https://github.com/dy/gl-util
Set of practical webgl functions
https://github.com/dy/gl-util
webgl
Last synced: about 1 year ago
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Set of practical webgl functions
- Host: GitHub
- URL: https://github.com/dy/gl-util
- Owner: dy
- Created: 2016-11-30T08:53:59.000Z (over 9 years ago)
- Default Branch: master
- Last Pushed: 2025-01-18T21:39:44.000Z (over 1 year ago)
- Last Synced: 2025-03-28T16:06:28.374Z (about 1 year ago)
- Topics: webgl
- Language: JavaScript
- Size: 108 KB
- Stars: 27
- Watchers: 2
- Forks: 4
- Open Issues: 1
-
Metadata Files:
- Readme: readme.md
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README
# gl-util [](http://github.com/badges/stability-badges)
Set of practical functions for webgl.
[](https://npmjs.org/package/gl-util/)
```js
const u = require('gl-util');
let gl = u.context(canvas)
let prog = u.program(gl, `
precision mediump float;
attribute vec2 position;
void main() {
gl_Position = vec4(position * 2. - 1., 0, 1);
}
`, `
precision mediump float;
uniform vec4 color;
void main () {
gl_FragColor = color;
}
`);
u.attribute(prog, 'position', [0,0, 1,0, 0,1]);
u.uniform(prog, 'color', [1, .2, 0, 1.]);
gl.drawArrays(gl.TRIANGLES, 0, 3);
```
## API
### `context(container|canvas|options?)`
Create and/or return WebGL context for the canvas element, possibly based on options. If `container` is not defined, `document.body` is used.
| Option | Meaning |
|---|---|
| `canvas` | A canvas element to obtain context for. |
| `container` | An element to create canvas in and return context for it. |
| `width` | If specified, will set the canvas width. |
| `height` | If specified, will set the canvas height. |
| `pixelRatio` | Multiplier for `width` and `height`. |
| `attributes` | Attributes object. Available attributes: `alpha`, `depth`, `stencil`, `antialias`, `premultipliedAlpha`, `preserveDrawingBuffer` and `failIfMajorPerformanceCaveat`. |
```js
const getContext = require('gl-util/context')
// create canvas element in the document.body and retrieve context for it
let gl = getContext({
attributes: {
antialias: true
}
})
```
### `prog = program(gl, prog|vert?, frag?)`
Set active program or create a new program from vertex and fragment sources. Programs are cached for the context by source. The _WebGLProgram_ instance is returned.
```js
const program = require('gl-util/program')
// create and set program
let prog = program(gl, `
precision mediump float;
attribute vec2 position;
void main() {
gl_Position = vec4(position * 2. - 1., 0, 1);
}
`, `
precision mediump float;
uniform sampler2D image;
uniform vec2 shape;
uniform float x;
void main () {
gl_FragColor = texture2D(image, gl_FragCoord.xy / shape);
}
`)
// set active program
program(gl, prog)
```
### `unif = uniform(gl|program, {name: data, ...} | name?, data?)`
Get/set uniform or multiple uniforms. Returns an object with uniform parameters: `{name, location, data, type}`. Uniforms are stored per-program instance.
```js
const uniform = require('gl-util/uniform')
uniform(gl, 'color', [1, .2, 0, 1]);
```
### `txt = texture(gl, {name: params, ...} | name?, params?)`
Set texture[s] data or parameters:
| Name | Meaning |
|---|---|
| `data` | Data passed to texture. Can be array, typed array, image, canvas or string denoting the URL of image to load. |
| `index` | Texture unit number, if undefined - calculated automatically. |
| `filter` | Sets texture scaling for both min and mag. Can be defined as two separate properties `minFilter` and `magFilter`. By default `gl.LINEAR`. |
| `wrap` | Defines texture tiling vertically and horizontally. Can be defined precisely as `wrapS` and `wrapT`. By default `gl.CLAMP_TO_EDGE`, can be `gl.MIRRORED_REPEAT` or `gl.`. |
| `width` | In pixels |
| `height` | In pixels |
| `format` | `gl.ALPHA`, `gl.RGB`, `gl.RGBA` (default), `gl.LUMINANCE`, `gl.LUMINANCE_ALPHA`, `gl.DEPTH_COMPONENT`, `gl.DEPTH_STENCIL`, [etc](https://developer.mozilla.org/en-US/docs/Web/API/WebGLRenderingContext/texImage2D) |
| `type` | `gl.UNSIGNED_BYTE`, can be `gl.FLOAT` with proper extension enabled |
| `level` | `0`, mipmap level. |
Returns object with texture properties `{data, index, location, minFilter, magFilter, wrapS, wrapT, width, height, format, type, texture}`.
```js
const texture = require('gl-util/texture')
let {width, height} = texture(gl, 'image', './picture.gif');
```
### `attr = attribute(gl, {name: params, ...} | name?, params?)`
Set attribute[s] data or parameters:
| Name | Default | Meaning |
|---|---|---|
| `data` | `null` | Data for the attribute, can be array, typed array or array buffer |
| `size` | `2` | Number of data items per vertex |
| `stride` | `0` | Offset in bytes between the beginning of consecutive vertex attributes. |
| `offset` | `0` | Offset in bytes of the first component in the data. Must be a multiple of type. |
| `type` | `gl.FLOAT` | Data type of each component in the `data` array. Must be one of: `gl.BYTE`, `gl.UNSIGNED_BYTE`, `gl.SHORT`, `gl.UNSIGNED_SHORT`, `gl.FLOAT`. |
| `usage` | `gl.STATIC_DRAW` | Mode of draw: `gl.STATIC_DRAW` (rare changes), `gl.DYNAMIC_DRAW` (frequent changes) or `gl.STREAM_DRAW` (frequent updates) |
| `normalized` | `false` | If fixed-point data values should be normalized or are to converted to fixed point values when accessed. |
| `index` | `0` | Attribute unit number, detected automatically if omitted. |
| `target` | `gl.ARRAY_BUFFER` | |
| `buffer` | `null` | WebGLBuffer to use for attribute |
Returns attribute properties `{data, size, stride, offset, usage, type, normalized, index, target, buffer}`.
```js
const attribute = require('gl-util/attribute')
attribute(gl, 'position', [0,0,1,0,0,1]);
```
### `clear(gl, optsion?)`
Clear the viewport.
## Motivation
There are [regl](https://github.com/regl-project/regl), [stack.gl](https://github.com/stackgl/) and many other WegGL components or frameworks, so why gl-util?
* WebGL frameworks API is usually difficult to remember, not much better than pure WebGL, although _regl_ does a great job. _gl-util_ is like functions from any WebGL tutorial - tiny, handy and already familiar.
* _gl-util_ does not supersede WebGL API - that allows for debugging pure WebGL at any moment.
* _gl-util_ is tiny - if one needs minimalistic WebGL setup it may be better to opt for a couple of functions than massive stack.gl components or regl (70kb+).
* regl API may be cumbersome for organizing components
## License
(c) 2018 Dmitry Yv. MIT License
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