Sodium Core Shader Support

Enables resourcepacks to replace sodium's shaders, similar to resourcepacks being able to replace vanilla's core shaders.
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Documentation for Users

Sodium Core Shader Support allows resourcepacks to replace sodiums core shaders with their own. That does not mean, that
this mod makes every vanilla resourcepack work on sodium. The resourcepacks will only work if they specifically state, that
they are compatible with sodium core shader support.

If you are using a supported resourcepack you can simply activate it like any other resourcepack.

Resourcepack incompatible

Sodium may display the message The following resource packs are incompatible with Sodium in the top right corner after
reloading resources and listing your active core
shaders. This message will always appear, even if the resourcepack supports sodium core shaders and can be ignored.

List of Resourcepacks

This is a small list of resourcepacks that work on sodium. If you have created a resourcepack yourself feel free to
open an issue on my github to add it to this list!

• Energy Shaders [Java]
• Night Vision Shaders [Java]
• Re-Shaded (since re-shaded version 1.3)

Documentation for Shader Developers

It is important to understand that your vanilla shaders cannot just be copied to sodium shaders. Sodium has their own shaders
for blocks and clouds:

- assets/sodium/shaders/
   | - clouds.fsh
   | - clouds.vsh
   | - blocks/
        | - block_layer_opaque.fsh
        | - block_layer_opaque.vsh
   | - include/
        | - fog.glsl 
        | - chunk_material.glsl
        | - chunk_matrices.glsl
        | - chunk_vertex.glsl

Unless you want to change sodium clouds the block_layer_opaque are usually the most important ones.
You should not have to touch chunk_material.glsl, chunk_matrices.glsl and chunk_vertex.glsl unless you know what you
are doing.

Retrieving sodium shaders source code

To retrieve the sodium shader source code for a specific sodium version, download the .jar file of that version and
extract it like a .zip archive. Inside the extracted archive you will find a assets folder containing the directory
structure mentioned above.

block_layer_opaque

The block_layer_opaque is used for all blocks and block entities. The vanilla minecraft equivalent is terrain.fsh
and terrain.vsh (In older versions of minecraft the equivalent is rendertype_solid, rendertype_cutout, rendertype_cutout_mipped, ...).

Additionally, sodium core shader support adds a few defines in the sodium shaders block_layer_opaque.fsh
and block_layer_opaque.vsh for some terrain-types:

• RENDER_PASS_SOLID: Solid Blocks
• RENDER_PASS_CUTOUT: Blocks like leaves, grass, glass, ...
• RENDER_PASS_TRANSLUCENT: Blocks with actual transparency, e.g. water, honey, slime, ...

Furthermore, the define SODIUM_CORE_SHADER_SUPPORT will be present in all shaders (mc >= 1.21.2 and version >= 1.3.8).
These defines can be used like this:

#ifdef RENDER_PASS_SOLID
    // special shading for solid stuff
#endif

GameTime Uniform

As of Sodium Core Shader Support version 1.4.0 the u_GameTime uniform will be present in block_layer_opaque.fsh
and block_layer_opaque.vsh. It can be used just like the vanilla GameTime uniform. Add it to your shaders using:

uniform float u_GameTime;

SunAngle Uniform

As of Sodium Core Shader Support version 1.5.0 the u_SunAngle uniform will be present in block_layer_opaque.fsh
and block_layer_opaque.vsh as well. It returns the sun angle from environmental attributes in radians. Add it to your shaders using:

uniform float u_SunAngle;

How to specify which sodium versions are supported

The sodium devs will change their internal shaders and shader related code without further notice. That's why it is
important that you specify with which versions of sodium and minecraft your pack is compatible. This can be done in a special
versions.json file. It should be located in your resourcepack in a new directory assets/sodiumcoreshadersupport with
the file name versions.json inside. The contents of the file could look like this:

{
  "supported-versions": {
    "1.21": [ "0.5.11+mc1.21" ],
    "1.21.1": [ "0.5.11+mc1.21" ]
  }
}

In the above example the resourcepack states, that it is compatible with sodium 0.5.11 on minecraft 1.21 and 1.21.1.
An abstract description is below:

More specifically, versions.json must contain a question object with the key supported-versions.
The value of supported-versions must be a map, which maps different minecraft versions to an array of allowed sodium versions.
The SodiumCoreShaderSupport mod will check if the installed sodium version is contained in the array of the installed minecraft version.

• If the minecraft and/or sodium version is not inside supported-versions, the pack can be activated with a warning message.
• If the user does not have sodium installed the pack can be activated.
• If no versions.json is present, the pack can be activated with a warning message.
• If the versions.json is malformed, the pack can be activated with a warning message.

Imports

Sodium Shaders must be in assets/sodium/shaders directory. But you can #import files from
assets/minecraft/shaders using the #import directive. The following code will include
the file assets/minecraft/shaders/include/test.glsl:

#import <minecraft:include/test.glsl>

With this trick you can create custom glsl files, which you can #import in your shaders (in both core shaders and sodium shaders).
These files, should contain your main shader "logic". An example shaderpack, which
works with this trick on both vanilla and sodium, can be found here.

Disable Culling

Since version 1.5.0, sodium's frustum and backface culling can be disabled via versions.json. This is useful for any core shader that requires offscreen geometry, or that aims to transform the view in block.vsh to show geometry not typically on screen (e.g. shadows, alternate player POVs, etc.)

{
  "supported-versions": { "1.21.11": ["0.8.7+mc1.21.11"] },
  "disable-frustum-culling": true,
  "disable-backface-culling": true
}

Credits

Thanks to MR-CHOO for adding the SunAngle Uniform and the option
to disable frustum and backface culling!