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SphericalHarmonics.EvaluateDirection Method |
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Evaluates the spherical harmonic (SH) basis functions from an input direction vector.
public static void EvaluateDirection(GraphicsStream, int, Vector3); public static void EvaluateDirection(float[], int, Vector3);
Each coefficient of the basis function Ylm 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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