@use-gpu/shader

``sh
npm install --save @use-gpu/shader
`

`sh
yarn add @use-gpu/shader
`

Docs: https://usegpu.live/docs/reference-library-@use-gpu-shader

WGSL / GLSL Linker and Tree Shaker

A Typescript library to link together snippets of shader code, while removing dead code, very quickly. It supports both WGSL and GLSL, but it will only link code within a single language.

It enables two kinds of imports to be used:

Static - Symbol Import (functions, declarations and types)

`wgsl
// WGSL
use 'path/to/color'::{ getColor };
`

`glsl
// GLSL
#pragma import { getColor } from 'path/to/color'
`

Dynamic - Function Prototype - Defined at run-time

`wgsl
// WGSL
@link fn getColor() -> vec4 {};
`

`glsl
// GLSL
vec4 getColor();
`

This allows you to split up and organize your WGSL / GLSL code as you see fit, as well as create dynamic shader permutations. It also lets you bind shaders at run-time without immediate linking, thus providing an equivalent of WGSL / GLSL closures.

@use-gpu/shader supports GLSL 4.5 and WGSL 0.x (provisional). It uses custom Lezer grammars for the parsing.

#### Bundler

When combined with @use-gpu/wgsl-loader or @use-gpu/glsl-loader, you can import a tree of .wgsl / .glsl modules directly in JS/TS as a pre-packaged bundle:

`ts
// WGSL in JS/TS
import mainShader from 'path/to/main.wgsl';

import { linkBundle } from '@use-gpu/shader/wgsl';
const wgslCode = linkBundle(mainShader);
`

`ts
// GLSL in JS/TS
import mainShader from 'path/to/main.glsl';

import { linkBundle } from '@use-gpu/shader/glsl';
const glslCode = linkBundle(mainShader);
`

All dependencies will be parsed at build-time and deduplicated, using the normal import mechanism. They are packed with their symbol table and a sparse token list, so that code generation can happen immediately without re-parsing.

#### Closures

Bind shaders to each other using bindBundle. This returns a new module instead of immediately producing the linked shader code. The result acts as a WGSL / GLSL closure that you can use as a first-class value in your program:

`ts
const bound = bindBundle(bundle, {moduleA, moduleB});
`

The bound module can be passed around, and used as a new link to bind to another module recursively. This is highly useful to e.g. abstract over data sources or decorate shaders with new behavior.

#### Template literals

Use wgsl or glsl template literals to embed shaders inline:

`tsx
import { wgsl } from '@use-gpu/shader/wgsl';

const wgslModule = wgsl
fn main() {}
;
`

`tsx
import { glsl } from '@use-gpu/shader/glsl';

const glslModule = glsl
void main() {}
;
`

This is equivalent to a loadModuleWithCache call, so recent modules are cached by text hash. The default entry point is main.

Use bindEntryPoint(module, 'entryPoint') to bind different entry points.

Use f32(x), u32(x) and i32(x) to format JS numbers correctly as WGSL strings (and float, uint, int for GLSL):

`tsx
import { wgsl, u32 } from '@use-gpu/shader/wgsl;

const module = wgsl
fn main() -> u32 { return ${u32(1)}; } // "1u"
fn other() -> f32 { return ${f32(1)}; } // "1.0"
;
``

Imports (use / #pragma import) do not work inside template literals, as they are parsed at run-time. Instead, import the WGSL symbols in JS, and use bindBundle to link them to the wgsl snippet:

`tsx
import { SurfaceFragment } from '@use-gpu/wgsl/use/types.wgsl';

const mainShader = bindBundle(wgsl
@link struct SurfaceFragment {};

fn main() -> SurfaceFragment {
// ...
}
, {SurfaceFragment});
`

#### Strings

You can skip the bundler and work with raw strings. In this case it is up to you to gather all the associated module code:

`ts
import { linkCode } from '@use-gpu/shader/wgsl';

const moduleA = "...";
const moduleB = "...";
const moduleC = "...";

const linked = linkCode(moduleC, {moduleA, moduleB});
`

Shaders parsed at run-time will be cached on a least-recently-used basis, based on content hash.

Syntax (WGSL)

#### Linking

`wgsl
// Import symbols from a .wgsl file
use "path/to/file"::{ symbol, … };
use "path/to/file"::{ symbol as symbol, … };

// Function is linked at runtime. Function body is ignored and may be omitted.
@link fn func();

// Declaration is exported (can be linked to)
@export fn func() { };

// Function is linked at runtime but optional.
// Function body is used if not linked.
@link @optional fn func() -> f32 { return 1.0; }

// Type is linked at runtime
@link struct Type { };

// Storage binding is linked at runtime
@link var storageVar: array;

// Declaration is global (don't namespace it)
@global fn func() -> f32 { return 1.0; }
@global var name : i32;
`

#### Type Inference (WGSL only)

`wgsl
// Inferred type T
@infer type T;

// Infer T from linked argument type or return type
@link fn func(arg: @infer(T) T) -> f32 {}
@link fn func() -> @infer(T) T {}

// Inferred type T can be used throughout the .wgsl file
fn other(arg: T) -> T {
// ...
}
`

Syntax (GLSL)

`glsl
// Import symbols from a .glsl file
#pragma import { symbol, … } from "path/to/file"
#pragma import { symbol as symbol, … } from "path/to/file"

// Mark next declaration as exported
#pragma export

// Mark next function prototype as optional (e.g. inside an #ifdef)
#pragma optional

