Hi everybody! I have some OSL shaders lined up for you which I’ll post here one by one as soon as the page for the shader is done. To kick this off I present to you… The Reflector! Links Page: OSL – Reflector – Rens Heeren Download: http://www.rensheeren.…

Hey Rens, I have a request for ya. You have several Fresnel implementations, each based I believe on viewing angle. It would be great if you could write an OSL Fresnel calculated per microfacet, rather than viewing angle, as described here (page 10-12). As you can see in the images, this is importa…

[image] Car Flakes as map I have a request for ya. You have several Fresnel implementations, each based I believe on viewing angle. It would be great if you could write an OSL Fresnel calculated per microfacet, rather than viewing angle, as described here This is not possible in OSL; it must b…

[image] Vray 3 Maya Proxy Subdivision Problem This is not possible in OSL; it must be supported in the BRDFs provided by the renderer. This will be implemented in the next SP of V-Ray Vlado Thanks for the explanation. Some followup questions: 1) The only OSL brdf that has Fresnel currently i…

[image] Motion Blur Sets 1) The only OSL brdf that has Fresnel currently is the microfacet_ggx (the eta parameter). Is it correct that this currently is not using per microfacet Fresnel, but will in the next SP? This is correct, yes. 2) Will a Fresnel term that uses per microfacet be added t…

[image] Vray 3 Maya Proxy Subdivision Problem OSL has no way for closures to return this transparency so it must be computed in another way, potentially duplicating the work done by the BRDF. You could do the energy preservation but you’ll have to duplicate the Fresnel work done inside the clo…

[image] Elder Scrolls Trailer from Blur You do the Fresnel term math (hopefully matching that of the microfacet_ggx) and figure out the reflection weight. Right. The burning question then is: What would the code be for that?

You can probably trust the built-in “fresnel” function. surface FresnelWeightedSurface ( color diffuse_color = color(1.0), color reflection_color = color(1.0), float environment_ior = 1.0, float material_ior = 1.5 ) { float environmentIOR = max(1.0, environment_ior); float materialIOR = m…

Okay so you are using the built in OSL Fresnel standard library function. That makes sense. I guess the question then is this: If in the next SP the microfacet_ggx will be updated to use per microfacet Fresnel, will the OSL fresnel function also be updated to calculate based on each microfacet of a…

You got me there. No, it cannot be updated. It is part of the OSL 1.3.3 standard and even if we edit it - the microfacet normals used for sampling will be on the renderer side of the wall and totally unreachable by the OSL code. We’ll have to figure something else.

Yeah. I think if we just used the per viewing angle Fresnel to attenuate the diffuse, we would end up with yucky darkening on the edges (an error that comes up a lot with sss), which is one of the issues that per microfacet Fresnel solves. I asked again in the OSL developers group. Hopefully someo…

An assortment of OSL shaders for your perusal

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sharktacos August 31, 2016, 1:50pm 121

Right. The burning question then is: What would the code be for that?

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An assortment of OSL shaders for your perusal

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