On Sat, Sep 25, 2010 at 6:28 PM, Ganeshram Iyer <[email protected]> wrote:

>> Defining the look/layout/feel for what a given 2D 'blueprint' might be
>> like.  What syntactic, semantic, pragmatic information could be and needs to
>> be included?  What would an example sheet look like (exact prototype
>> mock-up)?  Are there existing drafting document standards that we could
>> conform to?  Should we?  What does STEP have to say about standard drawings
>> and drafting formats?
>
> I will initially be looking to do the leg-work to research the standards,
> current practices and competitors' approaches on how the 2D drawing
> generator could/should be done.

Well, as to standards, I can't say how useful they would be (if you
can even get ahold of them) but it looks like parts of ISO 128 and
other standards related to it probably apply:
http://en.wikipedia.org/wiki/ISO_128

Unfortunately they're quite expensive, so it might be worth checking
with a local university library or even local library system to see if
they can track down copies.


When it comes to the details of getting the actual 2-D lines from the
3D geometry, that topic has been the subject of some recent SIGGRAPH
papers studying how artists depict 3-D shapes - their website has the
articles: http://www.cs.princeton.edu/gfx/proj/ld3d/

There was also a very good SIGGRAPH class on lines from 3-D models:
http://www.cs.princeton.edu/gfx/proj/sg08lines/


Actually generating the lines outlined in the above talks from our
geometry is somewhat more specific to BRL-CAD's internals - we have
some basic ability to generate a small subset of the lines described
in the above talks but I'll defer to Sean on whether it would be
better to examine that code first or "start clean", as it were.

My vague notion would be to design some kind of library API around the
line generation approaches outlined in the above papers/classes, and
then build tools to generate actual drawings according to the
standards using the drawing API, but as I am not in any sense familiar
with the ISO standards or the low level details of generating the
lines from the models those are just thoughts to be considered or
rejected as more research defines the task and subtasks more clearly.

As for more general "open source" work, I expect Sean has probably
already given you good advice, but I'll add my two cents - commit
early and often.  Don't hold back everything until it's done - even
partial efforts are often enough to inspire other people to
contribute, and incremental progress towards the goal is worth
preserving.  We use the subversion software for version control, so
basic familiarity with that will be helpful.

Welcome to the project, and best of luck with your efforts!

CY

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