For a papercrafting application I need to decimate (collapse) the geometry in order to reduce the number of faces. The original geometry looks like this:
When applying the decimate modifier (with triangulation), I noticed that the flat base of the spherical dome is not planar anymore:
I want keep this face planar (which is intentionally so in order to be glued to something else) while collapsing.
Is there a way to constrain the vertices of that face such that the decimate modifier will be able to move them only within the plane of that face?
Since I'm still a newby to Blender, I wouldn't know where to look for a solution. My searches for obvious keywords did not surface anything that looked applicable to my problem.