I am trying to do this...
... as featured in this post, but in blender 2.8.
The only way that I can get anywhere close is to create an ocean slightly larger in X & Y than the cube, but shorter in Z. Then add a boolean on the cube with the object as the ocean and the operation set to difference. However, I can then only remove the faces of the cube above the ocean once the boolean modifier is applied, which means that the animation won't work.
What am I doing wrong?
EDIT: Having downloaded blender 2.79 and added a boolean intersect to the cube I get similar behaviour to blender 2.8 when the solver is set to BMesh...
...but setting the solver to Carve gives me the desired result.
So it looks as if blender 2.8 (which has removed the solver Carve) cannot generate the desired result.
So the questions stands, how do you create a slice of ocean with an animated surface in blender 2.8?