3D Interoperability

[sawarsi]

a question for the interop developers.

if i read an IGES file that contains a spherical surface entity type 196, i have noticed that the IGES specification is such that the u,v parametrizations are interchanged and that the outward pointing normal for the sphere is outside. when you convert to an ACIS sphere can you just set the reverse_v flag so that the ACIS sphere has the same outward pointing normal? is there anything else that needs to be done?

[bikash_parida]

I think reverse_v should be set to TRUE in this case, please check and let's know if it works for you.

[sawarsi]

yes, that is what i thought however, my question goes a little deeper yet. i want to convert this analytic sphere to an spline surface and i would like both the original analytic sphere and the spline surface to have the same normal direction. should i set the analytic sphere to have a negative radius so that it is considered "hollow" before i use bs3_surface_make_sph?

[bikash_parida]

Ideally the API you are using for converting sphere to spline should take care of surface normal during approximation. If that is not happening then it's a bug in that API.

[sawarsi]

no, it is not a bug in the API. please refer to my later post on the problems i have observed with converting files to the IGES format. i believe that the orientations in the IGES file are not correct in some instances.