# GLSL Imports Import GLSL functions from NPM packages, your files, or URLs using `#include` — no copy-pasting shader code between nodes. `#include` works across most visual objects: [glsl](/docs/objects/glsl), [swgl](/docs/objects/swgl), [regl](/docs/objects/regl), [hydra](/docs/objects/hydra) (inside `setFunction`), and [three](/docs/objects/three) (via `await glsl` tagged template). Write a utility once, use it everywhere. ## How It Works The `#include` directive inlines GLSL source code at the include site before shader compilation. It works like the C preprocessor: resolve the path, fetch the source, paste it in. ```glsl #include void mainImage(out vec4 fragColor, in vec2 fragCoord) { float n = snoise(vec3(uv * 4.0, iTime)); fragColor = vec4(vec3(n), 1.0); } ``` This fetches the `snoise` function from the [lygia](https://lygia.xyz) shader library and makes it available in your code. No setup needed — includes are resolved automatically. ## Import Sources There are three ways to import GLSL code: ### NPM Packages Use angle brackets to import from shader libraries like lygia: ```glsl #include #include #include ``` The `.glsl` extension is optional — `` and `` are equivalent. ### Your Files Use double quotes with a `user://` path to import from your [Virtual Filesystem](/docs/virtual-filesystem) files: ```glsl #include "user://my-shaders/utils.glsl" #include "user://sdf-functions.glsl" ``` Upload `.glsl` files through the sidebar (`Ctrl/Cmd + B > Files`), then include them in any shader node. ### URLs Use double quotes with a full URL to import from anywhere on the web: ```glsl #include "https://raw.githubusercontent.com/stegu/psrdnoise/main/src/psrdnoise2.glsl" ``` URL imports are cached in memory for the session, so they only fetch once. ## Supported Objects `#include` works in five visual objects — most of them auto-preprocess your shaders, so you just write `#include` and it works: | Object | How it works | | --- | --- | | [glsl](/docs/objects/glsl) | Auto-preprocessed before shader compilation | | [swgl](/docs/objects/swgl) | Auto-preprocessed in `FP`, `VP`, and `Inc` fields | | [regl](/docs/objects/regl) | Auto-preprocessed in `frag` and `vert` fields | | [hydra](/docs/objects/hydra) | Auto-preprocessed inside `setFunction` GLSL strings | | [three](/docs/objects/three) | Use `await glsl` tagged template or `processIncludes()` | ### Hydra Usage Use `#include` inside `setFunction` to bring external GLSL into Hydra's shader pipeline: ```javascript osc() .setFunction({ type: "frag", glsl: ` #include vec4 myEffect(vec4 color, vec2 uv) { float n = snoise(vec3(uv * 4.0, time)); return vec4(vec3(n), 1.0); } `, }) .out() ``` ### Three.js Usage Three.js nodes can't auto-preprocess because Patchies doesn't control `THREE.ShaderMaterial`. Use the `await glsl` tagged template instead: ```javascript const material = new THREE.ShaderMaterial({ fragmentShader: await glsl` #include void main() { float n = snoise(vec3(vUv * 4.0, time)); gl_FragColor = vec4(vec3(n), 1.0); } `, }) ``` The `glsl` tag and `processIncludes()` function are available in all JavaScript-based visual objects. ## Try It ### Exercise — Use lygia noise in a GLSL shader 1. Create a `glsl` object (`Enter` > type `glsl`) 2. Paste this code: ```glsl #include void mainImage(out vec4 fragColor, in vec2 fragCoord) { float n = snoise(vec3(uv * 5.0, iTime * 0.5)); fragColor = vec4(vec3(n * 0.5 + 0.5), 1.0); } ``` 3. Connect to `bg.out` — you should see animated simplex noise ### Exercise — Share a utility across nodes 1. Open the sidebar (`Ctrl/Cmd + B > Files`) and create a file called `utils.glsl` 2. Add a helper function: ```glsl vec3 palette(float t) { return 0.5 + 0.5 * cos(6.28318 * (t + vec3(0.0, 0.33, 0.67))); } ``` 3. In a `glsl` object, include and use it: ```glsl #include "user://utils.glsl" void mainImage(out vec4 fragColor, in vec2 fragCoord) { fragColor = vec4(palette(uv.x + iTime * 0.2), 1.0); } ``` 4. Create a second `glsl` object and include the same file — both nodes share the function ## Nested Includes Included files can contain their own `#include` directives. Resolution is recursive up to 32 levels deep. Circular includes are detected and produce an error. ## Caching - **NPM packages** are fetched from a CDN and cached for the session - **VFS files** are re-read when changed, so edits are reflected immediately - **URLs** are cached for the session (reload the page to re-fetch) ## Licensing: Lygia Shader Library Lygia is dual licensed under the [Prosperity License](https://prosperitylicense.com/versions/3.0.0) and the [Lygia Patron License](https://lygia.xyz/license). This means that Lygia is free for non-commercial use, i.e. for personal use and usage in non-commercial organizations. For _commercial_ use, please purchase a license from the creator, Patricio Gonzalez Vivo on [GitHub Sponsors](https://github.com/sponsors/patriciogonzalezvivo). This does NOT apply to you if you do not import the Lygia package by using `#include ` in your shaders. You can still use Patchies and all its features without importing Lygia. ## See Also - [glsl](/docs/objects/glsl) — fragment shaders with Shadertoy-compatible uniforms - [swgl](/docs/objects/swgl) — SwissGL shaders - [regl](/docs/objects/regl) — WebGL with REGL - [three](/docs/objects/three) — Three.js scenes - [Virtual Filesystem](/docs/virtual-filesystem) — managing files for `user://` imports

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