My goal is to:
Flatten out a cube
Keep the cube's base on the same position of z-axis (i.e. flat on the ground plane)
Ideally, the volume of the cube should remain constant
Think of it like a block of clay slowly flowing out to the sides:
(High quality 2d sketch:)
So here is my scene: I have a "cube" (black object) and a lattice (orange object) that encapsulates the cube:
Selected the lattice with B
CtrlP -> Lattice Deform
Added Shape Keys under menu Data: Object Data
Then I tried to transform the cube with the lattice. Here is the result:
The way the cube is deformed is perfect, EXCEPT the base of the cube does NOT stay on the ground plane -- it gets pushed down below it.
So, my question is: how can I deform the cube like this, yet keep the base on the ground plane?