OSL bugs

[stevejjd]

Hi guys,

I just wanted to ask if there were any bugs or limitations in OSL in V-Ray 3.40.01?. I heard there is a problem with bump maps?. I'm just making a library of shader presets and would like to know how reliable OSL is and if there are any known issues or bugs. Also I would like to know if those bugs are fixable?

Thanks.

[Ivan Mavrov]

There are some subtleties, yes.

There are several types of OSL shaders.
We support only the "surface" shader (a material description with a closure output) and the generic "shader" type (a procedural texture description with an RGBA output).

Only the first 24 input parameters can be displayed in the plug-in UI for now.
Not all parameter metadata is supported (like min, max, page, sensitivity) but we have the vital options in my opinion.
Input parameters are not animatable yet.

An OSL texture outputs a chosen output color as RGB and an output float as alpha.
An OSL material output a chosen output closure color.

You can connect OSL plug-ins only via a string input parameter that is interpreted as an RGBA texture in 3ds Max.

I do not know of a bump mapping issue.
As far as I know you need to implement bump mapping yourself in the OSL shader but the language does not provide all the ray differentials V-Ray uses internally so you cannot emulate the V-Ray material bump effect 100%.

You can check out the documentation for more information.