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Showing results for tags 'refract'.
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Hey Guys! I've been experimenting with the refract node in vopsop context as well as the refract() function in vex. I'm curious if anyone has been able to break that node down to it's raw form? I would essentially like to know how it actually evaluates it's inputs. Can anyone shed some light on that? I would like to know the math behind it. The refract function takes three inputs, a direction vector, a normalized normal and an index of refraction. thanks!
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Apologies for cross-posting. This is also in Coder's Corner/Shaders--but since this is actually a vopnet... I've developed a stereo lens shader for Arnold, and have replicated its functionality in Houdini--almost. I'm using a grid in front of my ortho camera, transforming P to NDC and driving all of my math from these values. I am using "Refracted Light" VOP in my surface shader to fire rays from an origin that I've computed in a direction that I've computed. All is fine and well when using Ray Tracing--although I was a bit surprised to find that [0,0,0] P ray origin in this context is actually Camera Origin, not Object Origin.(even though it's a surface shader) That's fine--move grid to -0.1 in Z and Camera to zero and all is well. When I started working with PBR, I find that I cannot change the Ray Origin using "Refracted Light." No matter what I do, the ray origin is geometry Surface P. I can get close to the proper results for non stereo if I use a tiny, tiny grid and ortho plane size--but this will never be exact and makes me feel dirty. Furthermore, I need to dramatically alter the ray origin across the image plane for any stereo application of this shader. So--three questions: - How can I exert this control over ray origin in PBR? (direction works fine) - Is there a way to detect the renderer being used from within the shader? (like I said--PBR and RT behave very differently) - Will we ever get the capacity for creating proper lens shaders for Mantra? I'm sure this all stems from a fundamental misunderstanding I have regarding what to do with the BSDF parameter--but not sure how to proceed. Any help is appreciated. Cheers -matt Like This Quote MultiQuote Edit
