Compute Range for heightfield from Tops

[noodlehead]

I have a heightfield as part of an HDA that is remapped. If I manually press "Compute Range" in the Heightfield Remap sop it works.... but I need to do it from an HDA processor inside Tops.

I promoted the "Compute Range" parameter (button) on the HDA. It works. 

Then I get it inside Tops HDA Processor via the Update HDA Parameter button... BUT in there it comes as a checkbox. If I check the checkbox it does nothing.

How does one enable Compute Range from inside an HDA Processor node in tops?

If not, is there a way in vex to the the min and max for the voxels of the heightfield?

Thanks

Edited July 7, 2019 by noodlehead

[muxalko]

I use bbox(0,D_YMIN) and bbox(0,D_YMAX).