[PortalGun] Weird visual glitches with OptiFine SEUS shader

[Voldemort127]

I found this bug in my own modpack of ~160 mods in minecraft 1.12.2. I have the newest version of OptiFine installed and the SEUS shader enabled. In the portal gun config file, both 'fancyPortals' and 'seeThroughPortals' are enabled. When I place the first portal, it seems fine, but when I place the second one, I get to experience the effects of LSD (video).

I have also tried it in a new minecraft instance, with only OptiFine, iChunUtil an PG installed, but I got the same result.

• PG version: 1.12.2-7.0.2
• iChunUtils version: 1.12.2-7.1.4
• OptiFine Version: HD_U_D3
• Operating System: Windows 10 Enterprise 1803
• Tested in Singleplayer
• GPU: GTX 1060 6Gb, GeForce Driver: 397.93
• Java version: 1.8.0_172

The game logs can be found here. Note that the GLSL messages between lines 490 and 860 appeared while the world was loading, and after that no new logs appeared before I closed the game.

I know that it is very difficult to make a mod like this work with shaders, but I'm hoping that there is a fix.

[Gumballegal]

same problem. i've seen that "fast render" in optifine performance options make this problem hppen, with or without shaders. is there a way to disable this with shaders? cound't find an option like so in the shaders options.