Added generic graph drawing loop; isolated point drawing of graph style 'Bar'

lib/graph3d/Graph3d.js

@@ -831,21 +831,34 @@ Graph3d.prototype.redraw = function() {
   this._redrawClear();
   this._redrawAxis();
 
-  if (this.style === Graph3d.STYLE.GRID ||
-    this.style === Graph3d.STYLE.SURFACE) {
-    this._redrawDataGrid();
-  }
-  else if (this.style === Graph3d.STYLE.LINE) {
-    this._redrawDataLine();
-  }
-  else if (this.style === Graph3d.STYLE.BAR ||
-    this.style === Graph3d.STYLE.BARCOLOR ||
-    this.style === Graph3d.STYLE.BARSIZE) {
-    this._redrawDataBar();
+  var pointDrawingMethod = undefined;
+  switch (this.style) {
+    case Graph3d.STYLE.BAR:
+      pointDrawingMethod = Graph3d.prototype._redrawBarGraphPoint;
+      break;
   }
-  else {
-    // style is DOT, DOTLINE, DOTCOLOR, DOTSIZE
-    this._redrawDataDot();
+
+  if (pointDrawingMethod !== undefined) {
+    // Use generic drawing loop
+    // Pass the method reference here
+    this._redrawDataGraph(pointDrawingMethod);
+  } else {
+    // Use the old style drawing methods
+
+    if (this.style === Graph3d.STYLE.GRID ||
+      this.style === Graph3d.STYLE.SURFACE) {
+      this._redrawDataGrid();
+    }
+    else if (this.style === Graph3d.STYLE.LINE) {
+      this._redrawDataLine();
+    } else if (this.style === Graph3d.STYLE.BARCOLOR ||
+      this.style === Graph3d.STYLE.BARSIZE) {
+      this._redrawDataBar();
+    }
+    else {
+      // style is DOT, DOTLINE, DOTCOLOR, DOTSIZE
+      this._redrawDataDot();
+    }
   }
 
   this._redrawInfo();
@@ -1563,6 +1576,137 @@ Graph3d.prototype._redrawDataDot = function() {
   }
 };
 
