Cycles render viewport can't get past first sample

Hi there,

Not quite ‘rendering’, but Render Viewport.

I switch my viewport to render view and it can’t get past the first sample, which means it keeps trying to again. This results in a stuttering image. I have switched between CPU and GPU, same thing.

It only does it when some objects are visible. when these objects are hidden, the other objects render in viewport fine.


check your sample setting. this is the highest blender will render it to. for viewport, set it high enough for you to be able to read the image properly, and for Render, set it as high as needed to get a clean look without grain.

btw im pointing at Clamp settings, dont touch those… im refering to Samples.

I’m afraid that is not it. No matter what the viewport Preview sampling is set to, it still stutters. I have viewport sampling set to 32, and you can see the Path Tracing Sample number rapidly trying to forever climb to 32, but it never gets past 7 or 8 samples, and starts back at 1. This happens so fast that the image looks like its flickering.

I have noticed only certain materials do this. If a cube with such a material is visible, the flicker will happen. If you then change the material of that cube to another material, it samples up to 32 just fine.

What’s even stranger, is that if I import that material into a new Blender file, it will work fine.

In the original file where the problem happens, if I set Path Tacing Sample to 1, the flicker still happens. It seems like it is forever aborting the sampling, a bit like when you try to render viewport while running an animation, it will forever start resampling every time a change happens, except here, the timeline is static.

UPDATE:
It seems that when a material has a Texture Coordinate node set to ‘Object’ and then an object is selected in the dropdown menu of said node, it causes the above. The moment I remove selected object from the Texture Coordinate node’s ‘Object:’ dropdown the flickering stops.

Is this a bug?

i am unable to replicate the problem. provide a detailed step by step guide on how to set it up, or provide the blend file