Cycles for Softimage

[Shekn]

Use cycObjectInfo shader node.



The explanation is the following. Even if simple particles simulation used, in the render side it render each particle as instance of one special shape. The mesh of this shape is generated during the render process, but in fact the process is the same as for rendering instances. So, by using cycAttribute you get attributes from this virtual mesh. As it is procedural, it does not contains any special attributes.

[opoppopopp]

...but in fact the process is the same as for rendering instances. So, by using cycAttribute you get attributes from this virtual mesh. As it is procedural, it does not contains any special attributes.

Makes sense

So according to my understand, the ultimate reason for all of these, is because the way blender implement its particles...
Guess blender particle don't have a 'shape', so any "custom shape(even for box)" should use instances.

BUT with that instance route:
it is limited to use 4(r,g,b,a)channel to pass arbitrary PC values, right?
since "Use Pointcloud Attributes for Instances" is in the manual, as a slow fallback, but removed from recent version of Sycles?

[opoppopopp]

And what about that "cycParticleInfo" ?
Seems it is not mentioned in the manual.

• This node gives access to the data of the particle that spawned the object instance.

[Shekn]

Yes, it possible to transfer only four float values from pointcloud attributes to shader tree. And yes, I decide to remove the possibility to render instance shapes as separate objects (and transfer any point cloud attribute to mesh attributes of these objects). The main reason is the difference between Softimage and Cycles render logic. Current behavior is a some compromise (from my point of view). In any case, it's possible to duplicate instance objects as separate objects inside Softimage by using scripting. This approach allows to split this functionality into separate script, and does not implement in the renderer.

As I remember, cycPointInfo does nothing. But may be it's possible to use it in the same way as in Blender. It required more investigations for implementation.

[opoppopopp]

to duplicate instance objects as separate objects inside Softimage by using scripting. This approach allows to split this functionality into separate script, and does not implement in the renderer.

Totally make scene! yes, that function should be split to other script!

As I remember, cycPointInfo does nothing. But may be it's possible to use it in the same way as in Blender. It required more investigations for implementation.

Next, my question is for "cycParticleInfo"(not cycPointinfo), according to Cycles manual(quote below), this is the node intended for instancing (master) objects:

• The Particle Info node can be used in the material node tree for objects that are used as the instancing objects...
• This node gives access to the data of the particle that spawned the object instance...

[FXDude]

Hi!
If I can report some issues I encountered with Sycles 2 ;

- The "Use AO" toggle in "LightPaths" tab of render settings has no effect
( to "disable", set to zero )

- AO in "replace mode" doesn't seem to have an effect / influence
( same render time, and grain pattern as no AO at all, regardless of settings, only "add mode" works )

- Render Region is clamped at 1
( while I think it use to not be clamped ? )

- Background Environment map cannot be visible
( there use to be a render setting to make the background environment visible )

- Portal light toggle does not work, or it hides or disables the light
( enabling Portal Light results in exact same sampling pattern as when it is actually hidden or turned off )

- "reflecti-b-e" typo in Render Option > Light Paths > Caustics

- "Skip rendered frames" does not skip rendered frames.

- Natively SubD-ed meshes does not support Deformation MotionBlur which use to work,
I saw that it was a "known issue", but I would hope that this limitation could be overcome,
as native SubDs are SOO much faster than either the "Subdivide Locally" Op,
or procedural ICE based SubD, which can work as a workaround.

_______________
Otherwise Sycles 2 is a much more complete integration, especially with support of native texture references
( allowing for sources to be relative to project paths, while possibly showing textures in the realtime viewport,
but also working with FXTree processed "fromClip" sources !! which wasn't the case with Redshift )

... as well as support for basic native RT shaders.

In any event, thanks so much & Cheers !

[Botan]

One short question from a person who never used Cycles - why this if we have Redshift 3 (working with RTX 40 etc)?

[Hirazi Blue]

One short question from a person who never used Cycles - why this if we have Redshift 3 (working with RTX 40 etc)?

Answer #1: More options are always welcome...
Answer #2: Cycles is open source (and free)...

Personally I dislike Redshift as they made it impossible to use my permanent license on a whim...🤬

[FXDude]

One short question from a person who never used Cycles - why this if we have Redshift 3 (working with RTX 40 etc)?

a quote from here
https://old.reddit.com/r/Houdini/commen ... lar_among/

glintsCollide 1 point 1 month ago

When RS first came on the scene some 10 years ago they came storming out of the gate with a near perfect integration for Softimage|XSI, it was a very easy adoption and was better at basically everything from the start, leaving Mental Ray in the dust. It was a great move to focus on a really tight integration as a first step, then moving on to the other DCCs, Maya etc, eventually covering most of them. The Houdini integration is no exception, they're doing a great job with it, very dedicated developers for each integration as well as the core engine. This is basically the opposite of what Octane is doing. RS was also the first biased GPU renderer which is also a great move, way ahead of the competition. Summed up, it's a great choice for production.

I think it mostly has to do with "accessibility", if not "legitimacy",
because although there may be some "fixed" 3.0.45 ver. of Redshift around the internets
( last version working with XSI and the latest NV cards ),
some suggested it's no longer possible to "buy" or get a legit version running for XSI,
but you may want to confirm that...

Otherwise, if you still have a working version of Redishift, it's just as awesome as ever !

But Sycles is open-source, so anyone can install it "guilt-free" or otherwise without spending for something you might not be able to install later, while Syscles integration, speed, and other aspects became quite good !

