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Hi Barry

There were a few issues where BPRISM deals with things differently to other commands. The main problem was that ARCHICAD facets BPRISMs completely differently. The attached image shows the original geometry (circle) with how ARCHICAD usually facets (inner hexagon) and an example facet for the bprism (triangle extending to the outside of the circle).

To get around the problem I had to:

– multiple the radius of the BPRISM by * cos(180/resolution)

– multiple the thickness of the BPRISM by * cos(180/resolution)

– rotate the BPRISM by 180+180/resolution along its axis

GS HQ also suggested using REVOLVE{2} alongside BPRISM, instead of the basic version of REVOLVE. It seems to be undocumented but REVOLVE{2} behaves in the same way as BPRISM when facetted, instead of like the usual commands.

However, I’m having a couple of other issues with REVOLVE{2} so you might hear more from me shortly!