mayaToCorona 0.41

[haggi]

Small updates:

release 0.41
- fixed a problem with esc key which caused a premature stop of the next rendering.
- fixed set shading override if no shader is connected
- added bump map attribute to corona surface shader #142
- reimplemented batch rendering
- added highly experimental CoronaVFB

You can turn on the CoronaVFB in render globals under features, but it is really experimental and most features do not work yet. So it may be unstable with the CoronaVFB.
Batch rendering works again. Commandline rendering is not tested and is supposed not to work yet. This will be fixed in the next release.

[RickToxik]

Hi Haggi,

  thank you for letting me join the beta.  My first impression are that I am very pleased with Maya to Corona, it looks really stable, very responsive, well-featured and nicely integrated into maya for a beta.  I do miss all the utility nodes of maya but I guess some of them will come along the way some day.

  I have noted all the little things that were not behaving as expected - or some ideas - but it's really nothing...  I was able to complete a first scene as I would with any other renderer.  I only had one crash but I don't think it's related to Corona.  When I started from a new scene it has been 100% stable.

So, my notes are:

- IPR not working

- frame buffer crashes

- absorption / sss values changes do not appear in shader swatch

- It would be nice to link attribute of the sun intensity in the render settings (along with the sky multiplier) instead of going in shape tab

- For the fresnel map of the corona surface, it would be AWESOME to add a falloff map like in 3DS max, maya users have wished that for a long time.  Would it not be possible to hack a ramp from the Remap Value node of maya and control fresnel ramp with that?  I did not find any info on this fresnel map attribute, not sure how to use it.

- maybe add a multiplier for file environment, when you use an exr to hdri you scene.  I did not know how to light properly with those, the luminosity was too dark and could not fix it...

- ctrl-leftClick-slide in the render settings do not step correctly for some values, maybe lower the step (highlight compression, contrast)

- contrast does not go below 1.000

- Autosave crashed once...  I will look further into that - I was not able never to repoen my .ma (I started from an old scene though)

- no support for hdr, from what I understood in the forums?

- corona surface does not appear in my right-click menu favorite materials, even though it's added as a favorite material

- There is no turbidity for Hosek and Rawafake, how do you add atmospheric dirt for those two...  without a volumetric solution...?

- Could we have an option in maya for converting to tx?  Arnold does it and even replaces a jpg with the tx version at render time - so you can still view your textures in viewport 2.0 and render with mipmapped.


Finally, some questions:

1. Are the Corona surface shaders energy-conservative?  They looked blown-out with high diffuse and reflection in my hypershade?

2. I know that you cannot support maya nodes, but it would be very useful to have something like the layered texture, I use it all the time...  I know that there is a corona layered shader.  Having an ambient occlusion texture and dirt texture would be cool too.  AO is a must I think : )

3.  You mentionned in the first email you have sent me that there was a "pdf" (for maya to corona?).  Can you link me to it, maybe a sticky thread for that would be useful, even if it's not updated at each version of the beta.  It was supposed to indicate which maya nodes were supported.  Any generic info on

THANK YOU!  I love my new toy : )  I was really surprised how stable and responsive the plugin was.  Congrats!

[haggi]

Thanks for the detailed feedback.

• Can you tell me which utility nodes you miss most?
• Indeed, IPR is not yet supported.
• With framebuffer, you mean the highly experimental corona framebuffer?
• Concerning falloff map. How does it work in 3dsmax?
• Hdr is not supported if you connect it directly to the environment color. It is supported for any other normal texture mapping including mapping for a CoronaLight.
• Only preetham supports turbidity, that's how it is defined in the API.
• Converting to tx will come in a menu or other place. Until then please have a look at the release notes for mayaToCorona 0.38 here in the forum.
• Corona materials are energy conserving.
• I will create a layered texture node. Corona layered shader is not really supported. The way it works is a bit complicated to implement at the moment.
• In the archive mayaToCorona_0.41.zip is a directory called docs and it contains... well you guess it: The pdf ;) .

[RickToxik]

Hi Haggi!

- Personally, I mostly use the Remap Value (for Alpha), Remap HSV (for RGB) and Gamma utility nodes.  If you have to recreate from scratch you could build a custom color correction node specific to corona, but imho I think it's better to stick to maya's philosophy / nodes: that way, the renderer can play well with mel and python scripts floating around as it keeps the same input and output names, attributes, etc....

