2327e6cc5d
* docs(guide): minor edits to animation-in-canvas * Use ES6 syntax in code examples * Clean up formatting in code examples for clarity * Remove unnecessary sentence for brevity * docs(guide): use arrow functions for canvas animation examples
48 lines
1.1 KiB
Markdown
48 lines
1.1 KiB
Markdown
---
|
|
title: Animation
|
|
---
|
|
## Animation in Canvas
|
|
|
|
To animate things in `canvas`, use `window.requestAnimationFrame` to set up a draw loop.
|
|
|
|
```js
|
|
const draw = () => {
|
|
/* code goes here */
|
|
window.requestAnimationFrame(draw);
|
|
};
|
|
window.requestAnimationFrame(draw);
|
|
```
|
|
|
|
`canvas` has no special functions that allow for animating. You just have to be used to writing in animation loops. The usual design paradigm for animation loops is to update the state, then draw the state. For instance, to draw a square moving across the screen:
|
|
|
|
```js
|
|
const canvas = document.getElementById('canvas');
|
|
const ctx = canvas.getContext('2d');
|
|
|
|
const y = 50;
|
|
let x = 0;
|
|
const draw = () => {
|
|
// reset canvas
|
|
ctx.clearRect(0, 0, canvas.width, canvas.height);
|
|
|
|
// update state
|
|
x += 1;
|
|
|
|
// render state
|
|
ctx.beginPath();
|
|
ctx.rect(x, y, 50, 50);
|
|
ctx.fill();
|
|
|
|
window.requestAnimationFrame(draw);
|
|
};
|
|
window.requestAnimationFrame(draw);
|
|
```
|
|
|
|
To see this concept in action, see the [Particle Sim](/articles/canvas/particle-sim) page.
|
|
|
|
#### More Information:
|
|
|
|
- [MDN Canvas API](https://developer.mozilla.org/en-US/docs/Web/API/Canvas_API)
|
|
|
|
|