Window glow mod: Collision issues
Mod download: http://max99x.com/morrowind/windows-glow
Copied from Pherim's forum thread (https://forum.openmw.org/viewtopic.php?f=2&t=2580):
[Pherim talking about issues at the Ghostgate] "[...]When I tried to enter the lower level of one of the domes I discovered that I couldn't, as if an invisible object was blocking me. I didn't understand at first why this would happen, as it didn't happen in original Morrowind (the very same installation that I'm running OpenMW with). When I enterend tcg to display the collision geometry (by the way, this does not seem to work in original Morrowind to me although it is described as a console command on the UESP) I saw horizontal lines crossing the entrance, as if there was a collision mesh. It took me a while to discover the cause: The windows glow mesh of the dome has a collision mesh with unapplied translation values (The NiTrishape inside the RootCollisionNode, not the RootCollisionNode itself, and somehow, the Game does not handle that correctly and places the collision mesh where it would be if all translation values were 0. After I applied them to the NiTrishape, collision worked fine again ingame. The stange thing about this is that the RootCollisionNode is exactly the same as in the original mesh, including the translation values. However, the game handles the collision correctly on the original mesh, as the way is not blocked at night when the Windows glow mesh is disabled. I have no idea what could be causing this.
And there is another thing I discovered: As you probably know, if there is no RootCollisionNode present in a mesh, the actual geometry is taken for collision, which is no problem for the low-poly meshes in Morrowind that are like this, but there are a number of mesh replacers out there (and also in MGSO) which subdivide the original meshes to make them smoother, but as a result they have much, much more polygons than the originals. In most cases I know the authors did not add RootCollisionNodes to meshes which don't have them but take into account that the now very complex geometry of the entire mesh is used for that (maybe they are even unaware of that). An example of that are the urns included in MGSO. Now I discovered that while I have mostly 25-50 FPS in interiors in OpenMW with MGSO installed, the framerate drops to 1-3 when I run against these urns, while in original Morrowind there is no change in FPS at all. It would appear that collision detection is still very performance-heavy in OpenMW, but you are probably aware of that. By the way, it would be quite easy for modders to avoid this by simply keeping the originals as RootCollisionNodes for the smoothed meshes - When I did that with the urns the performance drop in OpenMW was gone entirely."
(RM-2123 from redmine: created on 2014-11-14 by Thomas Staudinger, , closed on 2015-01-13 by scrawl ., relates #1683 (closed))