Cycles Requests

It is already using cuOccupancyMaxPotentialBlockSize() and scheduling several samples at a time if a single sample per tile isn’t saturating the GPU. See device_cuda_impl.cpp, CUDADevice::render().

Assuming you have enough samples.
E.g., If you are doing a progressive render, that won’t help.

Could this improve Cycles caustics and denoising speed?


I didn’t notice there was this Cycles Requests thread.
I’m going to throw my request in here.

Can we add a boolean at render time?
Similar to what in other render engines is called Clip Geo or Clipper.
Basically, the boolean is handled via shader.
Examples in this thread


That would be neat!
Setting up such effects with booleans is tedious (clipping away many objects requires a modifier for each object) and error prone (booleans on non-closed or non-manifold meshes).

1 Like

May I point your attention to this thread (How useful could be a Material Input node?) to discuss the idea?

1 Like

To improve Cycles realism I’d also love to see proper micro-roughness added.

Have a look at this interesting Blender Artists thread for more info:

1 Like

Are you sure Cycles does not have that already?

As far as I know Cycles doesn’t have this yet, but I’d be happy if I’m incorrect. :slightly_smiling_face:

You might be interested in trying this addon:


37 posts were split to a new topic: GPL license discussion

I guess this discussion about licensing must have come up before on
Please keep the thread on-topic. Create a new one to discuss this, and link that here.

1 Like

couple of points there

  1. That was my personal opinion, this is in no way / shape / form the stance of the blender project as a whole
  2. Always lovely when people post a private conversation without asking, while you are naturally free to do so, it is very likely I will be much less engaging in future conversations with you.

I’ve split the GPL license discussion to a separate thread.

Feel free to continue the discussion there, as long as you keep it respectful. Thanks.


Well, in forums more and more users are wondering how it would be possible to speed up OptiX denoiser’s work in transparent areas.
Adaptive Sampling solved the problem for render in transparent areas. Could it be possible that somehow OptiX denoiser could do something similar to what Adaptive Sampling does in transparent tiles to speed up the work?

1 Like

Is performance overhead of the OptiX denoiser a significant issue? It has not seemed to be for me. Is it slower on cards that do not have tensor cores?

Also, I believe the OptiX denoiser is essentially a black box in the graphics driver the Cycles hands image sections to and gets back denoised versions, so not sure there’s much the Blender/Cycles devs could do. (except maybe identify empty tiles and skip denoising them entirely?)

So, as for my Cycles Clip Geo node suggestion it seems even Octane is adding it in the next release 2021:

OTOY • OctaneRender 2021™ Preview is here!

I still think this is a neat feature and it will be hopefully added at some point :slight_smile:


Raytracing-based Bools would be cool indeed.
In the meantime I was partially successful accomplishing something like this with a shader. Plenty of breaking instances so it’s far from perfect, but for the simplest cases it might work for you:


Probably I’m too lazy to figure out for myself: what are the conveniences over the regular boolean modifier? Or I should say, a node-modifiers enpowered boolean operation?


The advantages of Booleans at rendertime that I can think of are:

  1. Your scene is not bogged down by Boolean modifier operations being (re)calculated.

  2. Very complex high-polygon Booleans might be enabled by this.