Subject:
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Re: Lsynth thoughts.
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Newsgroups:
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lugnet.cad.dev
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Date:
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Wed, 28 Apr 2004 03:42:12 GMT
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Viewed:
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1307 times
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In lugnet.cad.dev, Don Heyse wrote:
> 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.
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.
>
> > 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.
Don, the splining algorithm gives us *no* control over the distance between the
resulting spline points. They get farther apart the tighter the curve, and
closer together when the curvature is lower.
I'd like to study the algorithm that Frederick Glockner uses for true length
hoses. I believe it uses an iterative splining approach.
>
> > 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.
Examples?
>
> 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?
I like the idea of reusing LS00.DAT as much as possible. I'm not sure what the
advantage is to having different constraint types for different hose types.
>
> 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.
Well, the start and end points are at the LS00.DAT (isn't it obvious? LOL)
/ \ head
] [ stem
[_] base
The origin is where the base meets the stem.
Jennifer Clark suggested that we could put a disk between the base and stem to
indicate the origin of the part.
>
> > 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...
Any input on a format will be warmly welcomed.
>
> Don
Kevin
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Message has 1 Reply:
 | | Re: Lsynth thoughts. [DAT]
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| (...) I've only looked at the hoses so far. So I don't even know what the current algorithm for rubber bands looks like, much less how to improve it. (...) True, for my first cut at the fixed length length rubber hoses I calculated the total spline (...) (20 years ago, 28-Apr-04, to lugnet.cad.dev)
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Message is in Reply To:
| | Lsynth thoughts.
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| (...) 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. (URL) also tinkered with simulating 208c01.DAT fixed length chain links as a hose. I think it might work (...) (20 years ago, 27-Apr-04, to lugnet.cad.dev)
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