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SphericalHarmonics.EvaluateHemisphereLight Method |
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Evaluates a light that is a linear interpolation between two colors over the sphere.
The interpolation is done linearly between the two points, not over the surface of the sphere (that is, if the axis were (0,0,1), it is linear in Z, not in the azimuthal angle). The resulting spherical lighting function is normalized so that a point on a perfectly diffuse surface with no shadowing and a normal pointed towards direction would result in exit radiance with a value of 1 (if the top color were white and the bottom color were black). This is a very simple model where top represents the intensity of the "sky" and bottom represents the intensity of the "ground".
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.
Exceptions
InvalidCallException The method call is invalid. For example, a method's parameter might contain an invalid value.
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