webgl/lookupTable2D.js

  1. var inherit = require('../inherit');
  2. var timestamp = require('../timestamp');
  3. var vgl = require('../vgl');
  5. /**
  6.  * Switch to a specific texture unit.
  7.  *
  8.  * @param {vgl.renderState} renderState An object that contains the context
  9.  *   used for drawing.
  10.  * @param {number} textureUnit The number of the texture unit [0-15].
  11.  * @private
  12.  */
  13. function activateTextureUnit(renderState, textureUnit) {
  14.   if (textureUnit >= 0 && textureUnit <= 31) {
  15.     renderState.m_context.activeTexture(vgl.GL.TEXTURE0 + textureUnit);
  16.   } else {
  17.     throw Error('[error] Texture unit ' + textureUnit + ' is not supported');
  18.   }
  19. }
  21. /**
  22.  * Create a new instance of class webgl_lookupTable2D.
  23.  *
  24.  * @class
  25.  * @alias geo.webgl.lookupTable2D
  26.  * @param {object} arg Options object.
  27.  * @param {number} [arg.maxWidth] Maximum width to use for the texture.  If the
  28.  *   number of colors set is less than this, the texture is 1D.  If greater, it
  29.  *   will be a rectangle of maxWidth x whatever height is necessary.
  30.  * @param {number[]} [arg.colorTable] Initial color table for the texture.
  31.  *   This is of the form RGBARGBA... where each value is an integer on the
  32.  *   scale [0,255].
  33.  * @extends vgl.texture
  34.  * @returns {geo.webgl.lookupTable2D}
  35.  */
  36. var webgl_lookupTable2D = function (arg) {
  37.   'use strict';
  39.   if (!(this instanceof webgl_lookupTable2D)) {
  40.     return new webgl_lookupTable2D(arg);
  41.   }
  42.   arg = arg || {};
  43.   vgl.texture.call(this);
  45.   var m_setupTimestamp = timestamp(),
  46.       m_maxWidth = arg.maxWidth || 4096,
  47.       m_colorTable = new Uint8Array([0, 0, 0, 0]),
  48.       m_colorTableOrig,
  49.       m_this = this;
  51.   /**
  52.    * Create lookup table, initialize parameters, and bind data to it.
  53.    *
  54.    * @param {vgl.renderState} renderState An object that contains the context
  55.    *   used for drawing.
  56.    */
  57.   this.setup = function (renderState) {
  58.     activateTextureUnit(renderState, m_this.textureUnit());
  60.     renderState.m_context.deleteTexture(m_this.m_textureHandle);
  61.     m_this.m_textureHandle = renderState.m_context.createTexture();
  62.     renderState.m_context.bindTexture(vgl.GL.TEXTURE_2D, m_this.m_textureHandle);
  63.     renderState.m_context.texParameteri(vgl.GL.TEXTURE_2D, vgl.GL.TEXTURE_MIN_FILTER, vgl.GL.NEAREST);
  64.     renderState.m_context.texParameteri(vgl.GL.TEXTURE_2D, vgl.GL.TEXTURE_MAG_FILTER, vgl.GL.NEAREST);
  65.     renderState.m_context.texParameteri(vgl.GL.TEXTURE_2D, vgl.GL.TEXTURE_WRAP_S, vgl.GL.CLAMP_TO_EDGE);
  66.     renderState.m_context.texParameteri(vgl.GL.TEXTURE_2D, vgl.GL.TEXTURE_WRAP_T, vgl.GL.CLAMP_TO_EDGE);
  67.     renderState.m_context.pixelStorei(vgl.GL.UNPACK_ALIGNMENT, 1);
  68.     renderState.m_context.pixelStorei(vgl.GL.UNPACK_FLIP_Y_WEBGL, true);
  70.     renderState.m_context.texImage2D(
  71.       vgl.GL.TEXTURE_2D, 0, vgl.GL.RGBA, m_this.width, m_this.height, 0,
  72.       vgl.GL.RGBA, vgl.GL.UNSIGNED_BYTE, m_colorTable);
  74.     renderState.m_context.bindTexture(vgl.GL.TEXTURE_2D, null);
  75.     m_setupTimestamp.modified();
  76.   };
  78.   /**
  79.    * Get/set color table.
  80.    *
  81.    * @param {number[]} [val] An array of RGBARGBA... integers on a scale
  82.    *   of [0, 255].  `undefined` to get the current value.
  83.    * @returns {number[]|this}
  84.    */
  85.   this.colorTable = function (val) {
  86.     if (val === undefined) {
  87.       return m_colorTableOrig;
  88.     }
  89.     m_colorTableOrig = val;
  90.     if (val.length < 4) {
  91.       val = [0, 0, 0, 0];
  92.     }
  93.     m_this.width = Math.min(m_maxWidth, val.length / 4);
  94.     m_this.height = Math.ceil(val.length / 4 / m_maxWidth);
  95.     if (!(val instanceof Uint8Array) || val.length !== m_this.width * m_this.height * 4) {
  96.       if (val.length < m_this.width * m_this.height * 4) {
  97.         val = val.concat(new Array(m_this.width * m_this.height * 4 - val.length).fill(0));
  98.       }
  99.       m_colorTable = new Uint8Array(val);
  100.     } else {
  101.       m_colorTable = val;
  102.     }
  103.     m_this.modified();
  104.     return m_this;
  105.   };
  107.   /**
  108.    * Get maxWidth value.
  109.    *
  110.    * @returns {number} The maxWidth of the texture used.
  111.    */
  112.   this.maxWidth = function () {
  113.     return m_maxWidth;
  114.   };
  116.   this.colorTable(arg.colorTable || []);
  118.   return this;
  119. };
  121. inherit(webgl_lookupTable2D, vgl.texture);
  123. module.exports = webgl_lookupTable2D;