webgl/pointUtil.js

  1. var pointFeature = require('../pointFeature');
  3. /**
  4.  * Extend a point-like feature with additional functions.
  5.  *
  6.  * @param {this} m_this The point-like feature.
  7.  * @param {object} [arg] Feature definition object that might specify the
  8.  *      primitive shape.
  9.  * @memberof geo.webgl
  10.  */
  11. function pointUtil(m_this, arg) {
  12.   arg = arg || {};
  14.   m_this._primitiveShapeAuto = true;
  15.   m_this._primitiveShape = pointFeature.primitiveShapes.auto;
  16.   if (pointFeature.primitiveShapes[arg.primitiveShape] !== undefined) {
  17.     m_this._primitiveShape = arg.primitiveShape;
  18.   }
  19.   m_this._primitiveShapeAuto = m_this._primitiveShape === pointFeature.primitiveShapes.auto;
  20.   if (m_this._primitiveShapeAuto) {
  21.     m_this._primitiveShape = pointFeature.primitiveShapes.sprite;
  22.     m_this._primitiveShapeAuto = true;
  23.   }
  25.   /**
  26.    * Given the current primitive shape and a basic size, return a set of
  27.    * vertices that can be used for a generic point.
  28.    *
  29.    * @param {number} x The base x coordinate.  Usually 0.
  30.    * @param {number} y The base y coordinate.  Usually 0.
  31.    * @param {number} w The base width.  Usually 1.
  32.    * @param {number} h The base height.  Usually 1.
  33.    * @returns {number[]} A flat array of vertices in the form of
  34.    *    `[x0, y0, x1, y1, ...]`.
  35.    */
  36.   m_this._pointPolygon = function (x, y, w, h) {
  37.     var verts;
  38.     switch (m_this._primitiveShape) {
  39.       case pointFeature.primitiveShapes.triangle:
  40.         /* Use an equilateral triangle.  While this has 30% more area than a
  41.          * square, the reduction in vertices should help more than the
  42.          * processing the additional fragments. */
  43.         verts = [
  44.           x, y - h * 2,
  45.           x - w * Math.sqrt(3.0), y + h,
  46.           x + w * Math.sqrt(3.0), y + h
  47.         ];
  48.         break;
  49.       case pointFeature.primitiveShapes.square:
  50.         /* Use a surrounding square split diagonally into two triangles. */
  51.         verts = [
  52.           x - w, y + h,
  53.           x - w, y - h,
  54.           x + w, y + h,
  55.           x - w, y - h,
  56.           x + w, y - h,
  57.           x + w, y + h
  58.         ];
  59.         break;
  60.       default: // sprite
  61.         /* Point sprite uses only one vertex per point. */
  62.         verts = [x, y];
  63.         break;
  64.     }
  65.     return verts;
  66.   };
  68.   /**
  69.    * Return the number of vertices used for each point.
  70.    *
  71.    * @returns {number}
  72.    */
  73.   m_this.verticesPerFeature = function () {
  74.     var unit = m_this._pointPolygon(0, 0, 1, 1);
  75.     return unit.length / 2;
  76.   };
  78.   /**
  79.    * Get or set the primitiveShape.
  80.    *
  81.    * @param {geo.pointFeature.primitiveShapes} [primitiveShape] If specified,
  82.    *   the new primitive shape.
  83.    * @param {boolean} [currentShape] If truthy and getting the shape, return
  84.    *   the shape currently in use if the shape is set to `auto`.  If falsy,
  85.    *   return the specific primitiveShape, which may be `auto`.
  86.    * @returns {geo.pointFeature.primitiveShapes|this} The primitiveShape or
  87.    *   this instance of the feature.
  88.    */
  89.   m_this.primitiveShape = function (primitiveShape, currentShape) {
  90.     if (primitiveShape === undefined) {
  91.       return currentShape || !m_this._primitiveShapeAuto ? m_this._primitiveShape : pointFeature.primitiveShapes.auto;
  92.     }
  93.     if (pointFeature.primitiveShapes[primitiveShape] !== undefined) {
  94.       var update = false;
  95.       if (primitiveShape === pointFeature.primitiveShapes.auto) {
  96.         update = !m_this._primitiveShapeAuto;
  97.         m_this._primitiveShapeAuto = true;
  98.       } else {
  99.         update = m_this._primitiveShapeAuto || m_this._primitiveShape !== primitiveShape;
  100.         m_this._primitiveShapeAuto = false;
  101.         m_this._primitiveShape = primitiveShape;
  102.       }
  103.       if (update) {
  104.         m_this.renderer().contextRenderer().removeActor(m_this.actors()[0]);
  105.         m_this._init(true);
  106.         m_this.dataTime().modified();
  107.       }
  108.     }
  109.     return m_this;
  110.   };
  111. }
  113. module.exports = pointUtil;