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Z-depth of transparent image planes in Eevee messed up
Closed, InvalidPublic

Description

System Information
Operating system: Linux-4.15.0-47-generic-x86_64-with-debian-buster-sid 64 Bits
Graphics card: GeForce GTX 1060 6GB/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 390.116

Blender Version
Broken: version: 2.80 (sub 55), branch: blender2.7, commit date: 2019-04-09 18:12, hash: rB009dbc2bc9fb
Worked: (optional)

Short description of error
With semi-transparent image planes (Alpha blend) using Eevee the Z-Depth gets messed up, both in viewport and render. Navigating around a stack of image planes separated in Z they constantly shift displayed position so the ones below is displayed above the top one. They shift around as you change your view.

They are displayed properly in the Workbench and Cycles-engines.
Opaque image planes does not have this issue in Eevee.

See attached video.

Exact steps for others to reproduce the error
Import a few images as planes. (Images as planes add-on, Shadeless, no offset)
Separate them in Z with a difference of about 0.2 and move them around a bit in X and Y ( it looks alright when they're stacked in the same position.)
Set the blend mode of all images to Alpha Blend.

Move around and watch the planes dance and shift visual position.

[Based on the default startup or an attached .blend file (as simple as possible)]

Details

Type
Bug

Event Timeline

Sebastian Parborg (zeddb) closed this task as Invalid.
Sebastian Parborg (zeddb) claimed this task.

This is a known limitation of alpha blend, you will have to use alpha hashed if you want to avoid issues like these.