/**
* @classdesc A grid class with vertical and horizontal lines.
*
* @requires Vertex
*
* @author Ikaros Kappler
* @date 2018-11-28
* @modified 2018-12-09 Added the utils: baseLog(Number,Number) and mapRasterScale(Number,Number).
* @version 1.0.1
*
* @file Grid
* @fileoverview Note that the PlotBoilerplate already has a Grid instance member. The Grid is not meant
* to be added to the canvas as a drawable as it encapsulates more an abstract concept of the canvas
* rather than a drawable object.
* @public
**/
(function(_context) {
/**
* The constructor.
*
* @constructor
* @name Grid
* @param {Vertex} center - The offset of the grid (default is [0,0]).
* @param {Vertex} size - The x- and y-size of the grid.
**/
var Grid = function( center, size ) {
this.center = center;
this.size = size;
};
/**
* @member {Vertex}
* @memberof Grid
* @instance
*/
Grid.prototype.center = null;
/**
* @member {Vertex}
* @memberof Grid
* @instance
*/
Grid.prototype.size = null;
/**
* @memberof Grid
**/
Grid.utils = {
/**
* Calculate the logarithm of the given number (num) to a given base.<br>
* <br>
* This function returns the number l with<br>
* <pre>num == Math.pow(base,l)</pre>
*
* @member baseLog
* @function
* @memberof Grid
* @inner
* @param {number} base - The base to calculate the logarithm to.
* @param {number} num - The number to calculate the logarithm for.
* @return {number} <pre>log(base)/log(num)</pre>
**/
baseLog : function(base,num) { return Math.log(base) / Math.log(num); },
/**
* Calculate the raster scale for a given logarithmic mapping.<br>
* <br>
* Example (with adjustFactor=2):<br>
* <pre>
* If scale is 4.33, then the mapping is 1/2 (because 2^2 <= 4.33 <= 2^3)<br>
* If scale is 0.33, then the mapping is 2 because (2^(1/2) >= 0.33 >= 2^(1/4)
* </pre>
*
* @member mapRasterScale
* @function
* @memberof Grid
* @inner
* @param {number} adjustFactor The base for the logarithmic raster scaling when zoomed.
* @param {number} scale The currently used scale factor.
* @return {number}
**/
mapRasterScale : function( adjustFactor, scale ) {
var gf = 1.0;
if( scale >= 1 ) {
gf = Math.abs( Math.floor( 1/Grid.utils.baseLog(adjustFactor,scale) ) );
gf = 1 / Math.pow( adjustFactor, gf );
} else {
gf = Math.abs( Math.floor( Grid.utils.baseLog(1/adjustFactor,1/(scale+1)) ) );
//gf = Math.pow( adjustFactor, gf );
}
return gf;
}
};
_context.Grid = Grid;
})(window ? window : module.export );