Texture with alpha renders differently in Eevee and Cycles #76712

New Issue

Zsolt Stefan · 2020-05-13T09:34:41+02:00

Zsolt Stefan commented

2020-05-13 09:34:41 +02:00

System Information
Operating system: Windows-10-10.0.18362-SP0 64 Bits
Graphics card: GeForce RTX 2080 with Max-Q Design/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 442.19

Blender Version
Broken: version: 2.90 (sub 0), branch: master, commit date: 2020-05-01 21:55, hash: 83304e4c22
Worked: (newest version of Blender that worked as expected)

Short description of error
I have a PNG texture with an alpha channel, plugged into the FAC input of a mix node. To switch between two shaders and show a pattern on the object surface.
In Eevee, the alpha map is used, and the texture appears on the surface. The cycles rendering is different, the pattern is not shown.
I don't know which one is the intended behaviour, but in any case eevee and cycles shouldn't render differently.

Related bug: there is a node attached to the alpha output of the texture, it is however not used for anything right now. If I however delete it, unconnect and reconnect the nodes, then eevee also stops using the alpha channel.
An unused node should have no effect on the output.

Exact steps for others to reproduce the error

Open the attached BLEND.
Switch to Material Preview. The surface has a pattern on it.
Switch to Cycles. The surface has no pattern.
Switch back to Material Preview. Delete or unconnect the unused "Invert" node in the Shader Editor.
Nothing happens.
Unconnect the Texture Colour Output connection to the Fac Input of the Mix Shader node.
Reconnect the same connection.
Now the pattern has disappeared.

Texture_with_alpha_renders_differently_bug.blend

**System Information** Operating system: Windows-10-10.0.18362-SP0 64 Bits Graphics card: GeForce RTX 2080 with Max-Q Design/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 442.19 **Blender Version** Broken: version: 2.90 (sub 0), branch: master, commit date: 2020-05-01 21:55, hash: `83304e4c22` Worked: (newest version of Blender that worked as expected) **Short description of error** I have a PNG texture with an alpha channel, plugged into the FAC input of a mix node. To switch between two shaders and show a pattern on the object surface. In Eevee, the alpha map is used, and the texture appears on the surface. The cycles rendering is different, the pattern is not shown. I don't know which one is the intended behaviour, but in any case eevee and cycles shouldn't render differently. Related bug: there is a node attached to the alpha output of the texture, it is however not used for anything right now. If I however delete it, unconnect and reconnect the nodes, then eevee also stops using the alpha channel. An unused node should have no effect on the output. **Exact steps for others to reproduce the error** - Open the attached BLEND. - Switch to Material Preview. The surface has a pattern on it. - Switch to Cycles. The surface has no pattern. - Switch back to Material Preview. Delete or unconnect the unused "Invert" node in the Shader Editor. - Nothing happens. - Unconnect the Texture Colour Output connection to the Fac Input of the Mix Shader node. - Reconnect the same connection. - Now the pattern has disappeared. [Texture_with_alpha_renders_differently_bug.blend](https://archive.blender.org/developer/F8532574/Texture_with_alpha_renders_differently_bug.blend)

Zsolt Stefan commented

2020-05-13 09:34:42 +02:00

Added subscriber: @ZsoltStefan

Alaska commented

2020-05-13 09:39:47 +02:00

Added subscriber: @Alaska

Alaska commented

2020-05-13 09:39:47 +02:00

@ZsoltStefan To reproduce the bug with your .blend you need to pack all the textures into the .blend file. To do this, select from the top of Blender "File>External Data>Pack all into .blend" then save the file and re-share it.

Alaska commented

2020-05-13 09:42:25 +02:00

Changed status from 'Needs Triage' to: 'Needs User Info'

Zsolt Stefan commented

2020-05-13 11:09:42 +02:00

Oh, right, reuploaded.

Alaska commented

2020-05-13 11:18:28 +02:00

Changed status from 'Needs User Info' to: 'Needs Triage'

Alaska commented

2020-05-13 11:18:28 +02:00

@ZsoltStefan Thank you. As for your report about the bug, I can confirm this happens. Tested with Blender 2.82a and 2.90 f9d0f59bed (2020-05-12 22:14) with a GTX 1050ti driver version 440.82 on Linux.

@ZsoltStefan Thank you. As for your report about the bug, I can confirm this happens. Tested with Blender 2.82a and 2.90 f9d0f59bed (2020-05-12 22:14) with a GTX 1050ti driver version 440.82 on Linux.

Alaska commented

2020-05-13 12:02:16 +02:00

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

Ankit Meel commented

2020-05-13 12:23:04 +02:00

Added subscriber: @ankitm

Brecht Van Lommel commented

2020-05-13 15:20:44 +02:00

Added subscriber: @brecht

Brecht Van Lommel commented

2020-05-13 15:20:44 +02:00

Changed status from 'Confirmed' to: 'Resolved'

Brecht Van Lommel closed this issue

2020-05-13 15:20:44 +02:00

Brecht Van Lommel self-assigned this 2020-05-13 15:20:44 +02:00

Brecht Van Lommel commented

2020-05-13 15:20:44 +02:00

There is an intentional difference between Cycles and Eevee here, for reasons of performance and compatibility with game engines vs. offline renderers.

Some background on this is in #64625.

There is an intentional difference between Cycles and Eevee here, for reasons of performance and compatibility with game engines vs. offline renderers. Some background on this is in #64625.

Brecht Van Lommel commented

2020-05-13 15:20:52 +02:00

Changed status from 'Resolved' to: 'Archived'

Evan Wilson commented

2020-05-15 01:59:08 +02:00

Added subscriber: @EAW

Evan Wilson commented

2020-05-15 01:59:08 +02:00

Cycles

EEVEE

If you want to use the Alpha channel as a pattern, you should connect the alpha channel to the factor, not the color.

Texture_with_alpha_renders_differently_FIXED.blend

![Cycles.jpg](https://archive.blender.org/developer/F8536210/Cycles.jpg) Cycles ![EEVEE.jpg](https://archive.blender.org/developer/F8536212/EEVEE.jpg) EEVEE If you want to use the Alpha channel as a pattern, you should connect the alpha channel to the factor, not the color. [Texture_with_alpha_renders_differently_FIXED.blend](https://archive.blender.org/developer/F8536230/Texture_with_alpha_renders_differently_FIXED.blend)

Zsolt Stefan commented

2020-05-15 09:14:08 +02:00

@EAW thanks for the reply. I am aware how to solve the problem, I was trying to address these two bugs:

Eevee ("Material Preview") doesn't always "preview" a material in cycles. As Brecht says, in this case this seems to be intentional.
An unused node has an effect on the output. Don't see why this would be intentional.

@EAW thanks for the reply. I am aware how to solve the problem, I was trying to address these two bugs: 1. Eevee ("Material Preview") doesn't always "preview" a material in cycles. As Brecht says, in this case this seems to be intentional. 2. An unused node has an effect on the output. Don't see why this would be intentional.

Sign in to join this conversation.

No Label

Download

What's New

Blender Studio

Manual

Developers Blog

Documentation

Benchmark

Blender Conference

Development Fund

One-time Donations

Texture with alpha renders differently in Eevee and Cycles #76712