continue to play on shader reload if already playing

glsl/raymarching.js

  `
  document.head.appendChild(styleEl);
  
  function TwoTriangles(canvas, fragmentShaderSrc) {
  function TwoTriangles(canvas, fragmentShaderSrc, options) {
    var options = options || {};
    var tt = {};
    tt.canvas = canvas;
    tt.fragmentShaderSrc = fragmentShaderSrc;
      gl.drawArrays(gl.TRIANGLES, 0, 6);
    };
    
    tt.playing = false;
    tt.playing = options.playing || false;
    tt.draw = function(timestamp) {
      if (tt.playing) {
        requestAnimationFrame(tt.draw);
    };
    
    tt.render();
    if (tt.playing) {
      tt.draw();
    }
    return tt;
  }
  
  editor.el.onkeydown = function(ev) {
    try {
      if (ev.ctrlKey && ev.keyCode == 13) {
        tt = TwoTriangles(canvas, editor.el.value);
        tt = TwoTriangles(canvas, editor.el.value, {playing: tt.playing});
        sidebarEl.innerHTML = "";
        sliders = findSliders(tt.fragmentShaderSrc);