D3DXQUATERNION

Describes a quaternion.

typedef struct D3DXQUATERNION {
  FLOAT x, y, z, w;
} D3DXQUATERNION;

Members

x

The x component.

y

The y component.

z

The z component.

w

The w component.

Remarks

Quaternions add a fourth element to the [x, y, z] values that define a vector, resulting in arbitrary 4-D vectors. However, the following 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 CCW rotation about 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)

C++ programmers can take advantage of operator overloading and type casting. The C++ implementation of the D3DXQUATERNION structure implements overloaded constructors and overloaded assignment, unary and binary (including equality) operators. For more information, see C++ Specific Features.

Requirements

  Header: Declared in D3dx8math.h.