- Yeah the framebuffer I meant the highly experimental lol..  It crashed maya 2015 as soon as I was launching a render view

- I will read the docs and look around concerning the fresnel map, as I don't know how to use it right now.  In 3ds Max, people use mostly the falloff map to control the amount of reflection at 0 and 90 degree with a curve.  The idea is to have more control than a linear curve.  In 3ds max it can be set to control other things than parallel / perpendicular reflections, but I believe that's the main usage.
http://knowledge.autodesk.com/support/3ds-max/learn-explore/caas/CloudHelp/cloudhelp/2015/ENU/3DSMax/files/GUID-B3F75800-E884-467B-A4D1-C95702BFA15F-htm.html
The ability to control fresnel with a map is very cool it would be nice to be able to control the amount of fresnel with a curve (there are curves and ramps in many nodes in maya) - just an idea coming from 3ds max : )

- For the layered texture, yeah it would be totally awesome to have it if possible!!

edit: After reading the docs, I did not know corona maya already supported some utility nodes, I will use those already supported!

[haggi]

Even if the pdf is not up to date, you can have a look at a file called "shaderDefinitions.txt" in the resources subdirectory of mayaToCorona. All nodes which are mentioned there shoud be supported, at least partially. Additionally, if you want to see if a feature is already on the toDoList, you can have a look at the issues list on github: https://github.com/haggi/OpenMaya/milestones/mayaToCorona

Could you please check your normal maya workflow for shading and check if the falloff map works? In Maya you normally connect the facingRatio of a samplerInfo node to the vCoord of a ramp node and this is then plugged into any attribute. Both should be supported in mayaToCorona. You only have to delete the placeTexture2d node of the ramp node. The color remap workflow should work as well, all necessary nodes are supported.

[RickToxik]

Hi!

  yes the sampler info => ramp => fresnel map works as expected, exactly as a falloff map would do in 3Ds max indeed.  Being a bit of a lazy node connecter, I admit I would not use that setup all the time or I would script it because of the complex setup to build for it  It works good though and does what it's expected to do.

[RickToxik]

Hi!

  I was wondering how do I rotate my EXR environment for IBL?  I thought I was able to do it before but no, it seems that the place2D node attached to the environment file does not have any effect.

  Also, in the case that it would be possible to rotate it: since we do not have IPR or the Corona frame buffer yet, it could be cool to have a visual feedback of the dome in the viewport as an option.  Will the Corona Frame buffer provide realtime feedback for lighting?

Thanks!!

[haggi]

At the moment only simple texture files are recognized by mayaToCorona. There are some restrictions concerning the implementation of environment maps, but I'll try again with the new API.
A visual feedback is definitly planned, but it has low priority.

[RickToxik]

Cool!!  Thanks, keep up the good work : )

What's already in MayatoCorona is really stable.

[RickToxik]

Hi Haggi,

  I would have an archviz project for a client that would be perfect for testing Maya to Corona: no deadline, awesome model, interior exterior with glass and several rooms, etc.

  I am very nervous though about not being able to rotate my hdr / environment, I fear that my client would ask for lighting changes late in the process and I have multiple lighting conditions to render...  Is there any workaround that I could use, like lighting with an emissive dome? Would it mess with any importance sampling process?

  It would be very cool to do this project with Corona, I am waiting for your ideas : )

[Hamburger]

Unfortunately Sun + Sky does not work also as it produces inaccurate result and incorrect shadows, so your choices for lighting changes are limited at this early stage.

What you could do is group the entire scene (cameras too) and rotate the scene instead. It's the only workflow for now but does HDRI even work? Last build it did not work as of yet.

[RickToxik]

Hi Hamburger!

Yeah the built in hdri works pretty good (no .hdr though), it renders quite fast.  Like I thought, lighting with a sphere with a hdr texture does not produce the same results as lighting with the environment, it's a lot more noisy.

I did not know the sun and sky were not accurate though, i had good results when I played around with them...

Yes the scene rotation is definitly the only way to go I guess currently! 

[RickToxik]

Hi,

  I might not be plugging things properly, but I cannot plug the alpha channel of my file (tif, exr, png...) into the opacity slot of the corona surface.  It works with other renderers / shaders, but the same alpha channel is not properly read by corona.  It renders like semi transparent, full on or full off.

  Like I said, it might be an error on my side.

[haggi]

Unfortunately Sun + Sky does not work also as it produces inaccurate result and incorrect shadows, so your choices for lighting changes are limited at this early stage.
What you could do is group the entire scene (cameras too) and rotate the scene instead. It's the only workflow for now but does HDRI even work? Last build it did not work as of yet.

The physical sky is much better in the next release. Still working on a hopefully simple problem, but as soon as it is fixed you can control the HDR with colorBalance in the file node and uv manipulation.

[Hamburger]

Thanks for the news Haggi!