Selection question

V

Valued Ant

0
Selection question

Just one question: is it possible (short of writing a script) to make a circular selection in Cheetah? Say if you wanted to select all polygons in a shape or points on a spline within a certain radius; how might that be done?
 
Thanks, Pegot, but that's not what I'm looking for. I mean something like Photoshop's Elliptical Marquee Tool when you hold down the Option key: a selection that radiates out from a point (as opposed to Area Select's rectangular marquee from a corner).
 
I think ring-select is what you´re looking for - no?
A Photoshop Elliptical Marquee Tool is not available

Cheers
Frank
 

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Ring Select is good for connected polygons, but I wish to select points in a complex spline within a circular area. Ah well, I had to ask.
 
Valued Ant said:
Ring Select is good for connected polygons, but I wish to select points in a complex spline within a circular area. Ah well, I had to ask.
Click to expand...
You can select partially loops as well.
And paint select won´t work for you? Can we have a screenshot which illustrates this situation?

Cheers
Frank
 
It would be possible using a script to make a selection based on a spline or mesh. (Indeed, the easiest way to deal with a spline would be to convert it into a mesh.)

In fact I think a script to select all vertices of a given mesh that are inside or outside another mesh sounds very useful (and it would be even nicer if you could use on in C3D's creator/modifier chains — allowing application of modifiers to partial meshes).
 
OK, here’s the long version…

I’ve created a set of sine-wave splines, interspersed with each other, combined into one complex spline. Put this in a sweep creator with a circle or n-gon, add a nice material, and you get a good wire grill. (Pics 1 and 2)

What I’d like to do is reshape these splines into a hemisphere shape, much like the magnet tool (set to ‘circular’) does with polygons. Why? In order to make Pic. 3.

To make the wire grill of a microphone, you have to push the spline points into a hemisphere shape while still keeping the same arrangement between the ‘up’ and ‘down’ points. From what little I’ve read on the ‘net, other 3D programs do this by ‘attaching’ the splines to a plane, distorting the plane to a hemisphere, then copying the re-shaped splines, but Cheetah has not this ability. Creating a sweep and using polygon modifiers isn’t an option, as the polys tend to get distorted at the edges and it’s hard to get the correct shape. What I want is a way to re-shape the spline, then add the sweep.

So I had the idea of making ever-decreasing circular selections of spline points and raising them to match the contour of a hemisphere. To illustrate this, I carried out a similar process with Area Select. I placed a half-cylinder over my spline. In Bottom View, I used Area Select to make a square selection of almost all the points in the spline. I activated the Transform tool, fixed the gadget to one of the outer points of the selection in Gadget Mode, then moved the selected points up until the outer points intersected with the half-cylinder. In Bottom View again, I made a smaller selection with Area Select (one ‘row’ in from each side) and repeated the process. I kept going until I’d worked to the central points of the spline (Pic. 4). Pic. 5 is the result. Note that each ‘wire’ is the same diameter throughout.

If I could do the same with circular selections, radiating from the centre, I reckon I could make my microphone grill. Area Select’s rectangular selections won’t do the job. Hand- or paint-selecting points is fiddly and likely to be inaccurate. Expand/Reduce selection only works along one ‘wire’ and won’t spread out in a circular pattern. I’ve experimented a little with Rope and Anchor Tags, but they seem to distort the spline way too much (although they might be good for making hedgehogs).

So, has anyone a way to make circular selections in Cheetah? Or a magnet tool for splines?
 

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I am on a holiday and far away from a usful iMac, so I can´t test this:
Would the spherify modifier not be the proper tool for this?
 
The Modifiers only work when polys are formed around splines, and they tend to distort the polys. The above picture shows the effect of the Spherify modifier, which isn't impressive. The below picture shows the Warp modifier, set to Spherical, in action. Looks a little better, but still not what I'm looking for; notice how the polys near the end are focusing onto a point and thinning to nothing as they do. What I'm after is a way of reshaping the splines on their own first.
 

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Someone on the Lightwave forum used cloth dynamics to drape their mesh over a sphere. Might give that a try.
 
The only dynamic tag you can attach directly to splines is the Rope Tag. I'm pretty ignorant on animation and dynamics, and, as you see, my experiments connecting the wire mesh spline to a Rope Tag haven't been promising. Possibly some combination of Rope and Anchor Tags may work, but I haven't figured it out.
 

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I've tried two bend modifiers with similar results, one works fine but two introduces distortion.
I agree, if the modifiers worked on the splines, that would eliminate the distortion problem.
Illustrator doesn't have any 3D tools to speak of, we need a 3D oriented spline drawing program.

​
 

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I noticed a three quarter view helps to eliminate the distortion.

This one looks OK but is still distorted.
I used the Bend and Bulge modifiers.

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Yes, ZooHead, you can get away with gentle Bend (or cylinder Wrap) modification, and probably other Modifiers if used carefully. I like your renders, by the way. What's your lighting set-up?
 

Thanks Valued Ant, I used the HDR images that came with Cheetah for lighting.
I make variations of them to change things like white point to change the lighting color.
(Here's a link to- entrancehall white.hdr)
I came from a time before image based lighting and I used to
have virtual studios set up so I wouldn't have to set up lights
every time. Now with a good HDR image, I may
occasionally use one light for fill.

​
 
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