Class Quaternion

A quaternion is comprised of a scalar component and a 3D vector component. The scalar component is normally referred to as w and the vector might either be referred to as v or a (for axis) or expanded with the individual components: (x, y, z) A full quaternion would then be written as [w (x, y, z)].

Quaternions can be considered to represent an axis and angle pair although sadly these numbers are buried somewhat under some maths...

For the curious you can see here that a given axis (a) and angle (𝜃) pair are represented in a quaternion as follows: |[ [w=cos(𝜃/2) ( x=sin(𝜃/2)*a.x, y=sin(𝜃/2)*a.y, z=sin(𝜃/2)*a.x )]



Unit Quaternions:
When using Quaternions to represent spatial orientations for 3D
graphics it's always assumed you have a unit quaternion. The
magnitude of a quaternion is defined as:
|[
sqrt (w² + x² + y² + z²)

and a unit quaternion satisfies this equation: |[ w² + x² + y² + z² = 1



Thankfully most of the time we don't actually have to worry about
the maths that goes on behind the scenes but if you are curious to
learn more here are some external references:

<itemizedlist>
<listitem>
<ulink url="http://mathworld.wolfram.com/Quaternion.html"/>
</listitem>
<listitem>
<ulink url="http://www.gamedev.net/reference/articles/article1095.asp"/>
</listitem>
<listitem>
<ulink url="http://www.cprogramming.com/tutorial/3d/quaternions.html"/>
</listitem>
<listitem>
<ulink url="http://www.isner.com/tutorials/quatSpells/quaternion_spells_12.htm"/>
</listitem>
<listitem>
3D Maths Primer for Graphics and Game Development ISBN-10: 1556229119
</listitem>
<listitem>
<ulink url="http://www.cs.caltech.edu/courses/cs171/quatut.pdf"/>
</listitem>
<listitem>
<ulink url="http://www.j3d.org/matrix_faq/matrfaq_latest.html#Q56"/>
</listitem>
</itemizedlist>
@record

Hierarchy

Quaternion

Constructors

constructor

new Quaternion(): Cogl.Quaternion

Returns Cogl.Quaternion

Properties

w

w: number

based on the angle of rotation it is cos(𝜃/2)

field

x

x: number

based on the angle of rotation and x component of the axis of rotation it is sin(𝜃/2)*axis.x

field

y

y: number

based on the angle of rotation and y component of the axis of rotation it is sin(𝜃/2)*axis.y

field

z

z: number

based on the angle of rotation and z component of the axis of rotation it is sin(𝜃/2)*axis.z

field

Static name

name: string

Methods

copy

copy(): Cogl.Quaternion

- Defined in @types/Gjs/Cogl-2.0.d.ts:9598
Allocates a new #CoglQuaternion on the stack and initializes it with the same values as src.

Returns Cogl.Quaternion

dot_product

dot_product(b: Cogl.Quaternion): number

- Defined in @types/Gjs/Cogl-2.0.d.ts:9599
Parameters
- b: Cogl.Quaternion
Returns number

free

free(): void

- Defined in @types/Gjs/Cogl-2.0.d.ts:9604
Frees a #CoglQuaternion that was previously allocated via cogl_quaternion_copy().

Returns void

get_rotation_angle

get_rotation_angle(): number

- Defined in @types/Gjs/Cogl-2.0.d.ts:9605
Returns number

get_rotation_axis

get_rotation_axis(): number

- Defined in @types/Gjs/Cogl-2.0.d.ts:9606
Returns number

init

init(angle: number, x: number, y: number, z: number): void

- Defined in @types/Gjs/Cogl-2.0.d.ts:9616
Initializes a quaternion that rotates angle degrees around the axis vector (x, y, z). The axis vector does not need to be normalized.

Parameters
- angle: number
  
  The angle you want to rotate around the given axis
- x: number
  
  The x component of your axis vector about which you want to rotate.
- y: number
  
  The y component of your axis vector about which you want to rotate.
- z: number
  
  The z component of your axis vector about which you want to rotate.
Returns void

init_from_angle_vector

init_from_angle_vector(angle: number, axis3f: number): void

- Defined in @types/Gjs/Cogl-2.0.d.ts:9624
Initializes a quaternion that rotates angle degrees around the given axis vector. The axis vector does not need to be normalized.

Parameters
- angle: number
  
  The angle to rotate around axis3f
- axis3f: number
  
  your 3 component axis vector about which you want to rotate.
Returns void

init_from_array

init_from_array(array: number): void

- Defined in @types/Gjs/Cogl-2.0.d.ts:9630
Initializes a [w (x, y,z)] quaternion directly from an array of 4 floats: [w,x,y,z].

Parameters
- array: number
  
  An array of 4 floats w,(x,y,z)
Returns void

init_from_euler

init_from_euler(euler: Cogl.Euler): void

- Defined in @types/Gjs/Cogl-2.0.d.ts:9631
Parameters
- euler: Cogl.Euler
Returns void

init_from_matrix

init_from_matrix(matrix: Cogl.Matrix): void

- Defined in @types/Gjs/Cogl-2.0.d.ts:9636
Initializes a quaternion from a rotation matrix.

