Why is a curve circle not a nice circle?

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Goofster
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Why is a curve circle not a nice circle?

Post by Goofster »

is it just me or is a curve circle not a "perfect" circle?
I've compared it to a 100 vertice circle and it's still a HUGE way off. maybe this is one of those easy-to-fix things? (or maybe not :)

Roel

theeth
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Post by theeth »

and if you increase the resolution of the curve?

Martin
Life is what happens to you when you're busy making other plans.
- John Lennon

Goofster
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Joined: Mon Oct 14, 2002 12:26 pm

Post by Goofster »

nope, still nothing. (it was a good point though, I was very afraid that it was correct :))

for some more data:

in my opinion, the two top and two bottom Control vertices have to move away from eachother by 0.594
Last edited by Goofster on Fri Dec 06, 2002 3:51 pm, edited 1 time in total.

idefix
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Post by idefix »

As far as I know you cannot do an exact circle with bezier or spline because of the nature of circles which follow sin/cos relationships. So it will always be an approximation only.

Renzo

Goofster
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Post by Goofster »

ok, so why can I, a mere human edit the created curve circle in 2 seconds so it DOES look like a circle?

I nothing is perfect, but i've always wondered why the circle is so awefull. it's really anoying when you use a lot of curves like I do

o well, I'll try to find the code that makes the circle and edit it tonight (that will be my first actual dive in the code, wish me luck :)

Roel

wavk
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Post by wavk »

ARGH! That is bad. Needs to be fixed! By the way, how did you ever notice this, with your super human eyes?!

Goofster
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Post by Goofster »

don't all Dutch people have those?

anyhoo, I noticed it a long time ago, but it isn;t such a big thing that I would bug ton with it (instead I'm bugging myself with it now, long live opensource ey? :D )

just one of those things that you don't notice unless you look for it :)

Roel

xype
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Post by xype »

wavk wrote:ARGH! That is bad. Needs to be fixed! By the way, how did you ever notice this, with your super human eyes?!


Heh, it's not that hard to notice - the "curve" sphere isn't really a "circular sphere" either - I for my part solved that by not using curves for circular stuff.

Also I managed to adjust the curves to resemle a circle but decided it takes too much time so instead I was working with 64-vertex circles.. 8)

Goofster
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Post by Goofster »

hmmm, and of course a subsurfed cuve isn;t a perfect sphere, so we shouldn't use that either?

I'm happy to say I use curves for about 30% of my modelling.
have you tried making strange holes in a 64-vert circle? (eek!)

Roel

xype
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Post by xype »

Goofster wrote:have you tried making strange holes in a 64-vert circle? (eek!)


alpha maps? dunno, i actually omitted doing holes, i have bad experience with booleans in blender, but for the fact that they taught me to use autosave set on 4 minutes...

theeth
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Post by theeth »

Goofster wrote:ok, so why can I, a mere human edit the created curve circle in 2 seconds so it DOES look like a circle?
you said it yourself, it only looks like one. Beziers and nurbs are cubic interpolation curves, and a good cosinus and sinus approximation only comes when using 6th and 7th degrees Taylor series.

Xype: isn't 4 mins the default setting for autosave?

Martin
Life is what happens to you when you're busy making other plans.
- John Lennon

Goofster
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Joined: Mon Oct 14, 2002 12:26 pm

Post by Goofster »

theeth wrote:.... Beziers and nurbs are cubic interpolation curves, and a good cosinus and sinus approximation only comes when using 6th and 7th degrees Taylor series.
Martin

ahhhhh....taylor series.....I see..... (ahem :) )

so the shape of the circle is defined by a function? hmmm, that would make it harder :)

Roel
Last edited by Goofster on Sat Dec 07, 2002 1:43 pm, edited 1 time in total.

xype
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Post by xype »

theeth wrote:Xype: isn't 4 mins the default setting for autosave?

I had it on 10 before I changed... maybe a really old user setting I never changed back then.

Eric
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Post by Eric »

xype wrote:
theeth wrote:Xype: isn't 4 mins the default setting for autosave?

I had it on 10 before I changed... maybe a really old user setting I never changed back then.
How old are you? :twisted:

xype
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Post by xype »

Eric wrote:How old are you? :twisted:
22

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