[Shekn]

Some comments to FXDude issues

1-2. About AO settings in LightPath. I don't fully understand how these parameters should works in Blender. And that's why I can not properly implement it in Softimage. In fact I simply transfer parameters from UI to Cycles engine. But may be some additional tweaks are required.
3. What do you mean by "Render Region is clamped at 1"? For output to the screen in render preview Softimage use 8-bit colors. These colors contain channel values from 0 to 255. Or you mean something different?
4. Background is visible if the parameter Film - Transparent is off.

5. The situation with portal light is the same as with AO. I don't understand how it should works.
6. Thank you for the typo in UI
7. Skip rendered frames works for me

[FXDude]

Hi!

Thanks for your feedback/insight, and sorry cause my list was unsorted if not rather "raw"
otherwise, see comments below ;;
____________________________________________________________

1-2. About AO settings in LightPath. I don't fully understand how these parameters should works in Blender. And that's why I can not properly implement it in Softimage. In fact I simply transfer parameters from UI to Cycles engine. But may be some additional tweaks are required.

...

5. The situation with portal light is the same as with AO. I don't understand how it should works.

Indeed ; both AO in replace mode, and portal lights not making a significant difference, seem to also concern Cycles as well.

but the working defaults can also be good,
or not using (therefore not having to set-up/manage) portal lights is also great for simplicity,
( like render anything anywhere )
while still possibly rendering reasonably fast with denoising.


____________________________________________________________

3. What do you mean by "Render Region is clamped at 1"? For output to the screen in render preview Softimage use 8-bit colors. These colors contain channel values from 0 to 255. Or you mean something different?

I mentioned recalling Sycles 1.9 not being clamped, but I may be wrong ? ( haven't reinstalled v1.9 )

But by "clamping" I mean like for MR, Arnold, & Redshift, the render region would be in "high dynamic range"
and pressing CTRL while hovering the mouse over sun reflective highlights for instance, would show values going over 1 (one),

Also, halving the region's "Exposure" setting for instance,
would show highlights originally going over 2, still going over 1 in the display.
( can be important for diagnosis )


____________________________________________________________

4. Background is visible if the parameter Film - Transparent is off.

Indeed! my bad, just overlooked those settings assuming they were for global transparency rays.



____________________________________________________________

6. Thank you for the typo in UI

____________________________________________________________

7. Skip rendered frames works for me

I can confirm that ... sorry, maybe was I confusing different output sequences.



____________________________________________________________
Otherwise, I don't think there was much that I was "missing" or that I "wished for" ...

... except maybe including the pre-denoised output as a channel
( perhaps replacing the "combined" channel which is currently exactly the same as the "main" (denoised) channel ? )


---> in other words, the possibility of including the noisy original combined channel, could be useful in the post-process,
as the "selective re-noising" of denoised images could be using the original noise, thereby recovering yet more details/subtleties.

It seems to be possible in Blender;
From here ; https://artisticrender.com/render-passe ... ete-guide/

The noisy image pass is added automatically if we use denoising. In this case the combined pass will include the denoising data while the noisy image output will be the raw combined output without denoising.

... so perhaps it might also be possible in Sycles ?

____________________________
And ... if I may ask again,
do you think deformed while natively SubD-ed meshes -might- potentially support motion-blur in the future ?
( or pehaps a "hacky" OnRenderStart event script solution ? )

Not just for "blue liquid in classrooms" (lol),
but also for characters or any deforming "organic shapes" in general where motion blur is almost "a must".


In any event, thanks so much for at-all having done & shared all of this, I appreciate the efforts and time,
t'was otherwise fun working with it, and I'm not done yet lol

Cheers!

[FXDude]

including the pre-denoised output as a channel

Hi,
After a few tests, just to say that I think you can scratch or forget that,
because mixing-in the original noise actually exacerbates the inter-frame variance
or results seem better if re-noising using a different noise than the original noise.

Thanks!

[opoppopopp]

For Strands rendering, Is "self.ColorAlongStrands" supported ?
or Cycles do NOT support is Originally?

[Shekn]

I think that Cycles does not support the color variation along strands. But it supports intercept attribute, which measure the proportion of the point along the strand (black at the root and white at the tip). You can use it the shader tree to change the color along strands.

[FXDude]

I think that Cycles does not support the color variation along strands. But it supports intercept attribute, which measure the proportion of the point along the strand (black at the root and white at the tip). You can use it the shader tree to change the color along strands.

Hi!

thanks for the clarification and tips, I will also try that.
it was the same in Redshift, or we could also -not- get per strand segment colors,
but we could use a length gradient
which can be inverted or remapped on the shader side,
rather than on the ICE side.

____________________________________

Also, as I'm finalizing a sample scene with Sycles particles ...
( will post material soon )
... if I can also post an issue ?

Perhaps I was missing something, but is it possible that per-point MotionBlur on particles don't work ?

Motion blur from Camera motion works,
but enabling "Deformation Motion Blur" on the CyclesPointCloud property
despite the "Self.PointVelocity" having velocity information,
only seems to make a horizontal transparency gradient (in camera space) across the entire point cloud.


( BTW, whitewater from top looks like clouds from space lol )

Here is a link to a scene with accompanying 4 frames of cached water particles, if you want to test ...
SyclesParticleMB.zip

Otherwise, rendering particles is GREAT, and VERY FAST to load (or "translate") into Cycles with color, size properties and everything, like not even a second for several MILLIONS of particles !
( it almost doesn't matter how many particles lol )

Thanks and Cheers!

[Shekn]

I made a small test, and it looks like particles motion blur is not working. I will try to understand why it happens. May be the motion blur of native Cycles points is not supported, but may be it's bug in my implementation.