On Sep 17, 2015, at 9:19 AM, Q <godbles...@gmail.com> wrote: > Thank you Sean. I always find your post very informative.
I try, thanks. As you can tell, I can’t always reply timely, but I try to be helpful and write a proper response when I can. :) > But how can an offsets be a trivial surface and/or object move? If the curve > is not straight, an offset will need some shape changes. A dilation of an > ellipse is not an ellipse anymore(just to illustrate my point, I could be > wrong), then will BRL-CAD automatically generate new primitives to represent > the new geometry? It depends entirely on the shape and the target result, but your concerns are certainly valid. In general, a completely different modeling approach is recommended whereby a target shape is examined for gross characteristic and directly modeled using appropriate primitives and Boolean operations. You model the overall shape and fit target surfaces using underlying primitives. Sometimes this is far more effective than a parametric interactive surface modeling approach and sometimes it’s not. The dominant factor is having a variety of primitives to work with, experience joining them together, and experience describing Boolean operations beyond simple unions and subtractions to fit a shape. The Principles of Effective Modeling book in our Docs covers some of this in more detail. > I see nurb and spline are still missing, so I guess we can only approximate > very irregular surfaces like a computer mouse or tea spoon with polygons > patches, it would be disastrous to change all these small patches one by one > if I want modifications. BRL-CAD has full NURBS representation support now, but does not yet support surface editing. That said, the examples you provided are probably attainable (depending on exact tolerance requirements and shape complexity) using various advanced combinations of primitives, but devil is obviously in the details. To be honest, though, unless you are very proficient, incremental modifications beyond increasing or removing detail will probably be difficult. > In my opinion, command line and keyboard are more attractive than fancy GUI > and mouse interactions, it gives us more precise control and less eye strain. I agree. ;) Merits to both, though, of course. GUIs excel at information resolution. We want (and do not yet have) a GUI that really simplifies the geometry creation and editing process, with exceptional focus on usability, simplicity, design, and discoverability that sits on top of a powerful and flexible CLI (which we do have) that exposes full capability. > Lastly, I find the model share page(http://more.brlcad.org/popular-models) > is still broken. Maybe a repository on github is a better place for those > files. Storing the files is no problem. The desirable goal is an online repository where you can browse through models, download them in different formats, spin them around in the browser, etc. The 'MORE' effort was replaced with the Online Geometry Viewer (OGV) project that has been under development for the past couple years. The focus also shifted away from being a static repository to working the challenges of displaying/importing/exporting CAD geometry in a browser interactively. We had two GSoC projects going all summer to develop and stabilize the interface for public testing. It’s still a work in progress, but hopefully something we will unveil later this year — system administration issues are being sorted out to host the service. Cheers! Sean ------------------------------------------------------------------------------ _______________________________________________ BRL-CAD Users mailing list brlcad-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/brlcad-users
