Everything related to Maxwell Render and general stuff that doesn't fit in other categories.
By Laurence Clifford
#397020
Hi,

I'm not sure if this is the correct place for this but feel free to move otherwise.

I'm trying to render up a quick facade detail as per the attached image.
I'm using an hdri background with physical sky illumination and sun on with direction set to cast direct shadows onto the glass.
As you can see the tiled areas are receiving the angled shadows but the glass is not. Based on looking at real life examples there should be some degree of shadow on the glass.
I'm using a slight variation on the P8F Glass with subtle iridescence that has been in the mxm gallery for a long time.

The only way i seem to be able to get it to receive shadows is to increase the material roughness to about 30-50 which then makes the glass frosted.
I tried decreasing the ambient lighting in the hope this would darken the shadows on the glass but this didn't work either.

Is there a way to achieve this? or a trick workaround?

Thanks

Image
#397025
Hi Laurence,

In a perfectly clean glass, the shadow will not happen, as it is a combination of reflection and refraction, but as you say, in reality, you may see a pinch of shadow, probably due to dirt and/or impurity of the materials (sss).
The easiest way to do it in Maxwell is to add a default BSDF next to the glass one lowering its weight to 15 or so. That way you will get a subtle shadow while keeping glass reflectivity properties.

Another trick, as I see you are not getting light behind the glass, is either use AGS (in your case won't look good as the glass pieces are not surrounded by a frame) or hide the glass geometry to GI (global illumination); this will make the glass not cast shadows but will let the light in without any calculation (very fast) and the glass itself will look great.

Cheers!
#397037
thank, sounds like adding a dirt map or glass tint layer at around weight 15 could be the go.
i found that rendering out a shadow channel for the glass material and then compositing in photoshop works too
User avatar
By Forum Moderator
#397039
Laurence Clifford wrote:I found that rendering out a shadow channel for the glass material and then compositing in photoshop works too
Nice trick! The problem with shadow channel is that makes the render quite slower.

Cheers!
Fernando
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