CanvasGLSL

Replace Minecraft's menu backgrounds with custom GLSL shaders. Includes a built-in shader editor with syntax highlighting.

Embed Removed: https://www.youtube-nocookie.com/embed/KMdCm9JIzO0

Features

Live shader editor (press Insert to open)
Works on all menu screens (title, singleplayer, multiplayer, options, etc.)
Shadertoy compatible - paste shaders directly from Shadertoy
Auto-compile or manual compile modes
File manager for organizing shaders
Syntax highlighting

Installation

Install Fabric loader for Minecraft 1.21.10
Download the latest release JAR
Put it in your .minecraft/mods folder
Launch the game

Usage

Opening the Editor

Press Insert while in any menu to open the shader IDE. Press Insert or Esc to close it.

Writing Shaders

Shaders are saved in .minecraft/canvasglsl/. You can create folders to organize them.

Supported uniforms:

uniform float iTime; - Time in seconds
uniform vec3 iResolution; - Screen resolution (width, height, aspect)
uniform vec4 iMouse; - Mouse position (x, y, click x, click y)
uniform int iFrame; - Frame counter
uniform sampler2D iChannel0; - Procedural noise textures (iChannel0 through iChannel3)
uniform float iTimeDelta; - Time since last frame
uniform vec4 iDate; - Current date/time (year, month, day, seconds)
uniform float iSampleRate; - Audio sample rate (44100)

Example shader:

void mainImage(out vec4 fragColor, in vec2 fragCoord) {
    vec2 uv = fragCoord / iResolution.xy;
    vec3 col = 0.5 + 0.5 * cos(iTime + uv.xyx + vec3(0, 2, 4));
    fragColor = vec4(col, 1.0);
}

Using Shadertoy Shaders

Copy shader code from Shadertoy
Paste into the editor
Click "Compile" or enable auto-compile
Done! The shader will render as your menu background

Controls

Insert - Toggle shader editor
Esc - Close editor
Ctrl+S - Save current shader
Compile button - Compile shader manually
Auto-compile toggle - Auto-compile on save