You can use line trace, and record points where it hits mesh.
Now how to get array of points that you can line trace to:
Easiest would be to make that static mesh into blueprint actor, then calculate grid of points in mesh local space.
If not you can try angles for vector. But this is a bit of vector math.
- first you need boundaries for that mesh. So either use trigonometry to find angle ranges, or just “scan” around and remember what angles get hits.
- when you have range, just make as much steps as you want, do line trace to points on surface of mesh, remember shortest.
However if its flat mesh you can solve closest point with just trigonometry or few vector operations.