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General Category => General Anim8or Forum => Topic started by: Ralf1324 on January 16, 2008, 10:22:25 pm

Title: Fresnel Lens
Post by: Ralf1324 on January 16, 2008, 10:22:25 pm
Hey, all. I am currently making a model of a theatrical light called A Fresnel lantern. I have completed everything but the lens. I can't figure out how to make the lens look like a Fresnel lens (http://spie.org/Images/Graphics/Newsroom/Imported/333_1628_0_2006-08-05/333_fig1.jpg) Look at the image all the way to the right. That is a side view of what the Fresnel lens should look like. Any ideas?
Title: Re: Fresnel Lens
Post by: Kubajzz on January 16, 2008, 10:32:10 pm
I'm not really sure if I understand what you want to do, but I would try lathing...

Just draw a spline in the shape you need and click Build>Lathe...
Title: Re: Fresnel Lens
Post by: Kubajzz on January 16, 2008, 10:47:46 pm
Ok, it seems we have a different problem... Meshes and splines are something very different and it's not possible to use "Convert to mesh" and "Convert to spline" tool. I guess you used some mesh, deleted most of it's points so you had only a few edges left and tried to lathe this; it doesn't work because what you have is still a mesh and it's not possible to cenvert it to spline.
Here it goes step by step what you should do:

1. You must select the "Curved path" tool in Object mode and draw the spline; look at this part of the manual (http://www.anim8or.com/manual/3_object_editor.html#splines) - it gives a full explanation on how to make/edit splines

2. When drawing the spline, remember that the new mesh will be created by rotating the spline around one axis; therefore some points of the spline should be placed directly on the axis. Click here to display "Lathing" chapter in the manual (http://www.anim8or.com/manual/3_object_editor.html#lathing)

Hope this helps... Good luck
Title: Re: Fresnel Lens
Post by: Ralf1324 on January 16, 2008, 10:48:52 pm
I drew a spline and lathed it, but that didn't work.. (http://www.starmgc.com/images/fresnel.jpg) A better representation of the lens.
Title: Re: Fresnel Lens
Post by: Ralf1324 on January 16, 2008, 10:50:55 pm
Yeah..I figured out the meshes couldn't be converted after I tried it lol ^_^...But my problem is making the shape..I will try different things and post again later..look at my previous post for a better example of the actual lens.
Title: Re: Fresnel Lens
Post by: Kubajzz on January 16, 2008, 10:54:01 pm
If you managed to draw and lathe the spline, it probably means that the only problem you have are wrong setings of the spline/lathing options
The only thing I can recommend you is to read the manual carefully... And then keep trying all different shapes and settings until you get what you need. Good luck!
Title: Re: Fresnel Lens
Post by: RudySchneider on January 16, 2008, 11:35:51 pm
Here's a quick Fresnel lense object I threw together for you, along with the original curve from which I lathed it.  I simply put your reference image in the background and traced over the top half.
Title: Re: Fresnel Lens
Post by: Ralf1324 on January 16, 2008, 11:43:04 pm
PERFECT! *HUG* THANK YOU SO MUCH! Can you just explain again how you did it? I understand the reference image thing, but how did you lathe it...oh wait! I GET IT! THANKS!!!!!!!!!!!!!!!!!!!!!!!