What I'm really missing is a proper VFB for Karma, currently there is the "viewport preview" and "render to MPlay", both have their uses but it leaves quite a gap in features and UX. (To SideFX: UX means User eXperience, it's a strange concept but bare with me here..
)Obviously I can't speak for everyone's workflow but I think in general creating a render consists of 3 modes:
1) General lookdev, basically tweaking materials, lights etc.
2) Optimizing, trying to keep the same look but in a fraction of the initial rendering time.
3) Solving tech issues. Getting things into the right AOVs or finding ways to avoid steps in comp. Hunting for workarounds and glitches and so on. Basically all non-artistical related things.
For step 1: The viewport is alright, gives instant feedback and gets the jobs done, it's actually quite nice.
For step 2: the viewport doesn't help, hard to tell rending times and hard to compare different setups. In theory MPlay could do this but in reality it just doesn't work for this, or for anything actually tbh. Feedback is minimal and usually there is no clue anything is going on until images pop in there. For this you need al the info possible, from sampling coverage to how it's spending cpu/gpu on each step from scene to pixel to file on disk
For step 3: Quickly toggle features/override shaders etc to find the source/trigger of any issues that might arise. This could involve both bugs in the engine and things like insane light values, 1.0 albedo's etc.
I'm mostly just using the the Karma rop and staying out of the USD stage for now, I'm a one man band and I've really tried, and appreciate what USD is on a technical level, but I'm having a hard time justifying the overhead for what it brings to me. So it could be that the whole experience in the USD stage is much better, so the following is all purely from a /obj level view.
The Karma rop has 3 relevant buttons.. 'Karma Viewport', 'render to disk' and 'Render to MPlay'.
"Karma Viewport": The viewport that pops up and it does the jobs, it feels a bit disjointed and I can't find a way to use the current viewport as a KarmaViewer or set one up manually docked in main ui? Looking at the code behind the buttons I could probably script something but for now it does the job.
Render to disk.. does what it does
"Render to MPlay": Does nothing when pressed or so it seams.. it does quietly start rendering and when it's done it pops up and I don't think it actually renders again until je dump the frame from MPlay or scrub to another frame. Anyways, not useful for doing iterative renders need during step 2 and 3. It's hard to tell rendering progress and it's just pops in when it's finished.. might as well just save it to disk then. Also it's using the 'frame range/current frame' settings. What we need here is a 'production render' vs 'iterative render' workflow, again easy to setup with a few nodes but it's such a basic workflow feature that it should be in there.
And I'd like to see the image evolve/buckets during render, I don't have to wait till the end to judge if something is alright or not. Also simply drawing a rectangle in the render to just render that part or click to focus rendering power on specific area, compare with previous versions, view various stats etc. Also some photometric camera properties could be set by clicking/sampling the viewport. focus distance, white balance, exposure etc. I could write a really long list here but have a good look at VRay and RedShift VFBs they are a very big part of the whole rendering workflow.
I think a good starting point and a big improving would be to have just a simple panel that's like the KarmaSceneViewer but just showing the rendering/rendered rasterized bitmap. By default it should only update with the 'render' button is pressed so it's content isn't as volatile as the viewport preview. Also just render the current frame by default, ignoring any rop settings for this unless told to do so. Then add some non-lookdev features to accommodate step 2 and 3 and take it from there.
