SphericalHarmonics3

Functions for 3rd-order Spherical Harmonics (SH), commonly used to represent global irradiance or radiance in real-time.

SH3 is represented as an array of 9 Vec3 coefficients (totaling 27 float values). Each coefficient corresponds to an SH basis function.

Creation

// Create a set of SH3 coefficients (all zeroed)
var sh = sh3_create();

Function	Description
`sh3_create()`	Allocates a new array of 9 Vec3s.
`sh3_set(sh, coefficients)`	Sets the SH coefficients by copying values.
`sh3_zero(sh)`	Sets all SH coefficients to 0.
`sh3_copy(sh, other)`	Copies the values of the given SH to this instance.
`sh3_clone(sh)`	Returns a new SH with copied values from this instance.
`sh3_equals(sh, other)`	Checks if two SH instances are equal.

Function	Description
`sh3_add(sh, other)`	Adds the given SH to this instance.
`sh3_add_scaled_sh(sh, other, s)`	Adds the given SH scaled by s to this instance.
`sh3_scale(sh, s)`	Scales this SH by the given scale factor.
`sh3_lerp(sh, other, alpha)`	Linear interpolates between the given SH and this instance by alpha.

Function	Description
`sh3_from_array(sh, array, offset?)`	Sets the SH coefficients from an array of numbers.
`sh3_to_array(sh, array?, offset?)`	Copies the SH coefficients into an array of numbers.

Function	Returns	Description
`sh3_get_at(sh, normal, target)`	`vec3`	Returns the radiance in the direction of the given normal.
`sh3_get_irradiance_at(sh, normal, target)`	`vec3`	Returns the irradiance in the direction of the given normal.
`sh3_get_basis_at(normal, shBasis)`	`void`	Computes the SH basis for the given normal vector.