[Closed] Create a extrude upto surface function without using boolean op

I want to create a extrude upto surface function without using boolean operation.
Because boolean always cause problems.
Do anyone provide me any idea to make such a function (extrude a spline(or shape) upto the surface and this surface is not a planar surface, so the projected shape is not the same as the original )?
i know mergeshape can do the projection, but how to connect two shapes?
Or anyone hv any new idea on it?
please help
thx