Fresnel Problems, again!



  • I asked before about why my cloth (dynamic single sided) acted almost like a mirror when I could see the "lining" I recieved a good explanation from @bagginsbill as to why that happened. So in that case I just created a second material that would be shown if I could see the lining using the Backfacing output of the geometry node. However I'm now working on a hair shader, and I used the fresnel blend to blend between diffuse and glossy, great. However if you have any of the hair facing the camera from the back, ringlet for instance you get this TIR like effect. Is there any sway, using the backfacing output that I could effectively reverse the normals so this would go away (ISTR this is what the normals forward used to do in firefly shaders.

    Any help gratefully received!



  • Okay I think I've found it via google!

    This is the replacement for the regular fresnel blend for a single sided plane I believe, though I am more than happy to be corrected if it isn't!

    0_1549217927367_268a32a2-6e7c-44bb-84df-2bbc3fb2ace4-image.png


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    Yes this is correct math. There are other ways but this serves without any real flaw, as far as I know.

    This would also correct the architectural glass shader that was recently referenced from blender guru, who himself copied it from elsewhere.



  • @bagginsbill said in Fresnel Problems, again!:

    Yes this is correct math. There are other ways but this serves without any real flaw, as far as I know.

    This would also correct the architectural glass shader that was recently referenced from blender guru, who himself copied it from elsewhere.

    Thanks for the confirmation of the maths, much appreciated, although it didn't work, as usual when trying to recreate cycles materials I got one of the nodes wrong and used a mix closure rather than a colour mix, for some reason using the mix closure resulted in way too much glossy being mixed when compared to the normal fresnel on areas that were all front facing

    0_1549221024710_2b27cdb1-37c3-4a4d-9c1a-02e6ce73c622-image.png