When I create a polygon geometry with the perPositionHeight, and extrudedHeight attributes/options set, what is rendered on the screen is a polygon which goes down to the ground. The polygon extrusion/top appears correctly. I would have thought that the polygon base would have respected the perPositionHeight attribute as well. The height of each basepoint would be the position height of the corresponding point.
The current implementation of PolygonGeometry only applies the perPositionHeight to the top of the extrusion. You can modify PolygonGeometryLIbrary.scaleToGeodeticHeightExtruded to change this.
In this function, minHeight is the height of the bottom of the extrusion and maxHeight is the height of the top. Currently, if perPositionHeight is true, maxHeight is added to the height of the top position (lines 87-91). Bottom positions are scaled to the surface of the ellipsoid then minHeight is added to that position (lines 79-82).
Hey Patrick, please start a new thread for a separate topic/question. That’ll keep things organized. I think this is a good question that you should start a thread for, and I’d be happy to put together a full response there so people can easily find it in the future.