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Old 23rd June 2007, 03:03 PM   #1
Terry Capps
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Question Extrude along path with Non-Symmetrical surface?

I have been experimenting with using the Extrude-along-path with a non-symmetrical surface and I am having difficulty determining what the result is going to look like. Or, in other words, how to position the original surface and path to achieve the desired result.

An image of an example can be seen at :
http://img.villagephotos.com/p/2006-...rtingpoint.jpg

It consists of a Right-Triangle and a straight line path.

The result can be seen at:
http://img.villagephotos.com/p/2006-...pathresult.jpg

The center of mass of the triangle is apparently being used, but how the original surface is being rotated before the extrusion begins is a mystery to me.

Does anyone know anything about this?

Thanks,

Last edited by Terry Capps; 23rd June 2007 at 03:07 PM.
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Old 23rd June 2007, 03:53 PM   #2
Andy
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Default Re: Extrude along path with Non-Symmetrical surface?

Line the object up with the start of the path/line (as if it was going to be the first section) before you do the extrusion. This way, in the function, the profile won't need rotating much before it's moved along the path. (it will try and line the profile up so that it's perpendicular to the first section of the path)
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Old 23rd June 2007, 06:07 PM   #3
Terry Capps
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Default Re: Extrude along path with Non-Symmetrical surface?

Thanks, Andy

I tried that in the example, that I illustrated in my posting, by orienting the triangle so that it lie on a plane that was perpendicular to the defined path and the extruded sections lined up so that they became extensions of the original triangle.
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Old 23rd June 2007, 06:17 PM   #4
Andy
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Default Re: Extrude along path with Non-Symmetrical surface?

The line/path wants to be perpendicular to the object - your Top view shows that this is not the case. Switch on normals-display (press 'n') and use the normal from the triangle as a guide.
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Old 26th June 2007, 10:10 AM   #5
Terry Capps
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Default Re: Extrude along path with Non-Symmetrical surface?

Indeed! In addition, for a curved path, the first leg of the path must not only be perpendicular to the surface-object, but also must start at the center of gravity (base of the normal) if it is desired for the extruded object to end at the end of the path. The files attached illustrate what I mean. Extrude along a curved path1.jpg shows what happens if the first leg is perpendicular to the surface, and touching it, but isn't at the surface's center of gravity. Extrude along a curved path2.jpg shows what happens if the first leg is perpendicular to the surface, touching it, and at the surface's center of gravity.

http://img.villagephotos.com/p/2006-...urvedpath1.jpg
http://img.villagephotos.com/p/2006-...urvedpath2.jpg
Thanks,

Last edited by Terry Capps; 26th June 2007 at 10:13 AM. Reason: correct attached image URL
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Old 30th June 2007, 09:17 AM   #6
Terry Capps
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Default Re: Extrude along path with Non-Symmetrical surface?

I was mistaken. Apparently, the intersection of the Normal, of a Complex shaped surface, with the surface is not at the Center of the object (Center of Mass). The images in the previous posting were actually made by positioning the beginning of the path at the base of the Normal, and not the center of mass. For the triangle that I used, the position of the Normal and the Center of Mass are the same, but for more complex shapes, they are not the same.

Last edited by Terry Capps; 30th June 2007 at 11:01 AM.
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