GafferArnold : Light filter node float plugs are unclamped

[medubelko]

Version: Gaffer 53.1.0.0 Third-party tools: Arnold Third-party modules: None

Description

Not sure whether to file this under bug or oversight, but @mattigruener suggested I bring it up. In our node implementation of the Arnold light filters, we don't clamp the following float plug values:

• Barndoor shader: All flaps can be set outside 0-1. I can't think of any reason for opening up a flap to a negative angle, but maybe there are legitimate uses for flaps greater than 45°?
• Gobo shader: Density can be set outside 0-1. Again, are there any legitimate uses for doing so?
• Decay shader: All the attenuation boundaries can be set outside of 0-1.

Maya's implementation clamps these.

Arnold may accept any float value, but it's probably worth it to prevent the user from inputting non-meaningful inputs. I'm not sure how this fits into our other practices with float clamping. Do we have any kind of standard in place?

[johnhaddon]

For Gaffer's native nodes, generally we have hard min/max values to prevent any plugs from being given values that are invalid for their particular use.

So I think we should :

• Add min/max metadata as appropriate in gaffer.mtd. It's a pity they don't just ship a sensible metadata file with Arnold, because I think we'll basically just be reproducing the same limits that they specify in the metadata file for their Maya plugin.
• Support that metadata in src/IECoreArnold/ParameterHandler.cpp, mapping it to min/max limits on the plugs created.