Render brightness information into alpha

Unity Engine
1

Hi Guys,

currently I’m playing around a lot with custom built shaders, most of which are stolen from Nvidia and AMD examples.

A lot of those examples require the brightness information of the environment map to be in the alpha channel of the texture to emulate high dynamic range.
From my experience with the gamebryo engine you needed to built every single shader from scratch, or apply a post filter to an HDR-texturebuffer (which wouldn’t work on ps2.0).

So my question is: Is it possible to do this, with standard UnityPro shaders, or do I need to build them all by myself (which I tend to do anyway)?

By the way. I can adjust the dynamic range for bitmap textures but not for render textures. Is it possible to render to a HDR buffer (16 or 32bits/channel)?
Would be highly appreciated for the RenderToCubemap() function.

2

What do you want to render to the alpha channel? The built-in Diffuse shader, for instance, renders alpha in much the same way as it renders RGB, except that ambient light is not factored in. If you want alpha treated differently, you’ll have to use your own shaders, of course.

Floating point textures are not yet supported by Unity.