CodePen Embed - B-spline

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 \\n  display: block;\\n}\",\"js\":\"var obj = document.getElementById('drawing');\\nvar ctx = obj.getContext('2d');\\nvar Idint;\\nvar points = [];\\nvar legendPoints = [];\\nvar pointsDel = false;\\n\\naddEventListener(\\\"mousedown\\\", mDown);\\naddEventListener(\\\"mouseup\\\", mUp);\\naddEventListener(\\\"mousemove\\\", mMove);\\n\\n\\nfunction deletePoints(){\\n  points = new Array();\\n  legendPoints = new Array();\\n}\\n\\nfunction deletePoint(ind){\\n  points.splice(ind, 1);\\n  for(let i = ind; i < points.length; i++){\\n    points[i].legend = \\\"P\\\" + String(i);    \\n  }\\n}\\n\\nfunction deletePointCheck(){\\n  pointsDel = !pointsDel;\\n}\\n\\nfunction addPoint(x, y){\\n  if(x >=0 && x <= obj.width && y >=0 && y<= obj.height) points.push(new Point(x, y, \\\"P\\\" + String(points.length)));\\n}\\n\\nvar mouseDownOnPoint = false;\\nvar mouseDown = false;\\nvar dragPoint = 0;\\nfunction mDown(event){\\n  mouseDown = true;\\n  let rect = obj.getBoundingClientRect();\\n  let x = event.clientX - rect.left;\\n  let y = event.clientY - rect.top;\\n  for(let i = 0; i < points.length; i++){\\n    if(x >= points[i].x - points[i].r && x <= points[i].x + points[i].r && y >= points[i].y - points[i].r && y <= points[i].y + points[i].r){\\n      points[i].x = x; points[i].y = y; dragPoint = i;\\n      if(pointsDel) { deletePoint(i); return; }\\n      mouseDownOnPoint = true;\\n    }\\n  }\\n  if(!mouseDownOnPoint && !pointsDel) addPoint(x, y);\\n}\\nfunction mUp(event){\\n  mouseDown = false;\\n  mouseDownOnPoint = false;\\n}\\n\\nfunction mMove(event){\\n  if(mouseDown){\\n    if(pointsDel) return;\\n    if(mouseDownOnPoint){\\n      let rect = obj.getBoundingClientRect();\\n      let x = event.clientX - rect.left;\\n      let y = event.clientY - rect.top;\\n      let ind = dragPoint;\\n      if(x < points[ind].r) x = points[ind].r;\\n      if(x > obj.width - points[ind].r) x = obj.width - points[ind].r;\\n      if(y < points[ind].r) y = points[ind].r;\\n      if(y > obj.height - points[ind].r) y = obj.height - points[ind].r;\\n      points[ind].x = x; points[ind].y = y;\\n    }\\n  }\\n}\\n\\nfunction sin(deg){\\n  return Math.sin(deg * Math.PI / 180);\\n}\\nfunction cos(deg){\\n  return Math.cos(deg * Math.PI / 180);\\n}\\n\\nfunction circle(x, y, r, color = \\\"white\\\"){\\n  let oldColor = ctx.fillStyle;\\n  ctx.beginPath();\\n  ctx.moveTo(x, y + r);\\n  for(let t = 0; t <= 360; t += 1){\\n    ctx.lineTo(r * sin(t) + x, r * cos(t) + y);\\n  }\\n  ctx.fillStyle = color; ctx.fill();\\n  ctx.stroke();\\n  ctx.fillStyle = oldColor;\\n}\\n\\nclass Point{\\n  x = 0; y = 0; legend;\\n  r = 5; color; fontSize;\\n  \\n  constructor(x = 0, y = 0, legend = \\\"\\\", color = \\\"black\\\", r = 5, fontSize = 14){\\n    this.x = x; this.y = y; this.r = r;\\n    this.legend = legend; this.fontSize = fontSize\\n    this.color = color;\\n  }\\n  \\n  copyFrom(point){\\n    this.x = point.x; this.y = point.y;\\n    this.r = point.r; this.color = point.color;\\n    this.legend = point.legend; this.fontSize = point.fontSize;\\n  }\\n  \\n  draw(fillColor = \\\"white\\\"){\\n    ctx.beginPath();\\n    ctx.srokeStyle = \\\"white\\\";\\n    circle(this.x, this.y, this.r, \\\"white\\\")\\n    ctx.strokeStyle = this.color;\\n    circle(this.x, this.y, this.r, fillColor)\\n    ctx.fillStyle = this.color;\\n    ctx.font = String(this.fontSize) + 'px sherif';\\n    ctx.fillText(this.legend, this.x - this.r - 2, this.y - this.r - 2);\\n  }\\n}\\n\\nfunction betaSpline(points, color = \\\"black\\\"){\\n  let oldStrokeStyle = ctx.strokeStyle;\\n  ctx.beginPath();\\n  legendPoints = [];\\n  for(let i = 1; i < points.length - 2; i++){\\n    let a3 = (-points[i-1].x + 3*points[i].x - 3*points[i+1].x + points[i+2].x) / 6,\\n        a2 = (points[i-1].x - 2*points[i].x + points[i+1].x) / 2,\\n        a1 = (-points[i-1].x + points[i+1].x) / 2,\\n        a0 = (points[i-1].x + 4*points[i].x + points[i+1].x) / 6;\\n    let b3 = (-points[i-1].y + 3*points[i].y - 3*points[i+1].y + points[i+2].y) / 