Hello guys !

I have a problem with Mantra, when I'm rendering a simple mantra surface shader with Reflections On and Refractions On and Fresnel Blending Ticked, my refraction is black near objects.

If I unticked Fresnel BLending, it works. So what I need to know and do to solve my problem.

Thank you very much if you can help me.

Reflection + Refraction :



Refraction Only :

That's because Houdini doesn't render shadows for refraction, Transparent Shadows option in the light setting only work for opacity , Not refraction !
So you have two solution :
1. Add causticlight for generating caustic.
2. Use Fake caustic option , to use this option go to mantrasurface parameters –>Opacity–>turn on Enable Faux Caustics

Thank you so much Rabiee for your quick and perfect reply.

I don't know why it doesn't work with the causticlight, but it works perfectly with “Enable Faux Caustic”

PS : Do you have an idead about how can I avoid the little “noise” of my sphere on my render ? (you can see it on the first picture) My : Mantra Sample is set to 8 x 8

But Caustic Light working perfectly on your project :!:
Just add Caustic Light from shelf tools and tab Render !!!

About your second question , You should just increase Sampling Quality parameter in the envlight settings.

Increasing pixel sample is very slow in rendering :wink:

This is your project with Caustic Light and without noise :wink:
Of course using Caustic Light is so slow in rendering .

Thank you for the file and the tips about increasing Sampling Quality parameter in the envlight settings.

It's Crazy. When I launch you file, the Caustic Light works like a charm. If I delete it, and create antoher one with the shelf tool, it works fine.

Therefore, in my original file, if I create a Caustic Light like above, anything change. It doesn't work.

Did you change something else to integrate perfectly the Caustic Light ?

Have good day

No , I just add a caustic light from shelf without any special setting !
Test it in the another project , Also use another Mantra node with default settings , Maybe you changed some special parameter in the Mantra node :?

I have deleted my Mantra PBR, re create a new one with same parameters and now it's good :shock:

Thank you for everything !

Hate de voir ce que tu nous prepares

Salut Tom je bosse sur un projet perso de rapide/whitewater que je posterais dans pas trop longtemps j'espère

Ah énorme !
Je suis aussi sur une scène du genre actuellement mais bon j'ai moyen le temps Au fait tu seras à la soirée “graphix” (si c'est bien le nom) le 18 ?