Your input needed: Background overrides

[Javadevil]

I suggested the shader background environment switcher, similar to mental rays.
It's handy to have a material library setup with combinations of hdri environment maps, back ground maps, (reflection and refraction if need be).
Scenes that require multiply lighting configurations are easy to setup this way, one shader for dusk, one for day light, etc..   
Simple drag and drop a prepared environment shader into the background, its easy to transfer shaders around to other people in the office without needing the a 3dsmax scene.

I'd like direct lighting over ride for Glass materials, that have attenuation, instead of physically based caustics.

Tone mapping needs a "Do Not" effect background map.

Scene material override, have an option for material Buffer ID overrides, Instead of object based, this works better for multi-sub material objects.

[Ondra]

ok, look like we have consensus on the first two questions, I've added vote on the last one

[Paul Jones]

Remove all main background settings from Corona dialogue, use 3dsmax's entirely

This!

Second problem: What should be overridable on per-material basis? Only reflections? Reflections&refractions? Direct rays (what is seen through transparent materials)? What is seen on diffuse surfaces?

finalRender can override per material all reflections, refractions and GI, but I've personally never used the GI override, to be honest. So my vote would go to only Reflect/Refract overrides per material.

And the last problem is how to implement the per-material overrides in GUI. One possibility is to add map slots for all of them. Other possibility is to create a special Corona map that will have the different slots for different overrides. This was proposed by somebody (I dont remember who) as easy way to intechange prepared "presets" of backgrounds.

See attachment.

Third problem: Implement individual overrides or "override shader" texmap? Which is more user-friendly? Do the override shader also for global overrides?

Don't mimic mental ray. :) Use direct overrides, not specific shaders. ;)

Pretty much nailed it there Loocas

[superrune]

Choices are good I think. In Brazil you could do both environment overrides inside the material and through the renderer. I would support overrides of both reflections and refractions inside the material if I were you. I've sometimes missed the MR override texture as well, that seemed like a neat thing.

I recommend doing a comprehensive override material, such as Brazil used to have (see screenshot). For some, this might seem as overkill - but it's extremely flexible in use. Using the Slate editor, it's very easy to take a complex car material, and then make multiple variations on it by overriding just the color or the bump. You can also substitute the GI rays for that material with a simpler material (say without bump, sss or reflections) to speed up render.