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The lathe object can use linear, quadratic, cubic and bezier splines. The
SOR object uses some unnamed spline type.
I have some questions.
Suppose that I want to draw (just in a plain 2D graphic window) a qudratic,
cubic or bezier spline given the control points.
Can someone tell me the algorithm used to calculate the curve for each type
of spline? Preferably I would like to get all the points that will form a
contiguous curve in the drawing bitmap (no gaps and no points drawn in the
same place) given the resolution of the drawing window, but also a less
perfect solution is ok.
Also I would like an algorithm to draw the spline curve used by the SOR
object, given the control points.
--
main(i,_){for(_?--i,main(i+2,"FhhQHFIJD|FQTITFN]zRFHhhTBFHhhTBFysdB"[i]
):5;i&&_>1;printf("%s",_-70?_&1?"[]":" ":(_=0,"\n")),_/=2);} /*- Warp -*/
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These algorithms are rather involved, you should check your library for
books on the subject.
In the one I have (CAD/CAM theory & practice, MCGraw-Hill 1991), the
mathematical explanation of splines and Bezier curves takes about 20
pages. A bit too long for this ng.
Nieminen Juha wrote:
>
> The lathe object can use linear, quadratic, cubic and bezier splines. The
> SOR object uses some unnamed spline type.
> I have some questions.
>
> Suppose that I want to draw (just in a plain 2D graphic window) a qudratic,
> cubic or bezier spline given the control points.
> Can someone tell me the algorithm used to calculate the curve for each type
> of spline? Preferably I would like to get all the points that will form a
> contiguous curve in the drawing bitmap (no gaps and no points drawn in the
> same place) given the resolution of the drawing window, but also a less
> perfect solution is ok.
>
> Also I would like an algorithm to draw the spline curve used by the SOR
> object, given the control points.
>
> --
> main(i,_){for(_?--i,main(i+2,"FhhQHFIJD|FQTITFN]zRFHhhTBFHhhTBFysdB"[i]
> ):5;i&&_>1;printf("%s",_-70?_&1?"[]":" ":(_=0,"\n")),_/=2);} /*- Warp -*/
--
Francois Labreque | The surest sign of the existence of extra-
flabreq | terrestrial intelligence is that they never
@ | bothered to come down here and visit us!
attglobal.net - Calvin
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A very good place to read about bezier curves and bezier patches is
http://graphics.cs.ucdavis.edu/GraphicsNotes/Graphics-Notes.html
I hope this may help you.
Alberto.
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On 12 Mar 2000 08:00:15 -0500, Nieminen Juha
<war### [at] sarakerttunen cstutfi> wrote:
> Also I would like an algorithm to draw the spline curve used by the SOR
>object, given the control points.
I suppose the SOR object uses a polynomial spline. I will try to find
the algorithms for the Newton / Lagrange interpolation polynoms for
you.
Peter Popov
pet### [at] usanet
ICQ: 15002700
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Alberto <jac### [at] usbve> wrote:
: A very good place to read about bezier curves and bezier patches is
: http://graphics.cs.ucdavis.edu/GraphicsNotes/Graphics-Notes.html
Thanks. However it only explains the bezier curves (which are actually the
ones I less need, unfortunately). Thanks anyways.
--
main(i,_){for(_?--i,main(i+2,"FhhQHFIJD|FQTITFN]zRFHhhTBFHhhTBFysdB"[i]
):5;i&&_>1;printf("%s",_-70?_&1?"[]":" ":(_=0,"\n")),_/=2);} /*- Warp -*/
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This seems to be one of those things that nobody knows how to do it. I
have tried searching in the www, but nothing.
Isn't there really ANY info about it?
Thinking about it, the points don't need to be at equal distances, as long
as there are some points at the curve. I can draw lines between them. If there
are enough points it will be a good enough approximation.
--
main(i,_){for(_?--i,main(i+2,"FhhQHFIJD|FQTITFN]zRFHhhTBFHhhTBFysdB"[i]
):5;i&&_>1;printf("%s",_-70?_&1?"[]":" ":(_=0,"\n")),_/=2);} /*- Warp -*/
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In article <38ccd50a@news.povray.org>, Nieminen Juha
<war### [at] sarakerttunencstutfi> wrote:
> This seems to be one of those things that nobody knows how to do it. I
> have tried searching in the www, but nothing.
>
> Isn't there really ANY info about it?
> Thinking about it, the points don't need to be at equal distances, as
> long as there are some points at the curve. I can draw lines between
> them. If there are enough points it will be a good enough
> approximation.
If this is in MegaPOV, you could scan the surface with the trace()
function...
--
Chris Huff
e-mail: chr### [at] yahoocom
Web page: http://chrishuff.dhs.org/
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Nieminen Juha wrote:
> Can someone tell me the algorithm used to calculate the curve for each
> type
>of spline?
Not sure if this is what you are looking for, do a search at Deja for Steve
Noskow in c.g.r.r. In the result start with the first post from the top. He
may be the person who can help you.
Ingo
--
Photography: http://members.home.nl/ingoogni/
Pov-Ray : http://members.home.nl/seed7/
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ingo wrote:
>In the result start with the first post from the top
Sorry, I meant third post.
http://www.deja.com/dnquery.xp?ST=QS&DBS=1&groups=comp.graphics.rendering.r
aytracing&QRY=Steve+Noskow&svcclass=dnold
Ingo
--
Photography: http://members.home.nl/ingoogni/
Pov-Ray : http://members.home.nl/seed7/
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Chris Huff <chr### [at] yahoocom> wrote:
: If this is in MegaPOV, you could scan the surface with the trace()
: function...
No, I just want to make this in my own (2D) program.
--
main(i,_){for(_?--i,main(i+2,"FhhQHFIJD|FQTITFN]zRFHhhTBFHhhTBFysdB"[i]
):5;i&&_>1;printf("%s",_-70?_&1?"[]":" ":(_=0,"\n")),_/=2);} /*- Warp -*/
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