Subject:
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Re: The use of type 5 lines for smoothing of objects.
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Newsgroups:
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lugnet.cad.dev
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Date:
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Wed, 22 May 2002 00:32:21 GMT
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Viewed:
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721 times
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On May 08 Martijn Zwaal wrote in lugnet.cad.dev:
> Hello people,
>
> this is my first post. A few weeks ago I mailed with Travis Cobbs and Lars
> Hassing about an algorithm I constructed to make objects look smoother. This
> can be done by using per vertex normals and smooth shading. The normals can
> be calculated with the data contained in the 'type 5' lines, because they
> mark edges that are smooth in the real world.
Hi Martijn,
that's a brilliant idea!!
I have always regarded optional lines as only a mean for drawing
the outline/contour on curved surfaces.
But optional lines are actually a valuable information
about where surfaces are curved.
Obvious once you think about it :-)
Before you presented your algorithm my initial thoughts went into the same
direction as Travis has later suggested:
Use the first two vertices of the LT5 to find adjacent surfaces and use their normals
to calculate the smoothing normals. I don't think the controls points are
of any reliable use.
However, I would normalize the normals because the size of the surfaces
may depend on how the object is triangulized and therefor doesn't necessarily
indicate any dominance on the normal.
Also I think you have to calculate per part and not just per datfile.
In L3Lab I have made an option to internally convert all lines and
surfaces to vertex lists. This should save some transformation
calculation, but the transformation time is not my bottleneck
(the rendering is, because I do it in software), so it only gives
1-5 % speed up.
However, for this purpose I think this preprocessing would be
advantageous, because the map can be reduced to a vector (simple array).
Your program looks great and promising, and so does Travis's image.
Using e.g. keystrokes 'n' and 'p' would help users without a mousewheel.
I look forward to experiment with this new usage of LT5
when I hopefully soon get some spare time. It would a great option to L3P.
/Lars
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Message is in Reply To:
 | | The use of type 5 lines for smoothing of objects.
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| Hello people, this is my first post. A few weeks ago I mailed with Travis Cobbs and Lars Hassing about an algorithm I constructed to make objects look smoother. This can be done by using per vertex normals and smooth shading. The normals can be (...) (22 years ago, 8-May-02, to lugnet.cad.dev)
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