# After a deformation operation on polygons, how can I check for and fix inverted polys?

I'm doing a quick and dirty automated deformation routine on a polygon body. If it was a tree, and my axis was in the center of the tree, I would like to bend the body by bending the axis. I would use a simple influencing algorithm to determine vertex point xyz displacement.

On the concave side of the bend, how can I check for polygons that have overlapped or passed through each other, and how can I fix such polygons?

Thank you!

• Could you maybe add an example mesh and how it's being transformed? If you're actually moving the vertices, not the individual polygons, I'm not sure why they would pass through each other from a simple bending operation. Shouldn't the polygons on the concave side just shrink a bit? Commented Nov 20, 2015 at 9:12
• @MartinBüttner By the sound of it, he/she will get a similar problem to that of doing offset curves when the offset exceeds the radius of curvature. e.g. look at the inner set of green curves which have been displaced too far from the red. Commented Nov 20, 2015 at 10:44
• Seems to me the subject lines ask about recalculating normals while the body asks about self intersection. Commented Nov 20, 2015 at 12:50
• I am sorry, my subject and body are not coherent. This is because I am not sure of the exact terminology to use. I think Simon F has interpreted my question as I intended though; I need to figure out how to handle the situation where the offset exceeds the radius of curvature. I will upload a sketch momentarily. Commented Nov 20, 2015 at 16:16
• Ah yes, theres really nothing you can do about this kind of things except not bend too much. Commented Nov 20, 2015 at 20:53