Cycles - Volume rendering fails with Principle Volume Shader, when Film Transparent is on #65993

New Issue

Marcus Papathoma · 2019-06-21T11:54:15+02:00

Marcus Papathoma commented

2019-06-21 11:54:15 +02:00

System Information
Operating system: Windows-10-10.0.17134 64 Bits
Graphics card: GeForce GTX TITAN X/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 430.86

Blender Version
Broken: version: 2.80 (sub 74), branch: master, commit date: 2019-06-19 18:29, hash: d30f72dfd8
Worked: (optional)

Short description of error
Cycles - Volume rendering fails with Principle Volume Shader, when Film Transparent is on

Exact steps for others to reproduce the error

Open the attached blend file.
volume_rendering_fail.blend
Click render Image (F12). Nothing is rendered.
Switch Transparent off, in the render settings.
Render Image again. The volumes are shown but with grey background.
So no compositing of volumes is possible, because they can´t be rendered without the background.
The problem is only with the Principle Volume Shader, if you use the old Volume Scatter shader rendering with transparent background works!
Viewport rendering works, only when you use Render Image or Render Animation the volume isn´t rendered with the principle volume shader and film transparent on.

**System Information** Operating system: Windows-10-10.0.17134 64 Bits Graphics card: GeForce GTX TITAN X/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 430.86 **Blender Version** Broken: version: 2.80 (sub 74), branch: master, commit date: 2019-06-19 18:29, hash: `d30f72dfd8` Worked: (optional) **Short description of error** Cycles - Volume rendering fails with Principle Volume Shader, when Film Transparent is on **Exact steps for others to reproduce the error** Open the attached blend file. [volume_rendering_fail.blend](https://archive.blender.org/developer/F7429601/volume_rendering_fail.blend) Click render Image (F12). Nothing is rendered. Switch Transparent off, in the render settings. Render Image again. The volumes are shown but with grey background. So no compositing of volumes is possible, because they can´t be rendered without the background. The problem is **only with the Principle Volume Shader**, if you use the old Volume Scatter shader rendering with transparent background works! **Viewport rendering works**, only when you use Render Image or Render Animation the volume isn´t rendered with the principle volume shader and film transparent on.

Marcus Papathoma commented

2019-06-21 11:54:15 +02:00

Added subscriber: @machieb

Brecht Van Lommel commented

2019-06-21 11:56:18 +02:00

Closed as duplicate of #65991

Brecht Van Lommel closed this issue

2019-06-21 11:56:18 +02:00

Brecht Van Lommel commented

2019-06-21 11:56:29 +02:00

Added subscriber: @brecht

Brecht Van Lommel commented

2019-06-21 11:56:29 +02:00

Please see the explanation in the other report.

Marcus Papathoma commented

2019-06-21 12:27:40 +02:00

Changed status from 'Duplicate' to: 'Open'

Marcus Papathoma reopened this issue

2019-06-21 12:27:40 +02:00

Marcus Papathoma commented

2019-06-21 12:27:40 +02:00

Have you opend the blend file I attached in this report. The node setup is ok.

With the principle volume shader you can´see anything in the rendering with color and alpha because the alpha is completely black.

If you switch to color in the renderview, you see that the colors are rendered correct. Only the alpha is wrong!

The volume scatter shader works as expected. You get a proper alpha when you render (F12).
{F7430003}
So the principle volume shader can´t be used because when rendering with this shader, its alpha is black and therfore nothing is visible!
So for me this is a bug!
I don´t mind how the alpha is in the viewport.

Have you opend the blend file I attached in this report. The node setup is ok. ![volume_rendering.JPG](https://archive.blender.org/developer/F7429913/volume_rendering.JPG) With the principle volume shader you can´see anything in the rendering with color and alpha because the alpha is completely black. ![volume_rendering3.JPG](https://archive.blender.org/developer/F7430011/volume_rendering3.JPG) If you switch to color in the renderview, you see that the colors are rendered correct. **Only the alpha is wrong!** ![volume_rendering05.JPG](https://archive.blender.org/developer/F7430057/volume_rendering05.JPG) The volume scatter shader works as expected. You get a proper alpha when you render (F12). {[F7430003](https://archive.blender.org/developer/F7430003/volume_rendering2.JPG)}![volume_rendering04.JPG](https://archive.blender.org/developer/F7430038/volume_rendering04.JPG) So the principle volume shader can´t be used because when rendering with this shader, its alpha is black and therfore nothing is visible! **So for me this is a bug!** I don´t mind how the alpha is in the viewport.

Brecht Van Lommel commented

2019-06-21 12:31:47 +02:00

Changed status from 'Open' to: 'Archived'

Brecht Van Lommel closed this issue

2019-06-21 12:31:47 +02:00

Brecht Van Lommel self-assigned this 2019-06-21 12:31:47 +02:00

Brecht Van Lommel commented

2019-06-21 12:31:47 +02:00

For the alpha issue we have #52680 (Alpha difference Viewport/F12 ), as noted in the other report.

If you have only emission and zero density, as in this node setup, then alpha is supposed to be zero.

For the alpha issue we have #52680 (Alpha difference Viewport/F12 ), as noted in the other report. If you have only emission and zero density, as in this node setup, then alpha is supposed to be zero.

Marcus Papathoma commented

2019-06-21 12:38:14 +02:00

Ah ok, thanks, because of the other report #52680: Alpha difference Viewport/F12 the rendering in the viewport locked different, so I had set the density to zero.
Sorry for perturbing you. Thanks for your fast answer!

Ah ok, thanks, because of the other report **#52680: Alpha difference Viewport/F12** the rendering in the viewport locked different, so I had set the density to zero. Sorry for perturbing you. Thanks for your fast answer!

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Cycles - Volume rendering fails with Principle Volume Shader, when Film Transparent is on #65993