As it turns out, enumerating a collection that can be modified is a bad
idea. Indeed, Blender expects that we won't do this. Sometimes, it
appears to work, however, other times, Blender is unable to handle it
and the internal data gets corrupted, causing a crash.
This commit includes some bonus improvements for animated parenting
situations that I discovered through sciencing the various MOUL and PotS
PRPs. Hopefully it all works as advertised.
This causes an object to be given a plFilterCoordInterface instead of a
plCoordinateInterface. The difference is that plFilterCoordInterface
will reject changes to certain components of an object's transform. This
is useful in certain parenting situations, namely subworlds.
Somewhere around Blender 2.75, the SCONS build system was removed and
CMake reigned supreme. The installer was of course changed to a Windows
Installer generated by CPack. Unfortunately for us, the registry keys
changed. Windows Installer's registry stuff sucks, but this is the
easiest way for us to get at it.
Not sure why this was happening, but if you got into a state where no
VisRegion was selected, the Environment Clear Color property would also
disappear.
Reordered to put the Clear Color at the top, so that it works
consistently and also makes it more obvious that it's unrelated to the
visibility regions.
We're only a BlendSpan if the *first* layer of a material has a blend.
Other layers are permitted to have blend modes, because those don't
affect the blending of the span itself against other spans.
This matches the behaviour of PlasmaMax:
42c4acbc9d/Sources/Tools/MaxConvert/plMeshConverter.cpp (L1205-L1210)
If certain modifiers are applied during the bake process, the resulting
lightmap is fullbright. To solve this, we cache the modifier data, clear
them away, then bake. When the export is completed, we then restore the
modifiers.