Parameters
- matrix: Cogl.Matrix
  
  A rotation matrix with which to initialize the quaternion
Returns void

init_from_quaternion

init_from_quaternion(src: Cogl.Quaternion): void

- Defined in @types/Gjs/Cogl-2.0.d.ts:9637
Parameters
- src: Cogl.Quaternion
Returns void

init_from_x_rotation

init_from_x_rotation(angle: number): void

- Defined in @types/Gjs/Cogl-2.0.d.ts:9642
XXX: check which direction this rotates

Parameters
- angle: number
  
  The angle to rotate around the x axis
Returns void

init_from_y_rotation

init_from_y_rotation(angle: number): void

- Defined in @types/Gjs/Cogl-2.0.d.ts:9643
Parameters
- angle: number
Returns void

init_from_z_rotation

init_from_z_rotation(angle: number): void

- Defined in @types/Gjs/Cogl-2.0.d.ts:9644
Parameters
- angle: number
Returns void

init_identity

init_identity(): void

- Defined in @types/Gjs/Cogl-2.0.d.ts:9653
Initializes the quaternion with the canonical quaternion identity [1 (0, 0, 0)] which represents no rotation. Multiplying a quaternion with this identity leaves the quaternion unchanged.

You might also want to consider using cogl_get_static_identity_quaternion().

Returns void

invert

invert(): void

- Defined in @types/Gjs/Cogl-2.0.d.ts:9654
Returns void

multiply

multiply(left: Cogl.Quaternion, right: Cogl.Quaternion): void

- Defined in @types/Gjs/Cogl-2.0.d.ts:9667
This combines the rotations of two quaternions into result. The operation is not commutative so the order is important because AxB != BxA. Cogl follows the standard convention for quaternions here so the rotations are applied right to left. This is similar to the combining of matrices.

It is possible to multiply the a quaternion in-place, so result can be equal to a but can't be equal to b.

Parameters
- left: Cogl.Quaternion
  
  The second #CoglQuaternion rotation to apply
- right: Cogl.Quaternion
  
  The first #CoglQuaternion rotation to apply
Returns void

nlerp

nlerp(a: Cogl.Quaternion, b: Cogl.Quaternion, t: number): void

- Defined in @types/Gjs/Cogl-2.0.d.ts:9699
Performs a normalized linear interpolation between two quaternions. That is it does a linear interpolation of the quaternion components and then normalizes the result. This will follow the shortest arc between the two orientations (just like the slerp() function) but will not progress at a constant speed. Unlike slerp() nlerp is commutative which is useful if you are blending animations together. (I.e. nlerp (tmp, a, b) followed by nlerp (result, tmp, d) is the same as nlerp (tmp, a, d) followed by nlerp (result, tmp, b)). Finally nlerp is cheaper than slerp so it can be a good choice if you don't need the constant speed property of the slerp() function.

Notable properties: commutative: Yes constant velocity: No torque minimal (travels along the surface of the 4-sphere): Yes faster than cogl_quaternion_slerp()

Parameters
- a: Cogl.Quaternion
  
  The first #CoglQuaternion
- b: Cogl.Quaternion
  
  The second #CoglQuaternion
- t: number
  
  The factor in the range [0,1] used to interpolate between quaterion a and b.
Returns void

normalize

normalize(): void

- Defined in @types/Gjs/Cogl-2.0.d.ts:9700
Returns void

pow

pow(exponent: number): void

- Defined in @types/Gjs/Cogl-2.0.d.ts:9701
Parameters
- exponent: number
Returns void

slerp

slerp(a: Cogl.Quaternion, b: Cogl.Quaternion, t: number): void

- Defined in @types/Gjs/Cogl-2.0.d.ts:9724
Performs a spherical linear interpolation between two quaternions.

Noteable properties: commutative: No constant velocity: Yes torque minimal (travels along the surface of the 4-sphere): Yes more expensive than cogl_quaternion_nlerp()

Parameters
- a: Cogl.Quaternion
  
  The first #CoglQuaternion
- b: Cogl.Quaternion
  
  The second #CoglQuaternion
- t: number
  
  The factor in the range [0,1] used to interpolate between quaternion a and b.
Returns void

squad

squad(prev: Cogl.Quaternion, a: Cogl.Quaternion, b: Cogl.Quaternion, next: Cogl.Quaternion, t: number): void

- Defined in @types/Gjs/Cogl-2.0.d.ts:9725
Parameters
- prev: Cogl.Quaternion
- a: Cogl.Quaternion
- b: Cogl.Quaternion
- next: Cogl.Quaternion
- t: number
Returns void

Static equal

equal(v1: object, v2: object): number

- Defined in @types/Gjs/Cogl-2.0.d.ts:9807
Compares that all the components of quaternions a and b are equal.

An epsilon value is not used to compare the float components, but the == operator is at least used so that 0 and -0 are considered equal.

Parameters
- v1: object
  
  A #CoglQuaternion
- v2: object
  
  A #CoglQuaternion
Returns number

Hierarchy

Index

Constructors

Properties

Methods

Constructors

constructor

Returns Cogl.Quaternion

Properties

w

x

y

z

Static name

Methods

copy

Returns Cogl.Quaternion

dot_product

Parameters

b: Cogl.Quaternion

Returns number

free

Returns void

get_rotation_angle

Returns number

get_rotation_axis

Returns number

init

Parameters

angle: number

x: number

y: number

z: number

Returns void

init_from_angle_vector

Parameters

angle: number

axis3f: number

Returns void

init_from_array

Parameters

array: number

Returns void

init_from_euler

Parameters

euler: Cogl.Euler

Returns void

init_from_matrix

Parameters

matrix: Cogl.Matrix

Returns void

init_from_quaternion

Parameters

src: Cogl.Quaternion

Returns void

init_from_x_rotation

Parameters

angle: number

Returns void

init_from_y_rotation

Parameters

angle: number

Returns void

init_from_z_rotation

Parameters

angle: number

Returns void

init_identity

Returns void

invert

Returns void

multiply

Parameters

left: Cogl.Quaternion

right: Cogl.Quaternion

Returns void

nlerp

Parameters

a: Cogl.Quaternion

b: Cogl.Quaternion