I fear I’ve never used sIBL, so don’t know why it doesn’t work, but thanks for the link – it looks pretty interesting and I’ll try it out.

You need mip_rayswitch only if you want to make your objects render black in direct visibility and with shadows in refractions – ‘shadows through glass’ pass, let’s say. For that you need to plug mib_continue into eye and transparency slots of mip_rayswitch, mip_matteshadow into refraction slot and mib_transparency into mip_matteshadow.background (and mip_rayswitch itself into a constant shader that you assign to those objects, surfaceShader for example – outValue into outColor and outValueA into outMatteOpacityR, G and B).

That works through glass made via mia_material shader – I did no tests for other situations.

Excellent and simple solution! Thanks!

I have a question. I’m using sIBL (http://www.hdrlabs.com) and cannot get this to work using that. I’m wondering if it’s related to the mip_rayswitch. Do I need to make a connection using the mip_matteshadow when using mip_rayswitch? If so, where do I plug this in? I’m so confused about this.

Since your shadows are visible through glass, they are actually considered as refraction data. I doubt that automatic pass system would return a correct result right away, so the most reliable way, in my opinion, is to make a special renderLayer with network you want and render it separately – try making your mia_material glass 100% refractive (so it doesn’t appear in alpha) and assign mip_rayswitch to objects behind it. In eye it should be invisible (mib_continue) and in refraction use ‘mib_transparency -> mip_matteshadow’ technique I’ve mentioned. That way in alpha you should get just shadows, refracted through glass.

I hope that helps. Let me know the results, please

P.S. Since you use that transparency trick – you should plug mib_continue into transparency for mip_rayswitch also.

excellent post, thank you! found your site through cgtalk, looking forward to reading more.

quick question – would you know the procedure for getting a shadow pass (from either useBackgroundShader, or mip_matte_shadow) to show up visible in refractions or reflections on a mia_material or a regular maya shader? need to refract shadow pass for compositing, don’t know what to do!

cheers,

m