CanvasGLSL

CanvasGLSL

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

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

1. Install Fabric loader for Minecraft 1.21.10
2. Download the latest release JAR
3. Put it in your .minecraft/mods folder
4. 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

1. Copy shader code from Shadertoy
2. Paste into the editor
3. Click “Compile” or enable auto-compile
4. 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