Opaque Pre-Pass Problem with GLES3

[Saaamoth]

Godot version: 3.2.1

OS/device including version: Windows 10 / AMD Radeon R9 380 (Driver 20.3.1)

Issue description:
When using GLES3, in the SpatialMaterial parameters, setting the Depth Draw Mode to "Opaque Pre-Pass" while using alpha scissors results in alpha transparency problems :

• alpha cuts more than it should
• that alpha cut is stronger when moving the camera away from the object
• putting an object behind the alpha-cut surface sometimes helps, but not every time

Note : GLES2 gives normal results in Godot 3.2.1. I launched the scene with Godot 3.1 and all is normal both in GLES2 & 3

To illustrate that behaviour, left plane is "Opaque On" and right one is "Opaque Pre-Pass"

Here with an opaque background object

Steps to reproduce:

• Get an albedo map with an alpha channel
• Create a SpatialMaterial, in the parameters, use "Opaque Pre-Pass" and "Use Alpha Scissors"

Minimal reproduction project:

GodotOpaquePrePassProblem.zip

[clayjohn]

Duplicate of #36669

Please search existing issues before opening a new one! But thanks for the detailed report. It is still appreciated. :)

[Saaamoth]

Oops, my bad !