// Mark next declaration as global (don't namespace it)
#pragma global
`

Example

#### Static Import

Imports from other files are declared using a Rust or ES-style directive referencing the filesystem:

main.wgsl
`wgsl
use 'path/to/color'::{ getColor };

fn main() -> vec4 {
return getColor();
}
`

main.glsl
`glsl
#pragma import { getColor } from 'path/to/color'

void main() {
gl_FragColor = getColor();
}
`

Only exported symbols may be imported:

path/to/color.wgsl
`wgsl
@export fn getColor() -> vec4 {
return vec4(used(), 0.5, 0.0, 1.0);
}

fn used() -> f32 {
return 1.0;
}

fn unused() {
// ...
}
`

path/to/color.glsl
`glsl
#pragma export
vec4 getColor() {
return vec4(used(), 0.5, 0.0, 1.0);
}

float used() {
return 1.0;
}

void unused() {
// ...
}
`

When passed to linkBundle, the result is:

Linked result

`wgsl
fn _u4_getColor() -> vec4 {
return vec4(_u4_used(), 0.5, 0.0, 1.0);
}

fn _u4_used() -> f32 {
return 1.0;
}

fn main() -> vec4 {
return _u4_getColor();
}
`

`glsl
#version 450

vec4 _u4_getColor() {
return vec4(_u4_used(), 0.5, 0.0, 1.0);
}

float _u4_used() {
return 1.0;
}

void main() {
gl_FragColor = _u4_getColor();
}
`

All top-level symbols outside the main module are namespaced with a prefix like _u4_ to avoid collisions, unless marked as global.

#### Dynamic

For dynamic linking at run-time, you link up with a function prototype instead:

main.wgsl
`wgsl
@link fn getColor() -> vec4;

fn main() -> vec4 {
return getColor();
}
`

main.glsl
`glsl
vec4 getColor();

void main() {
gl_FragColor = getColor();
}
`

Import named symbols from .wgsl or .glsl files in JS/TS, and use them directly as links:

`ts
import mainShader from 'path/to/main.wgsl';
import { getColor } from 'path/to/color.wgsl';

const wgslCode = linkBundle(mainShader, {getColor});
`

`ts
import mainShader from 'path/to/main.glsl';
import { getColor } from 'path/to/color.glsl';

const glslCode = linkBundle(mainShader, {getColor});
`

The linking mechanism works the same.

Q&A

Which 'version' of WGSL is supported?

Best-effort compatibility with the current dialect of WGSL supported in the wild. If there are gaps in the grammar, let me know.

Does this interpret GLSL pre-processor directives? (GLSL)

No. It ignores and passes through all other #directives. This is done to avoid having to re-parse when definitions change.

This means the linker sees all top-level declarations regardless of #ifs, and resolves all imports.

Mark prototypes as #pragma optional if it is ok to leave them unlinked.

Isn't it silly to ship and work with strings instead of byte code?

Processing pre-parsed WGSL / GLSL bundles is very fast and simple, even with tree shaking. Rewriting a SPIR-V program the same way is much more fiddly.

API

$3

Returns linked GLSL code by assembling:

- code / module / bundle: Main module.
- modules: Dictionary of modules to import manually from. { [path]: T }
- links: Dictionary of modules to link specific prototypes to. { [name]: T }
- defines: Dictionary of key/values to const / #define at the start.
- cache: Override the internal cache or disable it.

Use from:to as the link name to link two differently named functions.
This is equivalent to a static import { $to as $from } ....

#### linkCode(…)

Link direct source code.

`ts
(
code: string,
modules: Record = {},
links: Record = {},
defines: Record = {},
cache?: LRU | null,
) => string;
`

#### linkModule(...)

Link parsed modules.

`ts
(
module: ParsedModule,
modules: Record = {},
links: Record = {},
defines: Record = {},
) => string;
`

#### linkBundle(...)

Link packaged bundle of module + libs.

`ts
(
bundle: ParsedBundle | ParsedModule,
links: Record = {},
defines: Record = {},
) => string;
`

#### setPreamble(…) (GLSL only)

`ts
(s: string) => void
`

Replace the global #version 450 preamble with another string.

$3

Bind modules/bundles together into a new bundle at run-time.

`tsx
const bound = bindBundle(bundle, {links});
`

This is a fast operation which only affects the top-level module in a bundle.

The resulting bundle acts as a closure. Then link or rebind it:

`tsx
// Link it into a shader
linkBundle(mainBundle, {getData: bound});

// Bind it and make new module
const otherBound = bindBundle(otherBundle, {getData: bound});
`

#### bindBundle(...)

`ts
(
bundle: ShaderModule,
links: Record = {},
defines?: Record | null,
) => ParsedBundle;
`

#### bindModule(...)

`ts
(
main: ParsedModule,
libs: Record = {},
links: Record = {},
defines?: Record | null,
) => ParsedBundle;
`

$3

Specify entry to point to a specific symbol as entry point.

#### loadModule(…)

Parse a code module into its in-memory representation (AST + symbol/shake table).

`ts
(
code: string,
name: string,
entry?: string,
compressed: boolean = false,
) => ParsedModule;
`

#### loadModuleWithCache(…)

Load a module from the given cache, or parse it if missing.

`ts
(
code: string,
name: string,
entry?: string,
cache: LRU | null = null,
) => ParsedModule;
`

#### makeModuleCache(...)

Wrapper around npm LRU.

Colofon

Made by Steven Wittens. Part of @use-gpu`.