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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#

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.

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.
Last update: 2019-08-16
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