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Microsoft DirectX 9.0 |

Describes a quaternion.

Syntax

typedef struct D3DXQUATERNION { FLOAT x; FLOAT y; FLOAT z; FLOAT 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 (whereqrepresents a unit quaternion (x, y, z, w),axisis normalized, andthetais 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 with the D3DXQUATERNION Extensions, which implement overloaded constructors, assignment, unary, and binary (including equality) operators.

Structure Information

Header d3dx9math.h Minimum operating systems Windows 98