Looking for Points Within a Certain Distance

For a level-of-detail algorithm I am writing I need to find all points within a certain distance from the camera. Right now I have a ray in an update loop which is looking for collisions with my geometry. As of now I am simply finding the distance the camera is from the closest point. Also I was wondering if it was possible to only have the ray collide with coordinates that are defined in the geometry. For example on a mesh which only has the coordinates (0,0,0)(0,0,1)(1,0,1)(1,0,0) the closest point is frequently described with the x and z coordinate shown in an extensive decimal form.
Thanks for any help.

Never mind, I figured something out.