A little lesson on Fresnel

This tutorial discusses the Fresnel effect and how it relates to material creation.

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  1. MrBill

    Hey Chris

    I was wondering if the fresnel equation works with transparencies. Im working on modeling A Gatorade bottle with a fruit punch liquid which is not completely transparent but seems to be a bit foggy towards the thickest part of the bottle and more transparent at the thinest part which is around the edges and reflections from the bottom. I’ve tried fog and I’ve tried adding fresnel to my transparent liquid but it seems to gray it out with fresnel and blowing it out with fog. Im also having a problem with an orange transparent bottle cap that is not a uniform transparency on the G2 Gatorade bottle which is basically the same problem.


  2. Chris Tyler

    Yes, it does work with transparency. In fact doing a proper glass material you have to use Fresnel. As reflection goes up, transparency goes down toward the edge. So for a glass you have 0 and 100 for reflectivity. Then you have the opposite values in Opacity. In fact the material dialog has a few ‘helps’ put in place for this. To create glass (which then many transparent material can be based off) set the diffuse/ambient channels to zero. Then, hold the Option key and drag the Reflectivity slider to 100%. This will auto-configure this channel to 0/100 with fresnel (you may want to turn off blurry reflections which also get auto0configured on). Then hold the Option key again and drag the Opacity slider to 0. This will correctly auto-configure the opacity (transparency) channel to produce glass.

  3. MrBill

    I think what was confusing me, I was using layered textures with subsets. The glass fresnel for the main layer which was for the clear neck of the bottle and then an overlapping layer with the diffuse color used for the liquid in the bottle as the subset with inherit. I know through the tutorials I’ve watched you dealt with the combine and multiply. I hadn’t seen any with inherit. Exploring it, it seemed to work for me till I then started adding the fresnel to the opacity on the diffuse layer. I think it must have cancelled out the underlying layer. I’m pretty sure that was my mind set because I was aimlessly tweaking rather than starting over when something didn’t work for me and got myself lost and frustrated. I will try this with the glass fresnel layer since the neck is the thinnest part of the bottle anyway.


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