I'm on the look out for a Cor C++ library / SDK that will allow me to either write a 3d PDF directly, or convert a DXF or DWG into a 3D PDF. So far I have come up with the PDF3d library which fits the bill, but is reasonably costly and has an expensive per user run time license. I don't mind a reasonable SDK cost, but the per seat cost kills it for me.
Anyone aware of any alternatives?
I know that acrobat itself provides their free SDK 8.1 which supports 3d features as given in http://www.adobe.com/devnet/acrobat/pdfs/Acrobat_SDK_whats_new.pdf But I am not sure how much work is required to plugin for conversions. Hope this might work for you.
I use PDF XChange a lot for 2D CAD plots to PDF and it works well. I don't know if (I don't think so) it does 3D. I could find no mention of it at first glance on their site.
Your other option is a 3D DWF. Also consider that DWG TrueView is a free viewer and printer that handles 3D DWGs natively. You used to be able to automate TrueView through COM but I'm not sure if that is still so. Here is a blog post on some automation of Trueview - http://through-the-interface.typepad.com/through_the_interface/2007/10/au-handouts-t-1.html
I used PDFNet SDK (from PDFTron) to generate 3D PDF with embedded U3D and PRC files. The library is also available as a C++ library (on Windows, Linux, Mac). As a starting point I used U3D sample (http://www.pdftron.com/pdfnet/samplecode.html#U3D).
Btw, it seems that PDFTron PDFNet is used in AutoCAD and many other leading CAD applications (you may want to check their client list).