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}
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Cut Hole in Canvas (eraser)

  1. document.body.style.background = 'gray';
  2. const canvas = document.createElement('canvas');
  3. const c = canvas.getContext('2d');
  4.  
  5. canvas.width = 300;
  6. canvas.height = 300;
  7.  
  8. c.fillStyle='rgba(255, 0, 0, 0.8)'
  9. c.fillRect(0, 0, canvas.width, canvas.height);
  10.  
  11. c.globalCompositeOperation = 'destination-out';
  12. c.fillStyle = 'black';
  13. c.fillRect(100, 100, 150, 50);
  14.  
  15. document.body.appendChild(canvas);

destination-out is great for creating masks and eraser tools – things like that – in this case a 150×50 rectangle is cut out of a red background.

Odd Gradient Notation

  1. // "Being clever is not clever"
  2. // -- Bjarne Stroustrup
  3. D = document
  4. ang = {
  5.   '|': 180,
  6.   '-': 90,
  7.   '\\': 135,
  8.   '/': 225
  9. }
  10.  
  11. box = def => {
  12.   def = def.split(/\s+/)
  13.   form = def.length
  14.   I = i => parseInt(def[i], 16)
  15.  
  16.   ;[,,, _=>{x = y = I(0); w = h = I(1); c = def[2]},
  17.     _=>{x = I(0), y = I(1); w = h = I(2);c = def[3]},
  18.     _=>{x = I(0); y = I(1); w = I(2); h = I(3); c = def[4]}
  19.   ][form]()
  20.  
  21.   c = c.split``
  22.  
  23.   ca = c[0]
  24.   ca = ca+ca+ca
  25.   cD = ang[c[1]]
  26.   cb = c[2]
  27.   cb = cb+cb+cb 
  28.  
  29.   D.body.appendChild(
  30.     D.createElement`div`
  31.   ).style = `
  32.     position: absolute; left: ${x}px; top: ${y}px;
  33.     width: ${w}px; height: ${h}px;
  34.     background: linear-gradient(${cD}deg, #${ca}, #${cb})
  35.   `
  36. }
  37.  
  38. const parse = prog => prog.trim()
  39.   .split(/\n+/m)
  40.   .map(line => box(line.trim()))
  41.  
  42. parse(`
  43.   0 64 0/f
  44.   64 64 0\\f
  45.   a0 f0 30 54 f\\0
  46.   0 6f 20 60 0-c
  47.   f 7f 20 60 0|c
  48.   1f 8f 30 30 c/0
  49. `)

Just playing around… odd micro-gradient notation:

  1. '0 64 0/f'
  2. // x=0 y=0 width=0x64 height=0x64
  3. // 0/f = gradient black to white top right to bottom left
  4.  
  5. '64 64 0\\f'
  6. // x=0 y=0 width=0x64 height=0x64
  7. // 0\\f = black to to white gradient top left to bottom right
  8.  
  9. '0 6f 20 60 0-c'
  10. // x=0 y=0x6f width=0x20 height=0x60
  11. // 0-c = gradient black to grey (#ccc) left to right
  12.  
  13. // etc... ( | ) is top to bottom grad
// css // dom // golfed // graphics // hacks // humor // regex // speed-coded

