Old Crystals

The end crystals in the game were drawn differently before the 1.21.9 update. Since the 1.21.9 update, the entity renderer lights double-sided faces one face at a time, so the two spinning glass shells of an End Crystal, which are drawn without backface culling, came out shaded inside-out: the inner surface of the outer shell showed inverted light. Old Crystals restores the earlier shading for end crystals only, and other entities keep their vanilla shading.

A single mixin swaps end crystals onto that pipeline, so the mod runs vanilla's own shaders and adds no custom GLSL. Because it touches only textures and models in the client rendering path, gameplay is not changed, and the mod needs nothing beyond Fabric. It is client-side only, so servers run without it and players install it alone.

The rendering can be toggled with the command oldcrystals while the game is running, so players can compare the two looks without restarting. The source code is published, the code is under the MIT License, and the mod is open source. Files exist for Fabric only, for 1.21.9, 1.21.10, 1.21.11, 26.1, 26.1.1, 26.1.2 and 26.2, with 1.0.0 for 26.2 as the latest file.