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 CAD / Development / 9675
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Subject: 
Lsynth thoughts.
Newsgroups: 
lugnet.cad.dev
Date: 
Tue, 27 Apr 2004 16:43:34 GMT
Viewed: 
1175 times
  
In lugnet.cad, Kevin L. Clague wrote:
In lugnet.cad, Don Heyse wrote:
Anyhow, I suppose I could just check the changes into CVS and see if
anyone notices. ;^)

Well, I have to get hooked in and put in a few of my changes as well.

Please do.  I got to tinkering over the weekend and added some code
to generate the fixed length 50 segment 751.DAT style rubber hoses.

  http://ldglite.sourceforge.net/lsynhose.png

I also tinkered with simulating 208c01.DAT fixed length chain
links as a hose.  I think it might work well with the end
constraints pointing down to simulate gravity.  Obviously you'd
need more constraints to simulate draping a chain over something.
And maybe the constraint for a chain should look more like a link.

Another thing I'd like to do is stop hard coding constraints and
synthesis parts into LSynth (at least for band synthesis), and move
those controls externally to a file.

Yes, this would be nice if you could make lsynthcp entensible without
recompiling.  Just read the config file.

Defining part/radius/orientation for bands should be easy.  Defining
cross sections and end parts for hoses should be easy too.

There are a few things that control hose synthesis; hose type, hose
segment part type, segment orientation, segment diameter, and the
constraints.

Don't forget total number of segments for fixed length hoses.  And
I'm not sure what you're including in "segment orientation", but
subsequent segments of Larry's fake string and subsequent chain
link segments are rotated 90 degrees from each other.  You'd need
language to control that.

I'd like a file format that defines a hose type name, and its
attributes (hose cross section segment, the oriention of the hose
axis in the cross section part, and the outer diameter of the hose).

We might also want some special condiftions for end of hose
issues. e.g. flared hose, or hose ends with special symbols on the
end so we can color code the hose ends, etc.

I'd also like to define the part types used for individual hose
constraints.  Eventually I'd like to add new hose constraint types.
For example, a constraint that says "you have to go through this
point, but I don't care about the orientation of the axis at this
point."

Yes, don't care constraints would make things simpler for many hoses.
I like the LS00.DAT hose constraints, but for some things it might be
easier to work with assumed constraints based on the parts located at
the hose ends.

Or would it be better for the program calling lsynthcp to have a
function which automatically creates the hose end constraints based
on the hose type and the fixed end parts?

Also, I had some trouble visualizing exactly where the hose would
start and end from the LS00.DAT constraint.  Maybe the actual
endpoints of the hose would be better illustrated by adding a bullseye
in a fixed color to the LS00.DAT constraint.

For band synthesis, I'd like to be able to define band types: round
cross section rubber bands, square cross section rubber bands, new
technic chain, old technic chain, plastic linked tread, rubber
tread.  For each type, I'd like to define the cross section part,
its orientation, diameter (if apropo), etc.  > For band constraints,
we need to know the part type, its diameter (or radius), and its
orientation.

I don't think the above looks like stuff that goes into an LDraw
file format, unless we introduce a whole bunch of meta commands.
When it is this far off, is it worth forcing it into the LDraw file
format?  I suppose the advantage is that people can define their
hose type directly in an LDraw file and have it ported around with
it.  Hmmm...

I agree.  Hmmm...

Don



Message has 1 Reply:
  Re: Lsynth thoughts.
 
(...) Yes, then lsynthcp can focus on the synthesis algorithms like spline, and belts. I'd love to have an algorithm for non-planar rubber bands. (...) Don, the splining algorithm gives us *no* control over the distance between the resulting spline (...) (20 years ago, 28-Apr-04, to lugnet.cad.dev)

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