From the Game Engine forums to this one because it relates to all users.
The decimate modifier is great for reducing polygons without changing the shape of an object so much. But I think something’s missing.
How about an option to keep sharp edges?
Let’s say an object has the Edge Split modifier already applied to it. Next, applying the decimate modifier will rip the mesh where the sharp edges are because geometries are decimated asymmetrically.
Would it be possible to make decimation take into account sharp edges so the geometry won’t break?
And of course, would anyone find this important enough to take up the challenge and develop the code?
Here’s an example of where we are standing now:
Edit: The issue can be avoided by Removing Doubles (and Recalculate normals) before Decimating. Only trouble then is that all sharp edges have to be marked again for the Edge Split Modifier to make sharp edges. So maybe rephrase the question. Would it be possible not to lose ‘marked’ sharp edges after decimating?
Edit2: It seems that ‘marked’ seams are not lost after decimation, so it should be possible to have the same for ‘marked’ sharp edges.
Edit3: Planar Decimation has the Delimit option for Seams, so this might be the best alternative. It gives the best results though you have to mark all sharp edges as seams first. Guess this is solved for me. But because I like the Collapse more (gives smoother results) I hope such a Delimit option would be added to it in the future.