Using FreeFEM for Numerical Integration

I am new to FreeFEM but am looking for help with a 3D numerical integration. My dataset currently has x,y,z and f(x,y,z) for a total of 4 values per point. For my testing, I am applying a simple formula (such as x^2 + y^2 + z^2) just to verify that the int3d will work for my style of data.

Any help or suggestions would be appreciated! I was able to make a mesh using the cube function and integrate the mesh, but am not sure how to apply the formula on the elements to then apply the int3d function on the edited mesh.