6,\\n        b2 = (points[i-1].y - 2*points[i].y + points[i+1].y) / 2,\\n        b1 = (-points[i-1].y + points[i+1].y) / 2,\\n        b0 = (points[i-1].y + 4*points[i].y + points[i+1].y) / 6;    \\n \\n    ctx.fillStyle = \\\"blue\\\";\\n    ctx.font = '12px sherif';    \\n    ctx.fillText(\\\"Q\\\" + String(i+2), a0 + 0.5*(a1 + 0.5*(a2 + 0.5*a3)) - 2, b0 + 0.5*(b1 + 0.5*(b2 + 0.5*b3)) - 2);\\n    legendPoints.push(new Point(a0, b0, \\\"t\\\" + String(i+2), \\\"black\\\", 3, 12));\\n    if(i + 3 == points.length) legendPoints.push(new Point(a0 + a1 + a2 + a3, b0 + b1 + b2 + b3, \\\"t\\\" + String(i+3), \\\"black\\\", 3, 12));\\n    \\n    for(let t = 0; t <= 1; t += 0.005){\\n      let x = ((a3 * t + a2) * t + a1) * t + a0;\\n      let y = ((b3 * t + b2) * t + b1) * t + b0;\\n      ctx.lineTo(x, y);\\n    }\\n  }\\n  ctx.strokeStyle = color;\\n  ctx.stroke();\\n  ctx.strokeStyle = oldStrokeStyle;\\n}\\n\\nfunction clear(){\\n  ctx.fillStyle = \\\"white\\\";\\n  ctx.fillRect(0,0,ctx.canvas.width, ctx.canvas.height);\\n}\\n\\nfunction init(){\\n  clear();\\n  betaSpline(points, \\\"red\\\");\\n  for(let i = 0; i < points.length; i++) points[i].draw();\\n  for(let i = 0; i < legendPoints.length; i++) legendPoints[i].draw(\\\"black\\\");\\n  Idint = requestAnimationFrame(init);\\n}\\n\\nfunction main(){\\n  deletePoints();\\n  addPoint(80, 240);\\n  addPoint(80, 100);\\n  addPoint(230, 115);\\n  addPoint(225, 260);\\n  addPoint(385, 240);\\n  addPoint(450, 100);\\n  addPoint(555, 111);\\n  addPoint(570, 240);\\n  init();\\n}\\n\\nmain();\",\"html_pre_processor\":\"none\",\"css_pre_processor\":\"none\",\"js_pre_processor\":\"none\",\"html_classes\":\"\",\"css_starter\":\"neither\",\"js_library\":null,\"created_at\":\"2023-01-10T07:34:45.578Z\",\"updated_at\":\"2023-01-10T15:02:34.623Z\",\"title\":\"B-spline\",\"description\":\"\",\"slug_hash\":\"mdjWmej\",\"head\":\"\",\"private\":false,\"has_animation\":true,\"team_id\":0,\"css_prefix\":\"neither\",\"template\":false,\"parent_id\":0,\"comments_count\":0,\"custom_screenshot_filename\":null,\"loves_count\":0,\"pick\":false,\"popularity\":2,\"views_count\":24,\"pick_visible_at\":null,\"cpid\":\"01859a9a-5c4a-7caf-b4fd-e8abb4691c46\",\"is_new_editor_pen\":false,\"access\":\"Public\",\"pen_hash\":null}","__processorsMap":{"autoprefixer":"autoprefixer-10","babel":"babel-7","coffeescript":"coffeescript-2","format-1":"format-1","flutter":"flutter-1","haml":"haml-4","less":"less-3","lint-1":"lint-1","livescript":"livescript-1","markdown":"markdown-11","postcss":"postcss-7","pug":"pug-2","sass":"sass-1","scss":"sass-1","sass-ruby-3":"sass-ruby-3","sass-ruby-compass-3":"sass-ruby-compass-3","slim":"slim-3","stylus":"stylus-0","typescript":"typescript-4","vue":"vue-2","vue3":"vue-3"},"__favicon_mask_icon":"https://cpwebassets.codepen.io/assets/favicon/logo-pin-b4b4269c16397ad2f0f7a01bcdf513a1994f4c94b8af2f191c09eb0d601762b1.svg","__favicon_shortcut_icon":"https://cpwebassets.codepen.io/assets/favicon/favicon-aec34940fbc1a6e787974dcd360f2c6b63348d4b1f4e06c77743096d55480f33.ico","__path_to_iframe_console_runner":"https://cpwebassets.codepen.io/assets/editor/iframe/iframeConsoleRunner-6d8bf8b4b479137260842506acbb12717dace0823c023e08b96360e60b0840d9.js","__path_to_iframe_refresh_css":"https://cpwebassets.codepen.io/assets/editor/iframe/iframeRefreshCSS-44fe83e49b63affec96918c9af88c0d80b209a862cf87ac46bc933074b8c557d.js","__path_to_iframe_runtime_errors":"https://cpwebassets.codepen.io/assets/editor/iframe/iframeRuntimeErrors-4f205f2c14e769b448bcf477de2938c681660d5038bc464e3700256713ebe261.js","__path_to_processor_worker":"https://cpwebassets.codepen.io/assets/packs/router.js","__path_to_stop_execution_on_timeout":"https://cpwebassets.codepen.io/assets/common/stopExecutionOnTimeout-2c7831bb44f98c1391d6a4ffda0e1fd302503391ca806e7fcc7b9b87197aec26.js","__pen_normalize_css_url":"https://public.codepenassets.com/css/normalize-5.0.0.min.css","__pen_prefix_free_url":"https://public.codepenassets.com/js/prefixfree-1.0.7.min.js","__pen_reset_css_url":"https://public.codepenassets.com/css/reset-2.0.min.css"}