Category Archives: html5

Zeta Pictograms

I have a set of ~100 pictograms that I use for personal notation. When I was actively working on Zeta. I created a few of these with equations:

You can read more about Zeta in this post.

I spam my facebook with images from my sketchbooks if you’re at all interested in seeing more pictograms:

Also posted in Graphics, graphics algorithms, javascript | Tagged , | Leave a comment

Dictionary with ES6 Symbol

Creating a dictionary type object with ES6 Symbols is easy. Yes we have Maps and WeakMaps but this is still interesting for a variety of reasons… Being able to use objects as keys in another object (dictionary) has many great uses…. So how do you use Symbols like this?

1
2
3
4
5
6
7
8
9
10
11
12
13
14
let a = { id: Symbol('key') },
    b = { id: Symbol('key') };
 
let dictionary = {
  [a.id]: 'value by obj a',
  [b.id]: 'value by obj b'
};
 
console.log(dictionary[a.id]);
console.log(dictionary[b.id]);
 
// outputs:
// 'value by obj a'
// 'value by obj b'

By using either object a or object b’s `id` symbol, our dictionary points to another value. This old AS3 snippet is similar:

http://actionsnippet.com/?p=426

Also posted in Dictionary, arrays, associative arrays, es6, javascript | Tagged , , , | Leave a comment

QuickShader Micro-Lib

In 2015 I created QuickShader… which just takes the boilerplate out of showing a shader in the browser. Here are a few examples:

Also posted in Graphics, Math, color, glsl, graphics algorithms, javascript, motion, pixel manipulation | Tagged , | Leave a comment

JavaScript Smooth Quadratic Bezier

Being able to draw smooth lines that connect arbitrary points is something that I find myself needing very frequently. This is a port of an old snippet that does just that. By averaging control points of a quadratic bezier curve we ensure that our resulting Bezier curves are always smooth.

The key can be seen here with the `bezierSkin` function. It draws either a closed or open curve.

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
// array of xy coords, closed boolean
function bezierSkin(bez, closed = true) {
  var avg = calcAvgs(bez), 
      leng = bez.length,
      i, n;
 
  if (closed) {
    c.moveTo(avg[0], avg[1]);
    for (i = 2; i < leng; i += 2) {
      n = i + 1;
      c.quadraticCurveTo(bez[i], bez[n], avg[i], avg[n]);
    }
    c.quadraticCurveTo(bez[0], bez[1], avg[0], avg[1]);
  } else {
    c.moveTo(bez[0], bez[1]);
    c.lineTo(avg[0], avg[1]);
    for (i = 2; i < leng - 2; i += 2) {
      n = i + 1;
      c.quadraticCurveTo(bez[i], bez[n], avg[i], avg[n]);
    }
    c.lineTo(bez[leng - 2], bez[leng - 1]);
  }
}
 
 
// create anchor points by averaging the control points
function calcAvgs(p) {
  var avg = [],
      leng = p.length, prev;
  for (var i = 2; i < leng; i++) {
    prev = i - 2;
    avg.push((p[prev] + p[i]) / 2);
  }
  // close
  avg.push((p[0] + p[leng - 2]) / 2);
  avg.push((p[1] + p[leng - 1]) / 2);
  return avg;
}

The control points are then averaged to ensure that the curve contains no sharp angles.

Also posted in Graphics, Math, arrays, bezier, graphics algorithms, javascript | Tagged , , , , | Leave a comment