+
+/**
+ * Draw a bar element in the view with the given properties.
+ */
+Graph3d.prototype._redrawBar = function(ctx, point, xWidth, yWidth, color, borderColor) {
+  var i, j, surface, corners;
+
+  // calculate all corner points
+  var me = this;
+  var point3d = point.point;
+  var top = [
+    {point: new Point3d(point3d.x - xWidth, point3d.y - yWidth, point3d.z)},
+    {point: new Point3d(point3d.x + xWidth, point3d.y - yWidth, point3d.z)},
+    {point: new Point3d(point3d.x + xWidth, point3d.y + yWidth, point3d.z)},
+    {point: new Point3d(point3d.x - xWidth, point3d.y + yWidth, point3d.z)}
+  ];
+  var bottom = [
+    {point: new Point3d(point3d.x - xWidth, point3d.y - yWidth, this.zMin)},
+    {point: new Point3d(point3d.x + xWidth, point3d.y - yWidth, this.zMin)},
+    {point: new Point3d(point3d.x + xWidth, point3d.y + yWidth, this.zMin)},
+    {point: new Point3d(point3d.x - xWidth, point3d.y + yWidth, this.zMin)}
+  ];
+
+  // calculate screen location of the points
+  top.forEach(function (obj) {
+    obj.screen = me._convert3Dto2D(obj.point);
+  });
+  bottom.forEach(function (obj) {
+    obj.screen = me._convert3Dto2D(obj.point);
+  });
+
+  // create five sides, calculate both corner points and center points
+  var surfaces = [
+    {corners: top, center: Point3d.avg(bottom[0].point, bottom[2].point)},
+    {corners: [top[0], top[1], bottom[1], bottom[0]], center: Point3d.avg(bottom[1].point, bottom[0].point)},
+    {corners: [top[1], top[2], bottom[2], bottom[1]], center: Point3d.avg(bottom[2].point, bottom[1].point)},
+    {corners: [top[2], top[3], bottom[3], bottom[2]], center: Point3d.avg(bottom[3].point, bottom[2].point)},
+    {corners: [top[3], top[0], bottom[0], bottom[3]], center: Point3d.avg(bottom[0].point, bottom[3].point)}
+  ];
+  point.surfaces = surfaces;
+
+  // calculate the distance of each of the surface centers to the camera
+  for (j = 0; j < surfaces.length; j++) {
+    surface = surfaces[j];
+    var transCenter = this._convertPointToTranslation(surface.center);
+    surface.dist = this.showPerspective ? transCenter.length() : -transCenter.z;
+    // TODO: this dept calculation doesn't work 100% of the cases due to perspective,
+    //     but the current solution is fast/simple and works in 99.9% of all cases
+    //     the issue is visible in example 14, with graph.setCameraPosition({horizontal: 2.97, vertical: 0.5, distance: 0.9})
+  }
+
+  // order the surfaces by their (translated) depth
+  surfaces.sort(function (a, b) {
+    var diff = b.dist - a.dist;
+    if (diff) return diff;
+
+    // if equal depth, sort the top surface last
+    if (a.corners === top) return 1;
+    if (b.corners === top) return -1;
+
+    // both are equal
+    return 0;
+  });
+
+  // draw the ordered surfaces
+  ctx.lineWidth = this._getStrokeWidth(point);
+  ctx.strokeStyle = borderColor;
+  ctx.fillStyle = color;
+  // NOTE: we start at j=2 instead of j=0 as we don't need to draw the two surfaces at the backside
+  for (j = 2; j < surfaces.length; j++) {
+    surface = surfaces[j];
+    corners = surface.corners;
+    ctx.beginPath();
+    ctx.moveTo(corners[3].screen.x, corners[3].screen.y);
+    ctx.lineTo(corners[0].screen.x, corners[0].screen.y);
+    ctx.lineTo(corners[1].screen.x, corners[1].screen.y);
+    ctx.lineTo(corners[2].screen.x, corners[2].screen.y);
+    ctx.lineTo(corners[3].screen.x, corners[3].screen.y);
+    ctx.fill();
+    ctx.stroke();
+  }
+};
+
+
+/**
+ * Draw single datapoint for graph style 'Bar'.
+ */
+Graph3d.prototype._redrawBarGraphPoint = function(ctx, point) {
+  var i, j, surface, corners;
+
+  ctx.lineJoin = 'round';
+  ctx.lineCap = 'round';
+
+  var xWidth = this.xBarWidth / 2;
+  var yWidth = this.yBarWidth / 2;
+
+
+  // determine color
+  var hue, color, borderColor;
+  // calculate Hue from the current value. At zMin the hue is 240, at zMax the hue is 0
+  hue = (1 - (point.point.z - this.zMin) * this.scale.z  / this.verticalRatio) * 240;
+  color = this._hsv2rgb(hue, 1, 1);
+  borderColor = this._hsv2rgb(hue, 1, 0.8);
+
+  this._redrawBar(ctx, point, xWidth, yWidth, color, borderColor);
+};
+
+
+/**
+ * Draw all datapoints for currently selected graph style.
+ *
+ * @param pointDrawMethod - method reference to draw a point in a specific graph style.
+ */
+Graph3d.prototype._redrawDataGraph = function(pointDrawMethod) {
+  var ctx = this._getContext();
+  var i;
+
+  if (this.dataPoints === undefined || this.dataPoints.length <= 0)
+    return;  // TODO: throw exception?
+
+  this._calcTranslations(this.dataPoints);
+
+  for (i = 0; i < this.dataPoints.length; i++) {
+    var point = this.dataPoints[i];
+
+    // Using call() ensures that the correct context is used
+    pointDrawMethod.call(this, ctx, point);
+  }
+};
+
+
 /**
  * Draw all datapoints as bars.
  * This function can be used when the style is 'bar', 'bar-color', or 'bar-size'
@@ -1585,6 +1729,8 @@ Graph3d.prototype._redrawDataBar = function() {
   for (i = 0; i < this.dataPoints.length; i++) {
     var point = this.dataPoints[i];
 
+    // TODO: Remove code for style `Bar` here - it has been refactored to separate routine
+
     // determine color
     var hue, color, borderColor;
     if (this.style === Graph3d.STYLE.BARCOLOR ) {