m3.js

//source: https://gist.github.com/jannunzi


const m3 = {
    projection: function(width, height) {
      // Note: This matrix flips the Y axis so that 0 is at the top.
      return [
        2 / width, 0, 0,
        0, -2 / height, 0,
        -1, 1, 1
      ];
    },
  
    identity: function() {
      return [
        1, 0, 0,
        0, 1, 0,
        0, 0, 1,
      ];
    },
  
    translation: function(tx, ty) {
      return [
        1, 0, 0,
        0, 1, 0,
        tx, ty, 1,
      ];
    },
  
    rotation: function(angleInRadians) {
      var c = Math.cos(angleInRadians);
      var s = Math.sin(angleInRadians);
      return [
        c,-s, 0,
        s, c, 0,
        0, 0, 1,
      ];
    },
  
    scaling: function(sx, sy) {
      return [
        sx, 0, 0,
        0, sy, 0,
        0, 0, 1,
      ];
    },
  
    multiply: function(a, b) {
      var a00 = a[0 * 3 + 0];
      var a01 = a[0 * 3 + 1];
      var a02 = a[0 * 3 + 2];
      var a10 = a[1 * 3 + 0];
      var a11 = a[1 * 3 + 1];
      var a12 = a[1 * 3 + 2];
      var a20 = a[2 * 3 + 0];
      var a21 = a[2 * 3 + 1];
      var a22 = a[2 * 3 + 2];
      var b00 = b[0 * 3 + 0];
      var b01 = b[0 * 3 + 1];
      var b02 = b[0 * 3 + 2];
      var b10 = b[1 * 3 + 0];
      var b11 = b[1 * 3 + 1];
      var b12 = b[1 * 3 + 2];
      var b20 = b[2 * 3 + 0];
      var b21 = b[2 * 3 + 1];
      var b22 = b[2 * 3 + 2];
      return [
        b00 * a00 + b01 * a10 + b02 * a20,
        b00 * a01 + b01 * a11 + b02 * a21,
        b00 * a02 + b01 * a12 + b02 * a22,
        b10 * a00 + b11 * a10 + b12 * a20,
        b10 * a01 + b11 * a11 + b12 * a21,
        b10 * a02 + b11 * a12 + b12 * a22,
        b20 * a00 + b21 * a10 + b22 * a20,
        b20 * a01 + b21 * a11 + b22 * a21,
        b20 * a02 + b21 * a12 + b22 * a22,
      ];
    },
  
    translate: function(m, tx, ty) {
      return m3.multiply(m, m3.translation(tx, ty));
    },
  
    rotate: function(m, angleInRadians) {
      return m3.multiply(m, m3.rotation(angleInRadians));
    },
  
    scale: function(m, sx, sy) {
      return m3.multiply(m, m3.scaling(sx, sy));
    },
  };