User:Phoenix/GSoc2012/Proposal
Contents
Project title
Implicit to NURBS conversion
Brief summary
At present, BRL-CAD has implemented lots of geometric primitives in a implicit form, but when it comes to interactive shaded displays and conversion to other formats, the disadvantages of implicit primitives come out. So we need a conversion to NURBS bundary representations. Lots of primitives have already been implemented as NURBS, but some are not robust and some still need to be improved. This summer, if I'm accepted, I'm going to accomplish the goal of converting all (if needed) implicit primitives to NURBS, fixing the bugs and correcting the errors existing now, and add new conversions that have not been implemented yet. Finally, I'd like to build a converter that converts primitives in a CSG model altogether to NURBS forms. The original version is a good starting point, and I will take the current routines of BRL-CAD.
Detailed description
Introduction
Although I have read a few books on Computer Graphics, I'm not very familiar with NURBS/BREP before I started preparing for the application. These days I have read a lot of materials relevant and read the codes of BRL-CAD, so now I have a deeper understand of what I'm going to do in this project. Below is my detailed proposal for the project. The first part...
Works done in BRL-CAD
The conversion of implicit primitives to NURBS in BRL-CAD can be seen in functions rt_*_brep() in src/librt/primitives/, and the conversion of each primitive is done in a seperate function. The executable file csgbrep.exe can call most of them to produce NURBS represtations of many primitives.
This work is significantly dependent on the OpenNURBS library. The conversion of some implicit primitives such as sphere(sph), ellipsoid(ell), torus(tor), just call the relevant function in OpenNURBS to build the NURBS representation. The data structures to describe NURBS is based on OpenNURBS.
Although lots of work has been done in BRL-CAD already, some bugs still exist and the work is still located at the mathematical orgin. It may not work well if the parameters are changed in some occasions. And some primitives are still not included. The robustness need to be improved and the missing ones should be added.
