Draws points at a list of 3D positions.
Update the data displayed by this item. All arguments are optional; for example it is allowed to update spot positions while leaving colors unchanged, etc.
Arguments: pos (N,3) array of floats specifying point locations. color (N,4) array of floats (0.0-1.0) specifying spot colors OR a tuple of floats specifying a single color for all spots. size (N,) array of floats specifying spot sizes or a single value to apply to all spots. pxMode If True, spot sizes are expressed in pixels. Otherwise, they are expressed in item coordinates.