Minecraft version
1.16.3

Mod version and malilib version

• malilib-fabric-1.16.3-0.10.0-dev.21+arne.1.jar
• litematica-fabric-1.16.3-0.0.0-dev.20200913.215807
• fabric-api-0.22.1+build.409-1.16.jar
• OptiFine_1.16.3_HD_U_G3.jar
• optifabric-1.6.4.jar

Description of the bug
I just installed Litematica to get some schematics in my game and when following a tutorial I placed a preview that was not rendering as it should to say the least, check the screenshot. I already suspected Optifine to be the cause of this so I disabled that mod and as expected it started working like it should.

To Reproduce
Simply install these versions of the different mods and try to load in a schematic. I also have 3 extra mods installed (borderless-mining, Xaeros Minimap and Xaeros WorldMap) but since these don't affect block rendering they are most likely not involved in this.

Screenshots

Try disabling shaders

it's the same for me, but I also tried the shaders thing to see if it helped but it didn't help at all. So I don't know what I can do to fix it.

In OptiFine settings:

Shaders needs to be disabled
Render Regions needs to be disabled
Fast Render might also need to be disabled if there are still some weird HUD/GUI rendering issues

also you have to restart the game after changing these options.

I had the same problem and following these steps helped me.

Thanks, that fixed it :). I will be keeping this issue open though as a workaround does not mean that the actual bug is fixed

One way to look at this is that it's not a bug as things work correctly in a "vanilla" setting, and only break after Optifine changes around rendering stuff when shaders are enabled.

However obviously it would be nice if both mods would work together. And the strange part is that in my 1.16.3 test instance I can use shaders without Litematica rendering breaking. But for quite a lot of people shaders seem to break the schematic rendering ever since 1.16.2 or even 1.16.1. I did some changes in 1.15.2 which at least at that time fixed the rendering with shaders, whereas before those changes it was always broken if you changed the shaders enabled state after starting the game (on -> off or vice versa). So I'm not sure what is going on with it, and Optifine being a closed source blob of problems it doesn't make it easy to figure out.

But I'll try to take a look at this once I do the next update from 1.12.2 to the later versions again, as I would like to do a bunch of schematic rendering related rewrites in general to clean up some stuff and fix some other issues as well.

I have the same problem on optifine and optifabric, minecraft 1.16.3

I had to restart the game too

Maybe it's an Optifine problem