playing with idea to use the dot product of incoming ray and surface normal to generate superfast fake caustic’s
here are some tests:
Arnold Caustics shader
Designer , Effects lookdev, Artist, Technical Director
Designer , Effects lookdev, Artist, Technical Director
playing with idea to use the dot product of incoming ray and surface normal to generate superfast fake caustic’s
here are some tests:
Heri 
Which rays are you dot’ing? The incident ray from camera to the crystal surface? Maybe you could give a bit more explanation please? I’d like to test creating this in houdini.
sorry for the delay, the the cross product from incoming ray and surface normal, –> pipeline into a ramp and then into shadow plug of ray switch shader.
I was inspired by this tutorial, https://www.youtube.com/watch?v=1p7l9MNpLdo&t=1612s
when I computer is running again I can post a hip file.
Hello Heri,
very interesting tricks, thanks for sharing !
I tried to reproduce it on arnold by folowing the blender cycle tutorial, but I’m stuck on one step.
In the blender tutorial, the transmission is set to a value above 1, wich increase the intensity of the light ray traveling through the glass, making the caustic effect more visible.
In arnold, I think the transmission clamp any value above 1 as not to break the energy conservation.
So I have the rigth caustic pattern, but they are pretty weak.
In your examples it look like you tackle this issue.
Any tips to share =D ?
you can increase the shadow density on the light parameters. but most of the time I just rendered a “shadow” pass and add it on top in comp.
Thanks Heri for the quick reply !
I think increase the shadow density was possible on previous arnold version, but on Arnold 7 it is locked and there is the warning below: “Cannot set the attribute ‘aiAreaLightShape1.aiShadowDensity’ past its maximum value of 1.”
I’m going to have a better look at the shadow pass.