Isometric Vases

  1.  
  2. const canvas = document.createElement`canvas`
  3. const c = canvas.getContext`2d`
  4.  
  5. document.body.appendChild(canvas)
  6. document.body.style.margin = 0
  7.  
  8. canvas.style.width = '100%'
  9. canvas.style.height = '100%'
  10.  
  11. const COLS = 10
  12. const ROWS = 10
  13. let space;
  14. let size;
  15. let time = 0
  16. const num = COLS * ROWS
  17. const mon = []
  18. for (let y = 0; y < COLS; y++) {
  19.   for (let x = 0; x < ROWS; x++) {
  20.     mon.push(monument())
  21.   }
  22. }
  23.  
  24. function reset(){
  25.   time = 0
  26.   c.fillStyle = '#ccc'
  27.   c.fillRect(0, 0, canvas.width, canvas.height)
  28. }
  29.  
  30. function resize() {
  31.   canvas.width = innerWidth * 2
  32.   canvas.height = innerHeight * 2
  33.  
  34.   reset()
  35. }
  36. resize()
  37. window.addEventListener('resize', resize)
  38.  
  39. function monument(x, y) {
  40.  
  41.   const s = Math.random()
  42.   let cl = 0;
  43.   let damp = Math.random() / 10;
  44.  
  45.   let rad = 10 + Math.random() * 
  46.   Math.random() * (innerWidth / 30)
  47.  
  48.   let skip = Math.random() < .5;
  49.   let o = Math.random() * 7
  50.   let shade = .01;
  51.   let radamp = 200 + Math.random() * 90
  52.   let life = 100 + Math.random() *  Math.random() *  Math.random() * 1200;
  53.   return (x, y) => { 
  54.       if (time === 0) { 
  55.       c.save()
  56.       c.strokeStyle = 'rgba(0, 0, 0, 0.2)'
  57.       c.translate(x - space / 2, y - space / 2)
  58.       c.strokeRect(0, 0, space, space)
  59.       c.restore()
  60.       }
  61.     if (skip) {
  62.  
  63.  
  64.     } else { 
  65.  
  66.       //rad += (0 - rad) / radamp
  67.       let teta = time * s * damp
  68.       let C = Math.sin(teta)
  69.       let C2 = Math.sin(time * s * damp + o);
  70.  
  71.       cl = C2 * 200 + 55;
  72.  
  73.       shade -= .0001;
  74.  
  75.       let col = `rgba(${cl}, ${cl}, ${cl}, 1)`
  76.       if (time > life) {
  77.         col = `rgba(155, 155, 155, .4)`
  78.         skip = true
  79.       }
  80.  
  81.     c.save()
  82.  
  83.       c.translate(x - time * s, y)
  84.       c.fillStyle = `rgba(0, 0, 0, ${shade})`
  85.       c.beginPath()
  86.       c.arc(0, 0, rad + rad * C, 0, 7)
  87.       c.fill()
  88.       c.restore();
  89.  
  90.       c.save()
  91.  
  92.       c.translate(x - time * s, y - time * s)
  93.       c.fillStyle = col
  94.       c.beginPath()
  95.       c.arc(0, 0, rad + rad * C, 0, 7)
  96.       c.fill()
  97.       c.restore();
  98.     }
  99.   }
  100. }
  101.  
  102. function draw() {
  103.   space = (innerWidth * 2) / COLS * .6;
  104.  
  105.   size = COLS * space
  106.  
  107.   c.save()
  108.   c.scale(1, .6)
  109.   c.translate(innerWidth, innerHeight * 2)
  110.   c.rotate(45 * Math.PI / 180)
  111.   c.translate(-size / 2, -size / 2)
  112.  
  113.   let inc = 0;
  114.   for (let y = 0; y < COLS; y++) {
  115.     for (let x = 0; x < ROWS; x++) {
  116.       mon[inc++](y * space, x * space)
  117.     }
  118.   }
  119.   c.restore()
  120.   time++
  121.   requestAnimationFrame(draw)
  122. }
  123.  
  124. draw();

Something I speed coded for genuary

CoffeeScript Ikeda Map

  1. canvas = document.querySelector "canvas"
  2. c = canvas.getContext "2d"
  3. locX = 120
  4. locY = 400
  5. xn1 = xn = yn1 = yn = tn = 0
  6. u = .7
  7. steps = 10
  8. iterations = 200
  9. scale = 180
  10.  
  11. c.fillStyle = "black"
  12. c.fillRect 0, 0, canvas.width, canvas.height
  13. c.fillStyle = "rgba(255,255,255,0.2)"
  14.  
  15. run = setInterval ->
  16.   clearInterval run if u > 1
  17.   i = 0
  18.  
  19.   while i < steps
  20.     u += 0.00015
  21.     j = 0
  22.  
  23.     while j < iterations
  24.       xn = xn1
  25.       yn = yn1
  26.       tn = 0.4 - (6 / (1 + xn * xn + yn * yn))
  27.       xn1 = 1 + u * (xn * Math.cos(tn) - yn * Math.sin tn)
  28.       yn1 = u * (xn * Math.sin(tn) + yn * Math.cos tn)
  29.       c.fillRect locX + xn1 * scale, locY + yn1 * scale, 1, 1
  30.       j++
  31.     i++
  32. , 30

I do quite miss CoffeeScript sometimes… here is an old codepen of the Ikeda Map:

See the Pen Ikeda Map by Zevan Rosser (@ZevanRosser) on CodePen.

Little Galaxy ES5

  1. var canvas = document.createElement('canvas'), 
  2.     c = canvas.getContext('2d'), 
  3.     SIZE = 350;
  4.  
  5. canvas.width = SIZE;
  6. canvas.height = SIZE;
  7.  
  8. document.body.appendChild(canvas);
  9.  
  10. c.fillStyle = 'black';
  11. c.fillRect(0, 0, SIZE, SIZE);
  12.  
  13. c.fillStyle = 'white';
  14.  
  15. var spa = function(ts) {
  16.   var r = 0, t =  0;
  17.   var jitterX, jitterY, jitterT, jitterR;
  18.   for (var i = 0; i < 100; i += 0.5) {
  19.     t = ts + i / 15;
  20.     r = i;
  21.     jitterR = 5 + i / 5;
  22.     jitterT = Math.random() * 2 * Math.PI;
  23.     jitterX = Math.random() * jitterR * Math.sin(jitterT);
  24.     jitterY = Math.random() * jitterR * Math.cos(jitterT);
  25.     c.fillStyle = `hsl(${t / Math.PI * 180}deg, 50%, 50%)`;
  26.     c.fillRect(
  27.       SIZE / 2 + r * Math.cos(t) + jitterX,
  28.       SIZE / 2 + r * Math.sin(t) + jitterY, 
  29.       3, 3
  30.     );
  31.   }
  32. }
  33.  
  34. spa(0);
  35. spa(Math.PI);

I made this in response to a question from a friend of mine a few years back…

snippet.zone ~ 2021-22 /// {s/z}