Houdini 19.0 Nodes VOP nodes

Sample Sphere VOP node

Samples the interior or surface of the unit circle, sphere, or hypersphere, within a max angle of a direction.

Since 14.0

The Sample Sphere VOP gives ways to sample either the interior or surface of the unit circle (2D), sphere (3D), or hypersphere (4D), either uniformly, optionally within some angle of a particular direction, or biased toward that direction. The sample is determined by 1, 2, 3, or 4 Uniform Sample values, (depending on how many are needed to parameterize the sample space), between 0 and 1.

In the Orientation Quaternion (4D Direction) case, in order to make generating orientation quaternions within a certain angle of the specified orientation easier, the Maximum Angle from Direction parameter is a quaternion rotation angle, instead of the Euclidean angle in the 4D hypersphere, which would be half as large, and quite confusing.

The Bias Toward Direction, if non-zero, is applied to the axial Uniform Sample component:

u = 1-pow(1-u, 1/(1+powerbias));

Where u is the axial component (the first component for 3D and 4D), and powerbias is the bias.

See also

VOP nodes