I'm trying to cut a triangular pyramid precisely into two pieces, a lower base part and the upper tip, as shown by the blue lines in the picture.
Vertices A B C must have the same exact z-coordinate. So when the tip is cut away it will leave a perfecly flat (non-angular) surface.
I've tried subdividing and sliding vertices (Shift V) and trying to snap to a vertex in another mesh (with the required z coordinate), but its semms there is no vertex snapping for slide operations.
I also tried bevelling the top vertex to 0.0001 which allows using Edge loop and slide, but the same issue then occurs, ie no vertex snapping.
I could just add the vertex on each edge and then manually slide into place until I see the exact z coordinate, however I need to do this many times and it is relatively slow and error prone.
Is there a builtin way (or add-on) that simply lets us cut an object into two pieces precisely?