Subject:
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Re: Primitives to Hi-Res or not...
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Newsgroups:
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lugnet.cad.dev
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Date:
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Tue, 25 Jan 2000 08:34:34 GMT
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Viewed:
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691 times
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In lugnet.cad.dev, Paul Easter writes:
> Ok, Can some one tell me where we are heading with these Hi-Res primitives.
>
> I welcome all comments,
>
> Paul
My opinion is that we do need high res circular primitives (edge, disc, cyli,
etc) in cases where the part includes curves/surfaces with a significantly
larger diameter than 'usual'.
The good old STUD.dat (and its familiy) looks OK with 16 sided circular
primitives. But John Jensen's impressive 2951.dat bucket part proved that we
need 48 sided primitives to obtain acceptable resolution with larger a
diameter.
Further we might need even higher resolution primitives (96?, 120?) if we
start modelling curved train tracks or road patterned baseplates. ( I remember
that somebody had problems with that.)
My suggestion is to informally accept a rule of thumb (is it a right
expression?) that one side (or section) of the curved line/surface should not
be longer than cca. 10 LDU, measured when it is already built in the part
(i.e. not in the primitive itself). This looks nice when rendered in Ldraw or
Ldlite.
With this simple rule we could verify that the modelled curve/surface smooth
enough to yield an acceptable resolution when rendered.
Part modellers then will have three options:
1. Choose from the existing resolutions (16 sided, 48 sided so far)
[According to the above rule 16 sided primitives are good up to cca. 50 LDU in
diameter, while 48 sided prmitives are good up to cca. 150 LDU in diameter.]
2. Manually create a private subpart or use inlined curves/surfaces, if he/she
needs curve/surface with larger diameter or if the rendering performance is
not acceptable using official primitives.
3. Start officializing primitives with other resolutions.
This is only an idea, what do you think of it?
Bye
Ampi
---------------------------------------
Imre Papp
Geometria GIS Systems House
email: ipapp@geometria.hu
---------------------------------------
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Message has 2 Replies:
 | | Re: Primitives to Hi-Res or not...
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| (...) There are two issues here. a) what resolution is appropriate to realistically render a part, b) how are the circular features of that a likely to connect/interact with other parts or feature of the same part. Issue b) is why we cannot (...) (25 years ago, 25-Jan-00, to lugnet.cad.dev)
| | | Re: Primitives to Hi-Res or not...
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| In lugnet.cad.dev, Imre Papp writes: [snip] (...) [snip] One note about those curved tracks: Because of part details, circular primitives can't be used efficiently for modelling curved tracks. I refer to the tapering at both ends and the saw- theeth (...) (25 years ago, 25-Jan-00, to lugnet.cad.dev)
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Message is in Reply To:
| | Primitives to Hi-Res or not...
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| Ok, Can some one tell me where we are heading with these Hi-Res primitives. Today I created the Hi-Res versions of several of the "normal" primitives. Then I edited the main "normal" ones to use the Hi-Res instead. WOW! There was about a 10-20% (...) (25 years ago, 25-Jan-00, to lugnet.cad.dev)
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