expo-processing's Introduction

NOTE: GIF above looks weird some times because it's a GIF, the real thing is nice, I promise...

expo-processing

Use Processing.js on Expo! Just npm i -S processing-js expo-processing in your Expo project and import it with import { ProcessingView } from 'expo-processing;.

Components

`ExpoProcessing.ProcessingView`

Display a Processing.js sketch.

Props

The component accepts all View layout props for specifying its layout.

sketch: A Processing.js sketch function that takes a processing instance and calls Processing.js functions on it, such as the sketchProc function in the Processing.js documentation for writing JavaScript-only Processing.js code.

Example

This is based on the "In and out" sketch on OpenProcessing.org.

In a new blank Expo project, run npm i -S processing-js expo-processing to install Processing.js and ExpoProcessing. Then replace App.js with the following:

import React from 'react';
import { ProcessingView } from 'expo-processing';

export default class App extends React.Component {
  render() {
    return (
      <ProcessingView style={{ flex: 1 }} sketch={this._sketch} />
    );
  }

  _sketch = (p) => {
    p.setup = () => {
      p.strokeWeight(7);
    }

    const harom = (ax, ay, bx, by, level, ratio) => {
      if (level <= 0) {
        return;
      }

      const vx = bx - ax;
      const vy = by - ay;
      const nx = p.cos(p.PI / 3) * vx - p.sin(p.PI / 3) * vy;
      const ny = p.sin(p.PI / 3) * vx + p.cos(p.PI / 3) * vy;
      const cx = ax + nx;
      const cy = ay + ny;
      p.line(ax, ay, bx, by);
      p.line(ax, ay, cx, cy);
      p.line(cx, cy, bx, by);

      harom(
        ax * ratio + cx * (1 - ratio),
        ay * ratio + cy * (1 - ratio),
        ax * (1 - ratio) + bx * ratio,
        ay * (1 - ratio) + by * ratio,
        level - 1,
        ratio);
    }

    p.draw = () => {
      p.background(240);
      harom(
        p.width - 142, p.height - 142, 142, p.height - 142, 6,
        (p.sin(0.0005 * Date.now() % (2 * p.PI)) + 1) / 2);
    }
  }
}

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