SphericalHarmonics.EvaluateDirection Method

Language:

Evaluates the spherical harmonic (SH) basis functions from an input direction vector.

Definition

Visual Basic Public Shared Sub EvaluateDirection( _
    ByVal output As GraphicsStream, _
    ByVal order As Integer, _
    ByVal direction As Vector3 _
)

C# public static void EvaluateDirection(
    GraphicsStream output,
    int order,
    Vector3 direction
);

C++ public:
static void EvaluateDirection(
    GraphicsStream^ output,
    int order,
    Vector3 direction
);

JScript public static function EvaluateDirection(
    output : GraphicsStream,
    order : int,
    direction : Vector3
);

Visual Basic	Public Shared Sub EvaluateDirection( _ ByVal output As GraphicsStream, _ ByVal order As Integer, _ ByVal direction As Vector3 _ )
C#	public static void EvaluateDirection( GraphicsStream output, int order, Vector3 direction );
C++	public: static void EvaluateDirection( GraphicsStream^ output, int order, Vector3 direction );
JScript	public static function EvaluateDirection( output : GraphicsStream, order : int, direction : Vector3 );

Parameters

output Microsoft.DirectX.GraphicsStream
SH output coefficients. The basis function Y_lm is stored at location l² + m + l.

order System.Int32
Order of the SH evaluation. Must be in the range of SphericalHarmonics.MinimumOrder to SphericalHarmonics.MaximumOrder, inclusive. The evaluation generates order² coefficients. The degree of the evaluation is order - 1.

direction Microsoft.DirectX.Vector3
(x, y, z) direction vector in which to evaluate the SH basis functions. Must be normalized. See Remarks.

Remarks

Each coefficient of the basis function Y_lm is stored at location l² + m + l, where:

l is the degree of the basis function.

m is the basis function index for the given l value and ranges from -l to l, inclusive.

On the sphere with unit radius as shown, direction can be specified simply with theta, the angle about the z-axis in the right-handed direction, and phi, the angle from z.

The following equations show the relationship between Cartesian (x, y, z) and spherical (theta, phi) coordinates on the unit sphere. The angle theta varies over the range of 0 to 2 pi, while phi varies from 0 to pi.

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output	Microsoft.DirectX.GraphicsStream SH output coefficients. The basis function Y_lm is stored at location l² + m + l.
order	System.Int32 Order of the SH evaluation. Must be in the range of SphericalHarmonics.MinimumOrder to SphericalHarmonics.MaximumOrder, inclusive. The evaluation generates order² coefficients. The degree of the evaluation is order - 1.
direction	Microsoft.DirectX.Vector3 (x, y, z) direction vector in which to evaluate the SH basis functions. Must be normalized. See Remarks.