It would be nice to have an universal guide line.
As a result to Philippe's answer above I decided to try my original approach but without using any edge information at all. So by just looking at angles (acos'ed dot products actually) to decide to group stuff or not.
It works remarkably well, so well in fact I'm kinda glad I dropped the edges approach
![[Image: smoothTest1a.png]](http://www.melkert.net/img/mel/smoothTest1a.png)
This is using the (ludicrously wide) angle threshold of 60 degrees, could probably lower that to 30 or so, haven't decided on that.
Downfall is things go 'weird' with high details on a curved surface, like minfig heads which seem to have a crumbled paper thing going on. I'm not complety sure this is the result of the general algorithm or a minor bug on my side.
![[Image: smoothTest1b.png]](http://www.melkert.net/img/mel/smoothTest1b.png)
But in general this approach's results ares very acceptable given the cost. Could probably optimize things to bring it at a loading level only slightly slower then the current LDCad loading times.
If we are serious about helping smoothing by introducing rules on the library, some kind of hint system would be most useful. Like: these following triangles all lay on a curved quad. A bit like the texture projection hints. This would make it possible to generate normals based on a common (cylinder) center instead of the surrounding triangle normals.
As a result to Philippe's answer above I decided to try my original approach but without using any edge information at all. So by just looking at angles (acos'ed dot products actually) to decide to group stuff or not.
It works remarkably well, so well in fact I'm kinda glad I dropped the edges approach
This is using the (ludicrously wide) angle threshold of 60 degrees, could probably lower that to 30 or so, haven't decided on that.
Downfall is things go 'weird' with high details on a curved surface, like minfig heads which seem to have a crumbled paper thing going on. I'm not complety sure this is the result of the general algorithm or a minor bug on my side.
But in general this approach's results ares very acceptable given the cost. Could probably optimize things to bring it at a loading level only slightly slower then the current LDCad loading times.
If we are serious about helping smoothing by introducing rules on the library, some kind of hint system would be most useful. Like: these following triangles all lay on a curved quad. A bit like the texture projection hints. This would make it possible to generate normals based on a common (cylinder) center instead of the surrounding triangle normals.