# 
[](https://www.npmjs.com/package/@thi.ng/shader-ast-optimize)
[](https://mastodon.thi.ng/@toxi)
> [!NOTE]
> This is one of 205 standalone projects, maintained as part
> of the [@thi.ng/umbrella](https://github.com/thi-ng/umbrella/) monorepo
> and anti-framework.
>
> 🚀 Please help me to work full-time on these projects by [sponsoring me on
> GitHub](https://github.com/sponsors/postspectacular). Thank you! ❤️
- [About](#about)
- [defOptimized()](#defoptimized)
- [Tree optimizations](#tree-optimizations)
- [Constant folding](#constant-folding)
- [Status](#status)
- [Installation](#installation)
- [Dependencies](#dependencies)
- [Usage examples](#usage-examples)
- [API](#api)
- [Authors](#authors)
- [License](#license)
## About
Shader AST code optimization passes/strategies. This is a support package for [@thi.ng/shader-ast](https://github.com/thi-ng/umbrella/tree/develop/packages/shader-ast).
### defOptimized()
The function
[`defOptimize()`](https://docs.thi.ng/umbrella/shader-ast-optimize/functions/defOptimized.html)
can be used as direct replacement for [thi.ng/shader-ast]()'s
[`defMain()`](https://docs.thi.ng/umbrella/shader-ast/functions/defMain.html) to
define automatically optimized shader `main()` functions.
### Tree optimizations
Currently, only the following operations are supported/considered:
#### Constant folding
- scalar math operators (incl. some vector versions)
- scalar math built-in functions (incl. some vector versions)
- scalar comparisons
- single component vector swizzling
- literal hoisting
(See tests for some more examples, non-exhaustive...)
**Note:** The static optimizer throws an error if it detects a division-by-zero...
```ts tangle:export/readme1.ts
import {
add, defn, float, mul, neg, ret, scope, vec2, $x, $y
} from "@thi.ng/shader-ast";
import { targetGLSL } from "@thi.ng/shader-ast-glsl";
import { constantFolding } from "@thi.ng/shader-ast-optimize";
// function def
const foo = defn("float", "foo", ["float"], (x) => [
ret(mul(x, add(neg(float(10)), 42)))
]);
const bar = vec2(100, 200);
// program def
const prog = scope([
foo,
foo(add(float(1), float(2))),
foo(add($x(bar), $y(bar)))
], true);
// GLSL codegen
const glsl = targetGLSL();
// unoptimized AST as GLSL (see section above)
console.log(glsl(prog));
// #version 300 es
// float foo(in float _s0) {
// return (_s0 * ((-10.0) + 42.0));
// }
// foo((1.0 + 2.0));
// foo((vec2(100.0, 200.0).x + vec2(100.0, 200.0).y));
// with constant folding
console.log(glsl(constantFolding(prog)))
// #version 300 es
// float foo(in float _s0) {
// return (_s0 * 32.0);
// }
// foo(3.0);
// foo(300.0);
const expr = mul(float(4), $x(vec2(2)))
console.log(glsl(expr))
// (4.0 * vec2(2.0).x)
// optimize single expression
console.log(glsl(constantFolding(expr)))
// 8.0
```
## Status
**STABLE** - used in production
[Search or submit any issues for this package](https://github.com/thi-ng/umbrella/issues?q=%5Bshader-ast-optimize%5D+in%3Atitle)
## Installation
```bash
yarn add @thi.ng/shader-ast-optimize
```
ESM import:
```ts
import * as opt from "@thi.ng/shader-ast-optimize";
```
Browser ESM import:
```html
```
[JSDelivr documentation](https://www.jsdelivr.com/)
For Node.js REPL:
```js
const opt = await import("@thi.ng/shader-ast-optimize");
```
Package sizes (brotli'd, pre-treeshake): ESM: 1.26 KB
## Dependencies
- [@thi.ng/api](https://github.com/thi-ng/umbrella/tree/develop/packages/api)
- [@thi.ng/defmulti](https://github.com/thi-ng/umbrella/tree/develop/packages/defmulti)
- [@thi.ng/errors](https://github.com/thi-ng/umbrella/tree/develop/packages/errors)
- [@thi.ng/logger](https://github.com/thi-ng/umbrella/tree/develop/packages/logger)
- [@thi.ng/math](https://github.com/thi-ng/umbrella/tree/develop/packages/math)
- [@thi.ng/shader-ast](https://github.com/thi-ng/umbrella/tree/develop/packages/shader-ast)
Note: @thi.ng/api is in _most_ cases a type-only import (not used at runtime)
## Usage examples
One project in this repo's
[/examples](https://github.com/thi-ng/umbrella/tree/develop/examples)
directory is using this package:
| Screenshot | Description | Live demo | Source |
|:----------------------------------------------------------------------------------------------------------------------|:---------------------------------------------------------|:-----------------------------------------------------|:----------------------------------------------------------------------------------|
| 
| Evolutionary shader generation using genetic programming | [Demo](https://demo.thi.ng/umbrella/shader-ast-evo/) | [Source](https://github.com/thi-ng/umbrella/tree/develop/examples/shader-ast-evo) |
## API
[Generated API docs](https://docs.thi.ng/umbrella/shader-ast-optimize/)
TODO
## Authors
- [Karsten Schmidt](https://thi.ng)
If this project contributes to an academic publication, please cite it as:
```bibtex
@misc{thing-shader-ast-optimize,
title = "@thi.ng/shader-ast-optimize",
author = "Karsten Schmidt",
note = "https://thi.ng/shader-ast-optimize",
year = 2019
}
```
## License
© 2019 - 2025 Karsten Schmidt // Apache License 2.0