated to latest assimp-net version.
Improve logging formatting.
Heuristically ignore all-black diffuse material color on textured surfaces.
First draft of pivoting feature.
OrbitCameraController: revert pitch for mouse input to fix weird pitching.
Further work on pivoting feature, it now takes the center of the selected node.
Fix pivot computation.
Fix unintended assertions.
Highlight pivot in hierarchy view.