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title: SphericalHarmonics3 category: Core layout: docs

SphericalHarmonics3

Represents a third-order spherical harmonics (SH). Light probes use this class to encode lighting information.

• Primary reference: https://graphics.stanford.edu/papers/envmap/envmap.pdf
• Secondary reference: https://www.ppsloan.org/publications/StupidSH36.pdf

Constructor

new SphericalHarmonics3()

Constructs a new spherical harmonics.

Properties

.coefficients : Array.<Vector3>

An array holding the (9) SH coefficients.

.isSphericalHarmonics3 : boolean (readonly)

This flag can be used for type testing.

Default is true.

Methods

.add( sh : SphericalHarmonics3 ) : SphericalHarmonics3

Adds the given SH to this instance.

sh | The SH to add.
---|---

Returns: A reference to this spherical harmonics.

.addScaledSH( sh : SphericalHarmonics3, s : number ) : SphericalHarmonics3

A convenience method for performing SphericalHarmonics3#add and SphericalHarmonics3#scale at once.

sh | The SH to add.
---|---
s | The scale factor.

Returns: A reference to this spherical harmonics.

.clone() : SphericalHarmonics3

Returns a new spherical harmonics with copied values from this instance.

Returns: A clone of this instance.

.copy( sh : SphericalHarmonics3 ) : SphericalHarmonics3

Copies the values of the given spherical harmonics to this instance.

sh | The spherical harmonics to copy.
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Returns: A reference to this spherical harmonics.

.equals( sh : SphericalHarmonics3 ) : boolean

Returns true if this spherical harmonics is equal with the given one.

sh | The spherical harmonics to test for equality.
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Returns: Whether this spherical harmonics is equal with the given one.

.fromArray( array : Array.<number>, offset : number ) : SphericalHarmonics3

Sets the SH coefficients of this instance from the given array.

array | An array holding the SH coefficients.
---|---
offset | The array offset where to start copying. Default is 0.

Returns: A clone of this instance.

.getAt( normal : Vector3, target : Vector3 ) : Vector3

Returns the radiance in the direction of the given normal.

normal | The normal vector (assumed to be unit length)
---|---
target | The target vector that is used to store the method's result.

Returns: The radiance.

.getIrradianceAt( normal : Vector3, target : Vector3 ) : Vector3

Returns the irradiance (radiance convolved with cosine lobe) in the direction of the given normal.

normal | The normal vector (assumed to be unit length)
---|---
target | The target vector that is used to store the method's result.

Returns: The irradiance.

.lerp( sh : SphericalHarmonics3, alpha : number ) : SphericalHarmonics3

Linear interpolates between the given SH and this instance by the given alpha factor.

sh | The SH to interpolate with.
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alpha | The alpha factor.

Returns: A reference to this spherical harmonics.

.scale( s : number ) : SphericalHarmonics3

Scales this SH by the given scale factor.

s | The scale factor.
---|---

Returns: A reference to this spherical harmonics.

.set( coefficients : Array.<Vector3> ) : SphericalHarmonics3

Sets the given SH coefficients to this instance by copying the values.

coefficients | The SH coefficients.
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Returns: A reference to this spherical harmonics.

.toArray( array : Array.<number>, offset : number ) : Array.<number>

Returns an array with the SH coefficients, or copies them into the provided array. The coefficients are represented as numbers.

array | The target array. Default is [].
---|---
offset | The array offset where to start copying. Default is 0.

Returns: An array with flat SH coefficients.

.zero() : SphericalHarmonics3

Sets all SH coefficients to 0.

Returns: A reference to this spherical harmonics.

Static Methods

.getBasisAt( normal : Vector3, shBasis : Array.<number> )

Computes the SH basis for the given normal vector.

normal | The normal.
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shBasis | The target array holding the SH basis.

Source

src/math/SphericalHarmonics3.js