Shader DevTools

Current version support is for Minecraft 26.4-snapshot-1 (Shader DevTools 1.3.18).

Client-side fabric mod for working on Minecraft core shaders, post shaders, post effects, and render pipelines without restarting the game or reloading the resource pack.

2026-04-08.02-07-21.mp4

Features

• In-game Shader DevTools menu, available with G by default, with reload, browser, inspector, override, and log tools
• Reload core shaders, post shaders, or both on demand without fully reloading the resource pack
• Quick core shader reload keybind, available with R by default
• Searchable core shader and post effect list, with overridden entries shown first
• Live editing of shader and post effect files in-game, with GLSL and JSON syntax highlighting
• Create editable overrides for vanilla/resource-pack shader sources, save them, delete editable sources, and copy source text
• When a shader exists in multiple packs, inspect each source individually and force the active source without changing pack order
• Quickly visualize fragment shader output by replacing the shader result with a debug view
• Parse post effect JSON files, edit them, and inspect their target/pass graph while editing
• Force a post effect from its detail screen for debugging, then release it without restarting the client
• Search and inspect all registered render pipelines, including shader links, vertex formats, samplers, uniforms, defines, targets, and depth/stencil state
• Inspect uniform bindings live
• Manually override Globals uniform values
• Inspect captured sampler bindings by pipeline, preview bound textures, read individual pixels, and copy 16x16 readbacks
• Live log viewer for the latest logs/latest.log lines
• On-screen debug summary for renderer, world, active post effect, globals overrides, and recent reload timings
• Shader debug logging via dbg(...) inside core and post shaders, with output written to the Minecraft log
• Local MCP server which can refresh shaders and take in-game screenshots

Shader Debug Logging

You can add calls like dbg("time=" + GameTime); to supported shader programs and the value will be written to logs/latest.log. It works on both OpenGL and Vulkan, supports ASCII, and you can do top level concatenation such as dbg("pos=" + WorldPos);. The mod will convert the value to a string itself.

MCP

The repository also includes a MCP server at mcp/csdt_mcp_server.py with tools for refresh_shaders and take_screenshot.