1 files changed, 188 insertions, 0 deletions
diff --git a/cells1/demo.js b/cells1/demo.js
new file mode 100644
index 0000000..80a8e2d
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+++ b/cells1/demo.js
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+/*global Cell: false, Slider: false, rAF: false */
+
+// -------------------------- demo  -------------------------- //
+
+var canvas, ctx;
+var canvasW, canvasH;
+var slider;
+var cells = [];
+var estimateX = 0;
+var selectedIndex = 0;
+
+var activeAttractor;
+var activeAttractorIndex = 1;
+
+document.addEventListener( 'DOMContentLoaded', init, false );
+
+function init() {
+  canvas = document.querySelector('canvas');
+  ctx = canvas.getContext('2d');
+  // set size
+  canvasW = canvas.width = window.innerWidth - 20;
+  canvasH = canvas.height = 300;
+
+  // create cells
+  var cellWidth = canvasW / 3;
+  for ( var i=0; i < 5; i++ ) {
+    var cell = new Cell({
+      width: cellWidth,
+      height: canvasH - 40,
+      x: ( cellWidth + 40 ) * i,
+      index: i
+    });
+    cells.push( cell );
+  }
+
+  canvas.addEventListener( 'mousedown', onMousedown, false );
+
+  slider = new Slider();
+
+
+  animate();
+}
+
+// -------------------------- animate -------------------------- //
+
+function animate() {
+  if ( !isDragging ) {
+    slider.applyForce( getAttraction() );
+  }
+
+  slider.update();
+
+  render();
+  rAF( animate );
+}
+
+function getAttraction() {
+  var cell = cells[ selectedIndex ];
+  var attractorX = cell.x + cell.width / 2;
+  var distance = -attractorX - slider.x;
+  var force = distance * 0.03;
+  return force;
+}
+
+// -------------------------- render -------------------------- //
+
+function render() {
+  ctx.clearRect( 0, 0, canvasW, canvasH );
+
+  // cursor
+  var cursorX = canvasW / 2;
+  ctx.lineWidth = 1;
+  ctx.strokeStyle = 'hsla(300, 100%, 40%, 1)';
+  ctx.beginPath();
+  ctx.moveTo( cursorX, 0 );
+  ctx.lineTo( cursorX , canvasH );
+  ctx.stroke();
+  ctx.closePath();
+
+  // cells
+  ctx.save();
+  ctx.translate( slider.x + cursorX, 0 );
+  for ( var i=0, len = cells.length; i < len; i++ ) {
+    var cell = cells[i];
+    ctx.fillStyle = 'hsla(0, 100%, 50%, 0.5)';
+    ctx.fillRect( cell.x, 20, cell.width, cell.height );
+    // target line
+    var cellTargetX = cell.x + cell.width / 2;
+    ctx.strokeStyle  = 'yellow';
+    line( cellTargetX, 40, cellTargetX, cell.height );
+  }
+
+  ctx.restore();
+}
+
+function line( x1, y1, x2, y2 ) {
+  ctx.beginPath();
+  ctx.moveTo( x1, y1 );
+  ctx.lineTo( x2, y2 );
+  ctx.stroke();
+  ctx.closePath();
+}
+
+// -------------------------- mouse -------------------------- //
+
+var isDragging = false;
+
+var dragStartX;
+
+function onMousedown( event ) {
+  event.preventDefault();
+  isDragging = true;
+  window.addEventListener( 'mousemove', onMousemove, false );
+  window.addEventListener( 'mouseup', onMouseup, false );
+  dragStartX = event.pageX;
+  slider.dragStartX = slider.x;
+  slider.velocity = 0;
+}
+
+var previousX;
+var previousTime;
+var currentTime;
+
+function onMousemove( event ) {
+  // previous
+  previousX = slider.x;
+  previousTime = currentTime;
+  // current
+  var moveX = event.pageX - dragStartX;
+  slider.x = slider.dragStartX + moveX;
+  currentTime = new Date();
+}
+
+function onMouseup( event ) {
+  dragEnd();
+  // console.log( particle.velocity );
+  window.removeEventListener( 'mousemove', onMousemove, false );
+  window.removeEventListener( 'mousemove', onMouseup, false );
+}
+
+function dragEnd() {
+  if ( previousX ) {
+    // set particle velocity
+    slider.velocity = ( slider.x - previousX ) / ( currentTime - previousTime );
+    slider.velocity *= 1000 / 60;
+    estimateX = slider.getRestingPosition();
+    // reset previousX
+    previousX = null;
+  } else {
+    estimateX = slider.x;
+  }
+
+  // remember this for checking later
+  var prevIndex = selectedIndex;
+
+  // get closest attractor to end position
+  var minDistance = Infinity;
+  var targetX, distance;
+  for ( var i=0, len = cells.length; i < len; i++ ) {
+    var cell = cells[i];
+    targetX = cell.x + cell.width / 2;
+    distance = Math.abs( -estimateX - targetX );
+    if ( distance < minDistance ) {
+      selectedIndex = i;
+      minDistance = distance;
+    }
+  }
+
+  // if not enough velocity to escape current attractor
+  // boost it
+  if ( selectedIndex === prevIndex  ) {
+    var selectedCell = cells[ selectedIndex ];
+    targetX = selectedCell.x + selectedCell.width / 2;
+    distance = -slider.x - targetX;
+    // console.log( ~~distance, ~~slider.velocity );
+    if ( distance > 0 && slider.velocity < -1 && cells[ selectedIndex + 1 ] ) {
+      // if moving towards the right, and positive velocity, and the next attractor
+      selectedIndex++;
+    } else if ( distance < 0 && slider.velocity > 1 && cells[ selectedIndex - 1 ] ) {
+      // if moving towards the left, and negative velocity, and previous attractor
+      selectedIndex--;
+    }
+  }
+
+
+  isDragging = false;
+
+}