cssAudio - Activefile-genericCSS - ActiveGeneric - ActiveHTML - ActiveImage - ActiveJS - ActiveSVG - ActiveText - Activefile-genericVideo - ActiveLovehtmlicon-new-collectionicon-personicon-teamlog-outoctocatpop-outspinnerstartv

Pen Settings

CSS Base

Vendor Prefixing

Add External Stylesheets/Pens

Any URL's added here will be added as <link>s in order, and before the CSS in the editor. If you link to another Pen, it will include the CSS from that Pen. If the preprocessor matches, it will attempt to combine them before processing.

Quick-add: + add another resource

Add External Scripts/Pens

Any URL's added here will be added as <script>s in order, and run before the JavaScript in the editor. You can use the URL of any other Pen and it will include the JavaScript from that Pen.

Quick-add: + add another resource

Code Indentation

     

Save Automatically?

If active, Pens will autosave every 30 seconds after being saved once.

Auto-Updating Preview

If enabled, the preview panel updates automatically as you code. If disabled, use the "Run" button to update.

            
              <!-- Original code here https://gist.github.com/twolfson/687bda8e59b1785d7eb7c9efcb095c54 -->
.container
  p Click and drag a circle to see the our projection and orthogonal vector update!
  svg#scene(width="400", height="400", viewBox="0 0 400 400", xmlns="https://www.w3.org/2000/svg")
    //- DEV: We put our line first so it's hidden behind our vertex z-indicies
    line#line--a-b.line(x1="120", y1="170", x2="280", y2="170",
      stroke-width="10", stroke="#000")
    line#line--a-c.line(x1="60", y1="260", x2="120", y2="170",
      stroke-width="10", stroke="#000")
    line#line--a-c-prime.line(x1="60", y1="170", x2="120", y2="170",
      stroke-width="10", stroke="#F00")
    line#line--c-c-prime.line(x1="60", y1="260", x2="60", y2="170",
      stroke-width="10", stroke="limegreen")
    circle#vertex--a.vertex(cx="120", cy="170", r="20")
    circle#vertex--b.vertex(cx="280", cy="170", r="20")
    circle#vertex--c.vertex(cx="60", cy="260", r="20")
    circle#vertex--c-prime.vertex.vertex--disabled(cx="60", cy="170", r="20")
            
          
!
            
              body {
  /* https://github.com/corysimmons/typographic/blob/2.9.3/scss/typographic.scss#L34 */
  font-family: 'Helvetica Neue', 'Helvetica', 'Arial', 'sans-serif';
}

/* Medium screenshot specific offsets, no height seems to be present */
@media screen and (width: 1024px) {
  .container {
    width: 768px; /* 1024 - 2*(8 - 120 - ~6) -- visual inspection of orange dot in Medium */
    margin: 0 auto;
    padding-top: 51px; /* 43px for Codepen text + 8px gutter width */
  } 
}

#scene {
  border: 1px solid #000;
}

.vertex {
  cursor: pointer;
  stroke: #000;
  stroke-width: 5px;
}
.vertex--disabled {
  cursor: not-allowed;
}

#vertex--a {
  fill: orange;
}
#vertex--b {
  fill: blue;
}
#vertex--c,
#vertex--c-prime {
  fill: limegreen;
}
#vertex--c-prime {
  fill: grey;
  stroke: grey;
}
            
          
!
            
              const Draggabilly = window.Draggabilly;
document.addEventListener('DOMContentLoaded', function handleReady () {
  // Resolve our circle
  // TODO: Add assertion for element resolve
  let sceneEl = document.querySelector('#scene');
  let vertexAEl = sceneEl.querySelector('#vertex--a');
  let vertexBEl = sceneEl.querySelector('#vertex--b');
  let vertexCEl = sceneEl.querySelector('#vertex--c');
  let vertexCPrimeEl = sceneEl.querySelector('#vertex--c-prime');
  let lineABEl = sceneEl.querySelector('#line--a-b');
  let lineACEl = sceneEl.querySelector('#line--a-c');
  let lineACPrimeEl = sceneEl.querySelector('#line--a-c-prime');
  let lineCCPrimeEl = sceneEl.querySelector('#line--c-c-prime');

  // Add our drag bindings
  function bindCircleDraggabilly(circleEl) {
    // Initialize our bindings
    let draggie = new Draggabilly(circleEl);

    // Update our bindings to support SVG
    // https://github.com/desandro/draggabilly/blob/v2.1.1/draggabilly.js#L266
    // https://github.com/desandro/draggabilly/blob/v2.1.1/draggabilly.js#L184-L194
    draggie._getPosition = function() {
      let x = parseFloat(this.element.getAttribute('cx'), 10);
      let y = parseFloat(this.element.getAttribute('cy'), 10);
      // Clean up 'auto' or other non-integer values
      this.position.x = isNaN(x) ? 0 : x;
      this.position.y = isNaN(y) ? 0 : y;
    };
    // https://github.com/desandro/draggabilly/blob/v2.1.1/draggabilly.js#L424-L427
    draggie.positionDrag = function () {
      this.element.setAttribute('cx', this.startPosition.x + this.dragPoint.x);
      this.element.setAttribute('cy', this.startPosition.y + this.dragPoint.y);
    };
    // https://github.com/desandro/draggabilly/blob/v2.1.1/draggabilly.js#L418-L422
    draggie.setLeftTop = function () {
      this.element.setAttribute('cx', this.position.x);
      this.element.setAttribute('cy', this.position.y);
    };

