public sealed class Quaternion : IMessage<Quaternion>, IEquatable<Quaternion>, IDeepCloneable<Quaternion>, IBufferMessage, IMessage
A quaternion is defined as the quotient of two directed lines in a three-dimensional space or equivalently as the quotient of two Euclidean vectors (https://en.wikipedia.org/wiki/Quaternion).
Quaternions are often used in calculations involving three-dimensional rotations (https://en.wikipedia.org/wiki/Quaternions_and_spatial_rotation), as they provide greater mathematical robustness by avoiding the gimbal lock problems that can be encountered when using Euler angles (https://en.wikipedia.org/wiki/Gimbal_lock).
Quaternions are generally represented in this form:
w + xi + yj + zk
where x, y, z, and w are real numbers, and i, j, and k are three imaginary numbers.
Our naming choice (x, y, z, w)
comes from the desire to avoid confusion for
those interested in the geometric properties of the quaternion in the 3D
Cartesian space. Other texts often use alternative names or subscripts, such
as (a, b, c, d)
, (1, i, j, k)
, or (0, 1, 2, 3)
, which are perhaps
better suited for mathematical interpretations.
To avoid any confusion, as well as to maintain compatibility with a large
number of software libraries, the quaternions represented using the protocol
buffer below must follow the Hamilton convention, which defines ij = k
(i.e. a right-handed algebra), and therefore:
i^2 = j^2 = k^2 = ijk = −1
ij = −ji = k
jk = −kj = i
ki = −ik = j
Please DO NOT use this to represent quaternions that follow the JPL convention, or any of the other quaternion flavors out there.
Definitions:
- Quaternion norm (or magnitude):
sqrt(x^2 + y^2 + z^2 + w^2)
. - Unit (or normalized) quaternion: a quaternion whose norm is 1.
- Pure quaternion: a quaternion whose scalar component (
w
) is 0. - Rotation quaternion: a unit quaternion used to represent rotation.
- Orientation quaternion: a unit quaternion used to represent orientation.
A quaternion can be normalized by dividing it by its norm. The resulting quaternion maintains the same direction, but has a norm of 1, i.e. it moves on the unit sphere. This is generally necessary for rotation and orientation quaternions, to avoid rounding errors: https://en.wikipedia.org/wiki/Rotation_formalisms_in_three_dimensions
Note that (x, y, z, w)
and (-x, -y, -z, -w)
represent the same rotation,
but normalization would be even more useful, e.g. for comparison purposes, if
it would produce a unique representation. It is thus recommended that w
be
kept positive, which can be achieved by changing all the signs when w
is
negative.
Implements
IMessageQuaternion, IEquatableQuaternion, IDeepCloneableQuaternion, IBufferMessage, IMessageNamespace
Google.TypeAssembly
Google.Api.CommonProtos.dll
Constructors
Quaternion()
public Quaternion()
Quaternion(Quaternion)
public Quaternion(Quaternion other)
Parameter | |
---|---|
Name | Description |
other |
Quaternion |
Fields
WFieldNumber
public const int WFieldNumber = 4
Field number for the "w" field.
Field Value | |
---|---|
Type | Description |
int |
XFieldNumber
public const int XFieldNumber = 1
Field number for the "x" field.
Field Value | |
---|---|
Type | Description |
int |
YFieldNumber
public const int YFieldNumber = 2
Field number for the "y" field.
Field Value | |
---|---|
Type | Description |
int |
ZFieldNumber
public const int ZFieldNumber = 3
Field number for the "z" field.
Field Value | |
---|---|
Type | Description |
int |
Properties
Descriptor
public static MessageDescriptor Descriptor { get; }
Property Value | |
---|---|
Type | Description |
MessageDescriptor |
Parser
public static MessageParser<Quaternion> Parser { get; }
Property Value | |
---|---|
Type | Description |
MessageParserQuaternion |
W
public double W { get; set; }
The scalar component.
Property Value | |
---|---|
Type | Description |
double |
X
public double X { get; set; }
The x component.
Property Value | |
---|---|
Type | Description |
double |
Y
public double Y { get; set; }
The y component.
Property Value | |
---|---|
Type | Description |
double |
Z
public double Z { get; set; }
The z component.
Property Value | |
---|---|
Type | Description |
double |
Methods
CalculateSize()
public int CalculateSize()
Calculates the size of this message in Protocol Buffer wire format, in bytes.
Returns | |
---|---|
Type | Description |
int |
The number of bytes required to write this message to a coded output stream. |
Clone()
public Quaternion Clone()
Creates a deep clone of this object.
Returns | |
---|---|
Type | Description |
Quaternion |
A deep clone of this object. |
Equals(Quaternion)
public bool Equals(Quaternion other)
Parameter | |
---|---|
Name | Description |
other |
Quaternion |
Returns | |
---|---|
Type | Description |
bool |
Equals(object)
public override bool Equals(object other)
Parameter | |
---|---|
Name | Description |
other |
object |
Returns | |
---|---|
Type | Description |
bool |
GetHashCode()
public override int GetHashCode()
Returns | |
---|---|
Type | Description |
int |
MergeFrom(CodedInputStream)
public void MergeFrom(CodedInputStream input)
Merges the data from the specified coded input stream with the current message.
Parameter | |
---|---|
Name | Description |
input |
CodedInputStream |
See the user guide for precise merge semantics.
MergeFrom(Quaternion)
public void MergeFrom(Quaternion other)
Merges the given message into this one.
Parameter | |
---|---|
Name | Description |
other |
Quaternion |
See the user guide for precise merge semantics.
ToString()
public override string ToString()
Returns | |
---|---|
Type | Description |
string |
WriteTo(CodedOutputStream)
public void WriteTo(CodedOutputStream output)
Writes the data to the given coded output stream.
Parameter | |
---|---|
Name | Description |
output |
CodedOutputStream Coded output stream to write the data to. Must not be null. |