Re: gEDA-user: )(

[Peter Clifton <pcjc2@xxxxxxxxx>]

On Fri, 2009-10-02 at 00:27 +0000, Kai-Martin Knaak wrote:
> On Thu, 01 Oct 2009 23:58:52 +0100, Peter Clifton wrote:
> 
> > As an older (code no longer in existence) example, perspective like this
> > is not hard to achieve:
> > 
> > http://www2.eng.cam.ac.uk/~pcjc2/geda/gerbv_GL.png
> > 
> > (That IIRC, is cairo-rendered onto a texture, then stretched onto a
> > quad).
> 
> IMHO, this is cheating. 3D objects would at least need ray tracing to 
> look half way real. If there is an urge to push 3D output of pcb layouts, 
> it would be wise not to reinvent the wheels. I'd suggest an export in a 
> 3D format and delegate rendering to a third party application like the 
> excellent blender.

IMO, this is _not_ cheating, it is a standard technique. The surface of
a board is flat - so you render it as one quad, and texture map the
surface.

Any real structure you wanted to represent (board edges, vias etc..)
would need more complex geometry.

I'd imagine that if you wanted to add a tiny bit of relief for copper
etching etc.. then you would use some other technique. I'm not an
expert, but something like "bump mapping" + lighting tricks might be
useful.

http://en.wikipedia.org/wiki/Bump_mapping

OpenGL rendering is not usually about correctness of geometry, or even
correctness of optical rendering - its about creating something which
looks acceptable, and still performs well.

Best wishes,

Peter C.




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