uberzev
 |
Here's what it would look like... (photoshop mockup)
Here's my current best attempt... (bias: 75)  |
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| Posted: June 28, 2006 2:37 am | ||||
| James |
I think it should be added maybe also the invert of it
 |
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| Posted: June 28, 2006 6:34 am | ||||
byRo
 |
For those (if any) interested in doing it by math
, the curve is:
sqrt( 1 - x2 ) The "1 - x2" bit is easy. I haven't found a solution for the sqrt(). (yet  )
Rô _________________________________
My favourite question is "Why?". My second favourite is "Why not?" |
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| Posted: June 28, 2006 9:39 pm | ||||
|
Vladimir Golovin
Administrator |
Currently, there is no circular arc curve in FF, but I think we can add one in the next or a subsequent update. It would look like this:
Circular Arc: Curve Component - Start: Grayscale Map (0...100), default = 0 - End: Grayscale Map (0...100), default = 100 - Minimum: Grayscale Map (0...100), default = 0 - Maximum: Grayscale Map (0...100), default = 100 - Invert: Checkbox, default = False |
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| Posted: June 29, 2006 3:05 am | ||||
|
uberzev
|
That looks good Vlad. I believe the key to a proper spherize (like the one in Photoshop) is the circular arc.
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| Posted: June 29, 2006 4:27 am | ||||
|
byRo
|
Now I have.
Problem solved. Although the output is a tone curve and not exactly a curve - but they are basically the same thing. Here you go. Rô  _________________________________
My favourite question is "Why?". My second favourite is "Why not?" |
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| Posted: June 29, 2006 9:25 pm | ||||
|
byRo
|
Don't have clue why the FFFolks chose +-30 as representing the sqrt/sqr functions - but it works fine.
Here is a pic of the arc-curve output used as an offset to draw an arc. Rô  _________________________________
My favourite question is "Why?". My second favourite is "Why not?" |
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| Posted: June 29, 2006 9:28 pm | ||||
|
uberzev
|
Just Brilliant byRo!
 |
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| Posted: June 29, 2006 9:35 pm | ||||
|
byRo
|
Thanks.
I'm looking forward to see what you do with this. 
Rô _________________________________
My favourite question is "Why?". My second favourite is "Why not?" |
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| Posted: June 29, 2006 9:42 pm | ||||
|
uberzev
|
Ok well I cracked Photoshop's "Spherize" formula. Here's what the curve looks like...
It can be made with byRO's method but with the gamma at 40/-40. Here's an interactive demo/snippet... http://uberzev.googlepages.com/PerfectArc.ffxml Anyway, once again amazing work byRo. Look for your brilliant technique to be featured in uberLENS 2.5 and other fine filters. |
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| Posted: June 30, 2006 3:54 am | ||||
|
uberzev
|
Don't know what you'd call that, maybe bulginess? |
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| Posted: June 30, 2006 5:06 am | ||||
|
Vladimir Golovin
Administrator |
Maybe something like "Arc Angle" or "Sector Angle"? For example, it could range from 0 (linear look) to 90 degrees (a circular arc). |
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| Posted: July 3, 2006 4:47 am | ||||
|
uberzev
|
|
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| Posted: July 3, 2006 4:58 am | ||||
|
uberzev
|
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| Posted: August 5, 2006 11:13 pm | ||||
|
Vladimir Golovin
Administrator |
Thanks  We've implemented the main parameter as a sector angle -- it ranges from -90 degrees (a concave arc) through zero (a linear function) to 90 degrees (a convex arc, as shown on the picture above). |
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| Posted: August 8, 2006 6:26 am | ||||
|
uberzev
|
grrr.... I wanted to be able to create an arc that would go past 90 deg. Guess I'll still have to use byRo's method.
|
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| Posted: August 12, 2006 1:55 am | ||||
|
Vladimir Golovin
Administrator |
Well, if we allowed it to go beyond 90 degrees, that would result in non-normalized amplitude (the curve height would be less than max when Sector is greater than 90 degrees or smaller than -90 degrees). And if we did a forced normalization in that case, the curve would not be a "Circular Arc" anymore.
By the way, what do you need this for? |
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| Posted: August 12, 2006 6:19 am | ||||
|
uberzev
|
Check this out... http://uberzev.googlepages.com/byRoArc.ffxml
Drag the "byRo Method" slider to to the right see the additional functionality I'd like to see added to the Circular Arc control.
|
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| Posted: August 12, 2006 9:41 pm | ||||
|
Vladimir Golovin
Administrator |
But this is not a circular arc -- this is just a bulged curve, like those produced by the Bias component. |
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| Posted: August 14, 2006 5:57 am | ||||
|
uberzev
|
Bump!
I'd like to be able to create an arc-curve that when extended past 90 deg becomes a Lamé curve. This is different than bias. (Should be similar to the arc tool in adobe illustrator) |
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| Posted: April 15, 2007 7:07 pm | ||||
|
Vladimir Golovin
Administrator |
Yes, here's a good page on it:
http://mathworld.wolfram.com/Superellipse.html I'll add this to the list. |
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| Posted: April 16, 2007 5:48 am | ||||
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uberzev
|
Thanks vlad.
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| Posted: April 16, 2007 5:49 am | ||||
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