cycles stalls with hair particles in viewport #94555

New Issue

Paolo Palmieri · 2022-01-01T17:58:17+01:00

Paolo Palmieri commented

2022-01-01 17:58:17 +01:00

System Information
Operating system: Windows 10 home version 21H1 OSBUILD 19043.1415
Graphics card: no card

Blender Version
Broken: 3.0.0
Worked: prior to 3.0.0

Short description of error

CUBE HAIR packed.blend

cycles stalls in viewport with hair particles, final render does not work

Exact steps for others to reproduce the error

Change the render engine to Cycles
Create the material shown below (The parameter surrounded in red have been modified on the Principled BSDF)
Give the material created above to a mesh object.
On that same mesh object, add a hair particle system.
Enter the rendered viewport. And take note of the slow rendertimes.
"Restart" the render by doing something like one of these steps:

Move, scale, or rotate an object
Click on a material in the 'Material Properties' tab of the Properties editor
Adjust a material property in the world material or the object material
And probably others

Notice the viewport render is now much faster.

Original Steps to reproduce
click display render preview in viewport, observe cycles stalling, then click on 'material' in layout panel, now observe cycles picking up and running at fast pace, then try final render, observe that it does not proceed

**System Information** Operating system: Windows 10 home version 21H1 OSBUILD 19043.1415 Graphics card: no card **Blender Version** Broken: 3.0.0 Worked: prior to 3.0.0 **Short description of error** [CUBE HAIR packed.blend](https://archive.blender.org/developer/F12784410/CUBE_HAIR_packed.blend) cycles stalls in viewport with hair particles, final render does not work **Exact steps for others to reproduce the error** 1. Change the render engine to Cycles 2. Create the material shown below (The parameter surrounded in red have been modified on the Principled BSDF) ![#94555 - Slowed down material.png](https://archive.blender.org/developer/F12784734/T94555_-_Slowed_down_material.png) 3. Give the material created above to a mesh object. 4. On that same mesh object, add a hair particle system. 5. Enter the rendered viewport. And take note of the slow rendertimes. 6. "Restart" the render by doing something like **one** of these steps: - Move, scale, or rotate an object - Click on a material in the 'Material Properties' tab of the `Properties editor` - Adjust a material property in the world material or the object material - And probably others 7. Notice the viewport render is now much faster. > Original Steps to reproduce > click display render preview in viewport, observe cycles stalling, then click on 'material' in layout panel, now observe cycles picking up and running at fast pace, then try final render, observe that it does not proceed

Paolo Palmieri commented

2022-01-01 17:58:17 +01:00

Added subscriber: @PAOLOPALMIERI

Alaska commented

2022-01-01 22:49:16 +01:00

Added subscriber: @Alaska

Alaska commented

2022-01-01 22:49:16 +01:00

Changed status from 'Needs Triage' to: 'Confirmed'

Alaska commented

2022-01-01 22:49:16 +01:00

I observe no stalling with Blender 3.0 or 3.1. Cycles is just rendering slowing.

However, I do notice the Cycles speeding up after clicking on the material in the layout panel. I'll mark this as confirmed.

System Information
Operating system: Linux-5.15.0-2-amd64-x86_64-with-glibc2.33 64 Bits
Graphics card: NA as the file is set to CPU rendering
CPU: Ryzen 9 5950X

Blender Version: 3.1.0 Alpha, branch: master, commit date: 2021-12-31 02:34, hash: 71468f475b

I observe no stalling with Blender 3.0 or 3.1. Cycles is just rendering slowing. However, I do notice the Cycles speeding up after clicking on the material in the layout panel. I'll mark this as confirmed. **System Information** Operating system: Linux-5.15.0-2-amd64-x86_64-with-glibc2.33 64 Bits Graphics card: NA as the file is set to CPU rendering CPU: Ryzen 9 5950X **Blender Version:** 3.1.0 Alpha, branch: master, commit date: 2021-12-31 02:34, hash: `71468f475b`

Alaska commented

2022-01-02 00:34:50 +01:00

Added subscriber: @brecht

Alaska commented

2022-01-02 00:34:50 +01:00

Here are exact steps to recreate the issue from scratch:

Change the render engine to Cycles
Create the material shown below (The parameters surrounded in red have been modified on the Principled BSDF)
Give the material created above to a mesh object.
On that same mesh object, add a hair particle system.
Enter the rendered viewport. And take note of the slow rendertimes.
"Restart" the render by doing something like one of these steps:

Move, scale, or rotate an object
Click on a material in the 'Material Properties' tab of the Properties editor
Adjust a material property in the world material or the object material
And probably others

Notice the viewport render is now much faster.

Taking a look, the issue was caused by fd77a28031 - CC @brecht

Here are exact steps to recreate the issue from scratch: 1. Change the render engine to Cycles 2. Create the material shown below (The parameters surrounded in red have been modified on the Principled BSDF) ![#94555 - Slowed down material.png](https://archive.blender.org/developer/F12784734/T94555_-_Slowed_down_material.png) 3. Give the material created above to a mesh object. 4. On that same mesh object, add a hair particle system. 5. Enter the rendered viewport. And take note of the slow rendertimes. 6. "Restart" the render by doing something like **one** of these steps: - Move, scale, or rotate an object - Click on a material in the 'Material Properties' tab of the `Properties editor` - Adjust a material property in the world material or the object material - And probably others 7. Notice the viewport render is now much faster. Taking a look, the issue was caused by fd77a28031 - CC @brecht

Philipp Oeser removed the

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cycles stalls with hair particles in viewport #94555