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/*
* Copyright 2009, Google Inc.
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are
* met:
*
* * Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* * Redistributions in binary form must reproduce the above
* copyright notice, this list of conditions and the following disclaimer
* in the documentation and/or other materials provided with the
* distribution.
* * Neither the name of Google Inc. nor the names of its
* contributors may be used to endorse or promote products derived from
* this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
* OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
// A shout out to Terrance J. Grant at tatewake.com for his tutorial on arcball
// implementations.
/**
* @fileoverview This file contains functions for implementing an arcball
* calculation. It puts them in the "arcball" module on the o3djs object.
*
* Note: This library is only a sample. It is not meant to be some official
* library. It is provided only as example code.
*
*/
o3djs.provide('o3djs.arcball');
o3djs.require('o3djs.math');
o3djs.require('o3djs.quaternions');
/**
* A Module for arcball manipulation.
*
* This is useful for rotating a model with the mouse.
*
* @namespace
*/
o3djs.arcball = o3djs.arcball || {};
/**
* Creates a new arcball.
* @param {number} areaWidth width of area arcball should cover.
* @param {number} areaHeight height of area arcball should cover.
* @return {!o3djs.arcball.ArcBall} The created arcball.
* @see o3djs.arcball
*/
o3djs.arcball.create = function(areaWidth, areaHeight) {
return new o3djs.arcball.ArcBall(areaWidth, areaHeight);
};
/**
* A class that implements an arcball.
* @constructor
* @param {number} areaWidth width of area arcball should cover.
* @param {number} areaHeight height of area arcball should cover.
* @see o3djs.arcball
*/
o3djs.arcball.ArcBall = function(areaWidth, areaHeight) {
/**
* The start vector.
* @private
* @type {!o3djs.math.Vector3}
*/
this.startVector_ = [0, 0, 0];
/**
* The end vector.
* @private
* @type {!o3djs.math.Vector3}
*/
this.endVector_ = [0, 0, 0];
/**
* The width of the arcBall area.
* @private
* @type {number}
*/
this.areaWidth_ = areaWidth;
/**
* The height of the arcBall area.
* @private
* @type {number}
*/
this.areaHeight_ = areaHeight;
};
/**
* Sets the size of the arcball.
* @param {number} areaWidth width of area arcball should cover.
* @param {number} areaHeight height of area arcball should cover.
*/
o3djs.arcball.ArcBall.prototype.setAreaSize = function(areaWidth, areaHeight) {
this.areaWidth_ = areaWidth;
this.areaHeight_ = areaHeight;
};
/**
* Converts a 2d point to a point on the sphere of radius 1 sphere.
* @param {!o3djs.math.Vector2} newPoint A point in 2d.
* @return {!o3djs.math.Vector3} A point on the sphere of radius 1.
*/
o3djs.arcball.ArcBall.prototype.mapToSphere = function(newPoint) {
// Copy parameter into temp
var tempPoint = o3djs.math.copyVector(newPoint);
// Scale to -1.0 <-> 1.0
tempPoint[0] = tempPoint[0] / this.areaWidth_ * 2.0 - 1.0;
tempPoint[1] = 1.0 - tempPoint[1] / this.areaHeight_ * 2.0;
// Compute square of length from center
var lengthSquared = o3djs.math.lengthSquared(tempPoint);
// If the point is mapped outside of the sphere... (length > radius squared)
if (lengthSquared > 1.0) {
return o3djs.math.normalize(tempPoint).concat(0);
} else {
// Otherwise it's on the inside.
return tempPoint.concat(Math.sqrt(1.0 - lengthSquared));
}
};
/**
* Records the starting point on the sphere.
* @param {!o3djs.math.Vector2} newPoint point in 2d.
*/
o3djs.arcball.ArcBall.prototype.click = function(newPoint) {
this.startVector_ = this.mapToSphere(newPoint);
};
/**
* Computes the rotation of the sphere based on the initial point clicked as
* set through Arcball.click and the current point passed in as newPoint
* @param {!o3djs.math.Vector2} newPoint point in 2d.
* @return {!o3djs.quaternions.Quaternion} A quaternion representing the new
* orientation.
*/
o3djs.arcball.ArcBall.prototype.drag = function(newPoint) {
this.endVector_ = this.mapToSphere(newPoint);
return o3djs.math.cross(this.startVector_, this.endVector_).concat(
o3djs.math.dot(this.startVector_, this.endVector_));
};
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