curves.js

初学者

/*
	Copyright (c) 2004-2006, The Dojo Foundation
	All Rights Reserved.

	Licensed under the Academic Free License version 2.1 or above OR the
	modified BSD license. For more information on Dojo licensing, see:

		http://dojotoolkit.org/community/licensing.shtml
*/



dojo.provide("dojo.math.curves");
dojo.require("dojo.math");
dojo.math.curves = {Line:function (start, end) {
	this.start = start;
	this.end = end;
	this.dimensions = start.length;
	for (var i = 0; i < start.length; i++) {
		start[i] = Number(start[i]);
	}
	for (var i = 0; i < end.length; i++) {
		end[i] = Number(end[i]);
	}
	this.getValue = function (n) {
		var retVal = new Array(this.dimensions);
		for (var i = 0; i < this.dimensions; i++) {
			retVal[i] = ((this.end[i] - this.start[i]) * n) + this.start[i];
		}
		return retVal;
	};
	return this;
}, Bezier:function (pnts) {
	this.getValue = function (step) {
		if (step >= 1) {
			return this.p[this.p.length - 1];
		}
		if (step <= 0) {
			return this.p[0];
		}
		var retVal = new Array(this.p[0].length);
		for (var k = 0; j < this.p[0].length; k++) {
			retVal[k] = 0;
		}
		for (var j = 0; j < this.p[0].length; j++) {
			var C = 0;
			var D = 0;
			for (var i = 0; i < this.p.length; i++) {
				C += this.p[i][j] * this.p[this.p.length - 1][0] * dojo.math.bernstein(step, this.p.length, i);
			}
			for (var l = 0; l < this.p.length; l++) {
				D += this.p[this.p.length - 1][0] * dojo.math.bernstein(step, this.p.length, l);
			}
			retVal[j] = C / D;
		}
		return retVal;
	};
	this.p = pnts;
	return this;
}, CatmullRom:function (pnts, c) {
	this.getValue = function (step) {
		var percent = step * (this.p.length - 1);
		var node = Math.floor(percent);
		var progress = percent - node;
		var i0 = node - 1;
		if (i0 < 0) {
			i0 = 0;
		}
		var i = node;
		var i1 = node + 1;
		if (i1 >= this.p.length) {
			i1 = this.p.length - 1;
		}
		var i2 = node + 2;
		if (i2 >= this.p.length) {
			i2 = this.p.length - 1;
		}
		var u = progress;
		var u2 = progress * progress;
		var u3 = progress * progress * progress;
		var retVal = new Array(this.p[0].length);
		for (var k = 0; k < this.p[0].length; k++) {
			var x1 = (-this.c * this.p[i0][k]) + ((2 - this.c) * this.p[i][k]) + ((this.c - 2) * this.p[i1][k]) + (this.c * this.p[i2][k]);
			var x2 = (2 * this.c * this.p[i0][k]) + ((this.c - 3) * this.p[i][k]) + ((3 - 2 * this.c) * this.p[i1][k]) + (-this.c * this.p[i2][k]);
			var x3 = (-this.c * this.p[i0][k]) + (this.c * this.p[i1][k]);
			var x4 = this.p[i][k];
			retVal[k] = x1 * u3 + x2 * u2 + x3 * u + x4;
		}
		return retVal;
	};
	if (!c) {
		this.c = 0.7;
	} else {
		this.c = c;
	}
	this.p = pnts;
	return this;
}, Arc:function (start, end, ccw) {
	var center = dojo.math.points.midpoint(start, end);
	var sides = dojo.math.points.translate(dojo.math.points.invert(center), start);
	var rad = Math.sqrt(Math.pow(sides[0], 2) + Math.pow(sides[1], 2));
	var theta = dojo.math.radToDeg(Math.atan(sides[1] / sides[0]));
	if (sides[0] < 0) {
		theta -= 90;
	} else {
		theta += 90;
	}
	dojo.math.curves.CenteredArc.call(this, center, rad, theta, theta + (ccw ? -180 : 180));
}, CenteredArc:function (center, radius, start, end) {
	this.center = center;
	this.radius = radius;
	this.start = start || 0;
	this.end = end;
	this.getValue = function (n) {
		var retVal = new Array(2);
		var theta = dojo.math.degToRad(this.start + ((this.end - this.start) * n));
		retVal[0] = this.center[0] + this.radius * Math.sin(theta);
		retVal[1] = this.center[1] - this.radius * Math.cos(theta);
		return retVal;
	};
	return this;
}, Circle:function (center, radius) {
	dojo.math.curves.CenteredArc.call(this, center, radius, 0, 360);
	return this;
}, Path:function () {
	var curves = [];
	var weights = [];
	var ranges = [];
	var totalWeight = 0;
	this.add = function (curve, weight) {
		if (weight < 0) {
			dojo.raise("dojo.math.curves.Path.add: weight cannot be less than 0");
		}
		curves.push(curve);
		weights.push(weight);
		totalWeight += weight;
		computeRanges();
	};
	this.remove = function (curve) {
		for (var i = 0; i < curves.length; i++) {
			if (curves[i] == curve) {
				curves.splice(i, 1);
				totalWeight -= weights.splice(i, 1)[0];
				break;
			}
		}
		computeRanges();
	};
	this.removeAll = function () {
		curves = [];
		weights = [];
		totalWeight = 0;
	};
	this.getValue = function (n) {
		var found = false, value = 0;
		for (var i = 0; i < ranges.length; i++) {
			var r = ranges[i];
			if (n >= r[0] && n < r[1]) {
				var subN = (n - r[0]) / r[2];
				value = curves[i].getValue(subN);
				found = true;
				break;
			}
		}
		if (!found) {
			value = curves[curves.length - 1].getValue(1);
		}
		for (var j = 0; j < i; j++) {
			value = dojo.math.points.translate(value, curves[j].getValue(1));
		}
		return value;
	};
	function computeRanges() {
		var start = 0;
		for (var i = 0; i < weights.length; i++) {
			var end = start + weights[i] / totalWeight;
			var len = end - start;
			ranges[i] = [start, end, len];
			start = end;
		}
	}
	return this;
}};