    // Return our overridden binding
    return draggie;
  }
  let vertexADraggie = bindCircleDraggabilly(vertexAEl);
  let vertexBDraggie = bindCircleDraggabilly(vertexBEl);
  let vertexCDraggie = bindCircleDraggabilly(vertexCEl);

  // Eagerly calculate our positions so we can have a shared redraw
  vertexADraggie._getPosition();
  vertexBDraggie._getPosition();
  vertexCDraggie._getPosition();

  // When our vertices move, update our scene
  // DEV: We could be more intelligent about what updated but it's saner to perform a declarative render
  let aVertex = vec2.create();
  let bVertex = vec2.create();
  let cVertex = vec2.create();
  let abVector = vec2.create();
  let acVector = vec2.create();
  let acPrimeVector = vec2.create();
  let ccPrimeVector = vec2.create();
  function updateScene() {
    // Update our lines
    lineABEl.setAttribute('x1', vertexADraggie.position.x);
    lineABEl.setAttribute('y1', vertexADraggie.position.y);
    lineABEl.setAttribute('x2', vertexBDraggie.position.x);
    lineABEl.setAttribute('y2', vertexBDraggie.position.y);
    lineACEl.setAttribute('x1', vertexADraggie.position.x);
    lineACEl.setAttribute('y1', vertexADraggie.position.y);
    lineACEl.setAttribute('x2', vertexCDraggie.position.x);
    lineACEl.setAttribute('y2', vertexCDraggie.position.y);
    lineACPrimeEl.setAttribute('x1', vertexADraggie.position.x);
    lineACPrimeEl.setAttribute('y1', vertexADraggie.position.y);
    lineCCPrimeEl.setAttribute('x1', vertexCDraggie.position.x);
    lineCCPrimeEl.setAttribute('y1', vertexCDraggie.position.y);

    // Unwrap our positions into vectors
    vec2.set(aVertex, vertexADraggie.position.x, vertexADraggie.position.y);
    vec2.set(bVertex, vertexBDraggie.position.x, vertexBDraggie.position.y);
    vec2.set(cVertex, vertexCDraggie.position.x, vertexCDraggie.position.y);
    vec2.sub(abVector, bVertex, aVertex);
    vec2.sub(acVector, cVertex, aVertex);

    // Lay out our mathematical logic
    /*
      axis
      |
      x offshoot
      x/
      origin

      x's = axisProjection (from offshoot)
    */
    // Knowns:
    //   cos(θ) = direction * |axisProjection| / |offshoot|
    //   axisUnitVector = direction * axisProjectionUnitVector
    //   axisUnitVector = axisVector / |axis|
    //   axisProjectionVector = axisProjectionUnitVector * |axisProjection|
    //   dot = |axis||offshoot|cos(θ)
    // Formula:
    //   dot = |axis||offshoot|cos(θ)
    //     = |axis||offshoot|(direction * |axisProjection|/|offshoot|)
    //     = |axis||axisProjection| * direction
    //   Therefore: |axisProjection| = dot/(|axis|*direction)
    //   goal: axisProjectionVector
    //     = axisProjectionUnitVector * |axisProjection|
    //     = direction * axisUnitVector * dot/(|axis| * direction)
    //     = axisVector/|axis| * dot/|axis|
    //     = axisVector * (dot/|axis|^2)

    // Perform our calculation of the projection vector
    // axisVector = abVector
    // offshootVector = acVector
    let abAcDotProduct = vec2.dot(abVector, acVector);
    // DEV: We prefer squared length as there's no square root during calculation so more precision
    let abSquaredLength = vec2.squaredLength(abVector);
    vec2.scale(acPrimeVector, abVector, abAcDotProduct / abSquaredLength);

    // Perform vector addition to find our orthogonal vector
    vec2.sub(ccPrimeVector, acVector, acPrimeVector);

    // Update our line and projection dot
    lineACPrimeEl.setAttribute('x2', aVertex[0] + acPrimeVector[0]);
    lineACPrimeEl.setAttribute('y2', aVertex[1] + acPrimeVector[1]);
    // DEV: We could use `acPrimeVector` but that defeats the point
    lineCCPrimeEl.setAttribute('x2', cVertex[0] - ccPrimeVector[0]);
    lineCCPrimeEl.setAttribute('y2', cVertex[1] - ccPrimeVector[1]);
    vertexCPrimeEl.setAttribute('cx', aVertex[0] + acPrimeVector[0]);
    vertexCPrimeEl.setAttribute('cy', aVertex[1] + acPrimeVector[1]);
  }
  vertexADraggie.on('dragMove', updateScene);
  vertexBDraggie.on('dragMove', updateScene);
  vertexCDraggie.on('dragMove', updateScene);
});

            
          
!
999px
Loading ..................

Console