Improve auto UI generation

[JenusL]

Auto UI generation is made for all native Arnold shaders by the help of a metadata file called arnold_shaders.mtd. Some features would be good do add to that auto generation:

Tabs
Auto UI generation currently lacks the function to create Tabs.
This would come in handy if we want to implement ID AOVs #10

Disabling
The arnold_shaders.mtd has a lot of disable expressions like
soft.disable_when STRING "{ material != custom }"
but there's currently no support for it in the auto generation code.
This should also be implemented.

[caron]

I started to work on this and I am wondering if we agree this is the right place to put it...

soft.order STRING "AddTab My_Tab BeginGroup My_Group param1 param2 EndGroup"

Should look like this...

_________
| My Tab |
__________________________
|   ---My Group---------
|  | param1             |
|  | param2             |
|   --------------------
__________________________

Thoughts?

[JenusL]

I think it looks nice and clean.
Just one question… Is the AddTab required for the default first tab or only for extra tabs?
I would prefer if it was only for extra tabs.

[caron]

So if you do this...

[node mynode]
soft.order STRING "param1 param2 AddTab My_Tab param3 param4"

You will get a first tab named 'mynode' with param1 and param2 on it. Then a second tab named 'My Tab' with param3 and param4 on it. This is just Softimage PPG's default behavior I believe. Nothing in the SItoA code is deciding this.

[caron]

So I wanted to brainstorm about implementing this parameter disabling PPGLogic in mtd files. So I think we have to use the PutLogic method of the PPGLayout class...

PPGLayout::PutLogic

@sjannuz you defined some logic in the metadata file already for this. It exists on the parameter/attr... what was your initial design? Using PutLogic with a scripting language? Or some other dynamic way in C++? Right now since the PPGLogic exists on the entire PPGLayout and not on individual parameters I would need to collect all the soft.disable_when metadatas when params are defined and then build the script logic somewhere before or during the Layout function where it gets "put".

[sjannuz]

Hi Steven. The metadata file contains more than what SItoA handles, simply because it was common to the other plugins (HtoA was the first fetching the logic from the mtd). Then I did not have the time to include it in SItoA, nor any exact plan about how to handle it in the code.

[JenusL]

@caron Could you create a PR with the just the tab-stuff and we save the disabling for later?

[caron]

I can once I return from vacationing next week.

[caron]

@sjannuz Thanks for the feedback. I want to be sure .mtd file made for SItoA works with other plugins and vice-versa. Is there any .mtd files from other plugins I can use to test?

[JenusL]

I think the .mtd files are pretty different across the different plugins but I guess you could try.
The maya one can be found here: https://trac.solidangle.com/mtoa/browser/mtoa/plugins/mtoa/mtoa.mtd
That's the one I take min/max softmin/softmax from when I've added new shaders to SItoA.

[caron]

Thanks, @JenusL but I don't see any disable_when examples. But looking closer now the soft. prefix will make it specific to SItoA and I won't need to worry about supporting another one.

[JenusL]

Yeah the soft. prefix will make it safe so use that.

[JenusL]

I just want to say, for traceability sake, that I extended the auto UI generation by adding support for soft.node_type in #26

[caron]

I will make sure to work on top of #26 when supporting 'disabling metadata'.