View Full Version : is there an easy mental ray glass?

08 August 2007, 08:08 PM
i've tried lglass and got that to work a little, i think i did the normals wrong.
at first it looked like a giant block of low poly glass i think,
so i just duplicated the model and shrunk it a little
and reversed the normals for the inside hoping it would look thin,
but now its black again.
i just took a scene and deleted the cup, leaving the lights.
which is cheating and why it probably didn't work.
can i give the illusion of glass with just transparency
and spectacular and some sort of ramp?
because i can live with that, but it seems to be turning out plastic looking.
i'm making a dragon filled with stars, and the body is spectral "glass"
i can get it looking pretty cool in maya render with this easy glass i found,
but with no displacements it would look pretty 1980.
i tried searching for a bubble material because that would probably work,
i don't really need caustic lighting on this. it just needs to look glass ish.
thanks for any help!

edit, here's an example of the mental 3 pound crystal ball looking glass,
the maya render glass looks like angel fine fairie dust crisp nice 1/2 ounce glass.
you can see an image plane behind this also,
but its not showing through the mental ray glass at all.
does the image have to be attached to geometry for it to show through the glass?
thanks again!

and here goes the easy maya glass which looks ok,
but i need displacement.

08 August 2007, 10:57 PM

that might be it.

There's a bunch at

The lighting will have big effect on your glass. Spherical environment maps always help getting nice specular reflections and highlights, which I'm not seeing in your renders.

DGS and Dialectric are the go to shaders for glass. There might be some new stuff in 8/8.5 with the architectural shaders, but I'm still using 7.

You're right to stay away from caustics for now.

08 August 2007, 11:41 PM
a) No, you don't need to place your bg image on a card. The camera's back plane is an actual geometry in mental ray (which you place with the Z depth in the image plane editor), so refraction for it *should* work, but maya turns off seen in refractions for it by default. Select imagePlane1 (or whatever) and turn on Visible in Refractions/Reflections for it. Also place it near the sphere with the Depth (Z) setting.

b) You need to have trace refractions and max trace depth to high enough values ( >= 2 ) in your render globals or else the rays will not cross the sphere.

c) Apply a shader with refractions. Best shader these days is mia_material. But if using an old maya, you can use any of the maya phong or blinn native materials. Using the dielectric materials in general is not recommended unless you care to shave off a few secs or so in render time compared to maya shaders (mia_material is faster).

d) Add some transparency and change the index of refraction to > 1. 1.5 is usually glass, which will do the standard physically correct thing of actually flipping around your image when applied on a sphere.

08 August 2007, 12:18 AM
yeah, theres no environment in these, just the light and the image.
thats pretty sneaky with the maya turns off seen in refractions for it by default :)
i almost broke my computer this morning from shaking it with this glass.
shake the evil out!
i just realized i'll have to apply a displacement too.
ugghhh more of the connection editor probably.
(i just spent two hours trying to rig the killeroo
maya nonmental normal render to the cheap easy glass)
i saw a thread about mia mat so i'm sure thats a blast that one!
thanks for the replies, i'll try them out, this glass is really brutal!

08 August 2007, 05:28 PM
Looks like your raytrace settings need to be increased in the mental ray render options.

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