File: src/shapes/Heightfield.js
var Shape = require('./Shape')
, vec2 = require('../math/vec2')
, Utils = require('../utils/Utils');
module.exports = Heightfield;
/**
* Heightfield shape class. Height data is given as an array. These data points are spread out evenly with a distance "elementWidth".
* @class Heightfield
* @extends Shape
* @constructor
* @param {Array} data An array of Y values that will be used to construct the terrain.
* @param {object} options
* @param {Number} [options.minValue] Minimum value of the data points in the data array. Will be computed automatically if not given.
* @param {Number} [options.maxValue] Maximum value.
* @param {Number} [options.elementWidth=0.1] World spacing between the data points in X direction.
* @todo Should be possible to use along all axes, not just y
*
* @example
* // Generate some height data (y-values).
* var data = [];
* for(var i = 0; i < 1000; i++){
* var y = 0.5 * Math.cos(0.2 * i);
* data.push(y);
* }
*
* // Create the heightfield shape
* var heightfieldShape = new Heightfield(data, {
* elementWidth: 1 // Distance between the data points in X direction
* });
* var heightfieldBody = new Body();
* heightfieldBody.addShape(heightfieldShape);
* world.addBody(heightfieldBody);
*/
function Heightfield(data, options){
options = Utils.defaults(options, {
maxValue : null,
minValue : null,
elementWidth : 0.1
});
if(options.minValue === null || options.maxValue === null){
options.maxValue = data[0];
options.minValue = data[0];
for(var i=0; i !== data.length; i++){
var v = data[i];
if(v > options.maxValue){
options.maxValue = v;
}
if(v < options.minValue){
options.minValue = v;
}
}
}
/**
* An array of numbers, or height values, that are spread out along the x axis.
* @property {array} data
*/
this.data = data;
/**
* Max value of the data
* @property {number} maxValue
*/
this.maxValue = options.maxValue;
/**
* Max value of the data
* @property {number} minValue
*/
this.minValue = options.minValue;
/**
* The width of each element
* @property {number} elementWidth
*/
this.elementWidth = options.elementWidth;
Shape.call(this,Shape.HEIGHTFIELD);
}
Heightfield.prototype = new Shape();
/**
* @method computeMomentOfInertia
* @param {Number} mass
* @return {Number}
*/
Heightfield.prototype.computeMomentOfInertia = function(mass){
return Number.MAX_VALUE;
};
Heightfield.prototype.updateBoundingRadius = function(){
this.boundingRadius = Number.MAX_VALUE;
};
Heightfield.prototype.updateArea = function(){
var data = this.data,
area = 0;
for(var i=0; i<data.length-1; i++){
area += (data[i]+data[i+1]) / 2 * this.elementWidth;
}
this.area = area;
};
/**
* @method computeAABB
* @param {AABB} out The resulting AABB.
* @param {Array} position
* @param {Number} angle
*/
Heightfield.prototype.computeAABB = function(out, position, angle){
// Use the max data rectangle
out.upperBound[0] = this.elementWidth * this.data.length + position[0];
out.upperBound[1] = this.maxValue + position[1];
out.lowerBound[0] = position[0];
out.lowerBound[1] = -Number.MAX_VALUE; // Infinity
};