Quaternion

Introducción

It implements a quaternion. It is implemented from the class bg2e.math.Vec, so it can use all the methods of the Vec class, but modifies the behavior of its constructor, and also adds some methods. This class is used instead of a normal Vec because in this way it is possible to differentiate a quaternion from a four-element vector using the instanceof operator.

import Quat from 'bg2e-js/ts/math/Quat.ts';

The constructor can operate in the following ways:

• No parameters: creates a quaternion initialized to zero.
• Four numeric parameters: creates a quaternion with the parameters specified for alpha, x, y, and z.
• A four-element array: creates a quaternion as above, but specifies the parameters as an array.
• A 9-element array: for example, a Mat3 object, but it could be a standard 9-element array. Initializes the quaternion with a 3x3 rotation matrix.
• A 16-element array: for example, a Mat4 object, but it could be a standard 16-element array. Initializes the quaternion with the rotation matrix extracted from the specified 4x4 transformation matrix.

Methods

initWithMatrix3(m): Loads the quaternion parameters from a 3x3 matrix, that can be specified using an stardard JavaScript array with 9 elements, or using a Mat3 object. Returns this.

initWithMatrix4(m): Loads the quaternion parameters from a 4x4 matrix, that can be specified using an stardard JavaScript array with 16 elements, or using a Mat4 object. Returns this.

initWithValues(alpha,x,y,z): Initialize the quaternion with the alpha, x, y and z and returns this. The parameters are initialized as follows:

quaternion[0] = x * Math.sin( alpha / 2 );
quaternion[1] = y * Math.sin( alpha / 2 );
quaternion[2] = z * Math.sin( alpha / 2 );
quaternion[3] = Math.cos( alpha / 2 );