Unigine.quat Struct
This class represents a quaternion type. Quaternions represent a rotation. Typically, they are used for smooth interpolation between two angles, and for avoiding the gimbal lock problem that can occur with euler angles.
Quaternions add a fourth element to the [ x, y, z] values that define a vector, resulting in arbitrary 4-D vectors. The following example illustrates how each element of a unit quaternion relates to an axis-angle rotation, where q represents a unit quaternion (x, y, z, w), axis is normalized, and theta is the desired counterclockwise (CCW) rotation around the axis:
- q.x = sin(theta/2) * axis.x
- q.y = sin(theta/2) * axis.y
- q.z = sin(theta/2) * axis.z
- q.w = cos(theta/2)
Usage Example
The following example creates a quaternion for node rotation: 60 degrees per second along Z axis.
Notice
It's supposed that you have already created node instance to rotate.
Source code (C#)
// AppWorldLogic.cs file
public override int update()
{
/* ... */
// get Game instance and delta time value
Game game = Game.get();
float delta_time = game.getIFps();
// create quat for 60 degrees per second rotation along Z axis
quat rotation_delta = new quat(0.0f, 0.0f, 1.0f, 60 * delta_time);
// rotate the node
node.setWorldRotation(node.getWorldRotation() * rotation_delta);
/* ... */
}In the example above, the quaternion was initialized by using four values: 3 axis components (x,y,z) and angle (w component of the quaternion). 1 value of the Z axis component shows that the rotation will be performed along Z axis.
See Also
- An article on Quaternions and Spatial Rotation on Wikipedia.
- A video tutorial on moving and rotating the node by using quaternion (C++)
quat Class
Members
quat()
Default constructor. Produces an identity quaternion (0.0, 0.0, 0.0, 1.0).quat(const quat & q)
Constructor. Initializes the quaternion by copying a given source quaternion.Arguments
- const quat & q - Source quaternion.
quat(const vec3 & axis, float angle)
Constructor. Initializes the quaternion using given rotation axis and angle.Arguments
- const vec3 & axis - Rotation axis.
- float angle - Rotation angle, in degrees.
quat(float angle_x, float angle_y, float angle_z)
Constructor. Initializes the quaternion using given angles for each axis.Arguments
- float angle_x - Rotation angle along the X axis, in degrees.
- float angle_y - Rotation angle along the Y axis, in degrees.
- float angle_z - Rotation angle along the Z axis, in degrees.
quat(const vec3 & col0, const vec3 & col1, const vec3 & col2)
Constructor. Initializes the quaternion using three given matrix columns represented by vec3 vectors.Arguments
- const vec3 & col0 - First matrix column.
- const vec3 & col1 - Second matrix column.
- const vec3 & col2 - Third matrix column.
quat(float x, float y, float z, float angle)
Constructor. Initializes the quaternion using given float values.Arguments
- float x - X component of the quaternion.
- float y - Y component of the quaternion.
- float z - Z component of the quaternion.
- float angle - W component of the quaternion.
explicit quat(const mat4 & m)
Constructor. Initializes the quaternion using a given mat4 source matrix (4x4).Arguments
- const mat4 & m - Source matrix (4x4).
explicit quat(const dmat4 & m)
Constructor. Initializes the quaternion using a given dmat4 source matrix (3x4).Arguments
- const dmat4 & m - Source matrix (3x4).
explicit quat(const float * q)
Constructor. Initializes the vector using a given pointer to the quaternion.Arguments
- const float * q - Pointer to the quaternion.
void set(float x, float y, float z, float angle)
Sets the quaternion by components.Arguments
- float x - X component of the quaternion.
- float y - Y component of the quaternion.
- float z - Z component of the quaternion.
- float angle - W component of the quaternion.
Examples
Source code (UnigineScript)
quat(1.0, 2.0, 3.0, 60);
/*
Creates a quaternion (1.0, 2.0, 3.0, 60)
*/void set(const float * qq)
Sets the quaternion using a given pointer to the source quaternion.Arguments
- const float * qq - Pointer to the source quaternion.
void get(float * qq) const
Gets the quaternion: qq[0]=x, qq[1]=y, qq[2]=z, qq[3]=w.Arguments
- float * qq - Pointer to the quaternion.
float * get()
Returns a pointer to the quaternion.Return value
Pointer to the quaternion.const float * get() const
Returns a constant pointer to the quaternion.Return value
Constant pointer to the quaternion.vec3 getBinormal() const
Returns the quaternion binormal vector with respect to orientation.Return value
Quaternion binormal vector.vec3 getNormal() const
Returns the quaternion normal vector.Return value
Quaternion normal vector.vec3 getTangent() const
Returns the quaternion tangent vector.Return value
Quaternion tangent vector.vec4 getTangent4() const
Returns the quaternion tangent vector and binormal orientation as a four-component vec4 vector.Return value
Four-component vector representing guaternion tangent vector and binormal orientation.float & operator[](int i)
Performs array access to the quaternion item reference by using given item index.Arguments
- int i - Quaternion item index.
Return value
Quaternion item reference.float operator[](int i) const
Performs array access to the quaternion item by using given item index.Arguments
- int i - Quaternion item index.
Return value
Quaternion item.int IDENTITY
Description
Quaternion representing no rotation (0.0, 0.0, 0.0, 1.0).int ZERO
Description
Zero quaternion (0.0, 0.0, 0.0, 0.0).Last update: 2018-08-10
Help improve this article
Was this article helpful?
(or select a word/phrase and press Ctrl+Enter)