Avoid extra rebuilds on param changes when nothing is picked
Avoid extra rebuilds on param changes when nothing is picked

Before this, `measureUpdate` would always pass `radiusData` to `setParameters`,
which would rebuild because it only checks for undefined.
This commit avoids calling `setParameters` if there's nothing to do, which
should speed up frame rate in some cases.

fredludlow/ngl,arose/ngl,fredludlow/ngl,arose/ngl,fredludlow/ngl,fredludlow/ngl,arose/ngl,arose/ngl