-
-
Notifications
You must be signed in to change notification settings - Fork 35.3k
Commit
This commit does not belong to any branch on this repository, and may belong to a fork outside of the repository.
Merge pull request #16187 from WestLangley/dev-sh3
Added spherical harmonics class
- Loading branch information
Showing
1 changed file
with
211 additions
and
0 deletions.
There are no files selected for viewing
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
Original file line number | Diff line number | Diff line change |
---|---|---|
@@ -0,0 +1,211 @@ | ||
import { Vector3 } from './Vector3.js'; | ||
|
||
/** | ||
* @author bhouston / http://clara.io | ||
* @author WestLangley / http:/WestLangley | ||
* | ||
* Primary reference: | ||
* https://graphics.stanford.edu/papers/envmap/envmap.pdf | ||
* | ||
* Secondary reference: | ||
* https://www.ppsloan.org/publications/StupidSH36.pdf | ||
*/ | ||
|
||
// 3-band SH defined by 9 coefficients | ||
|
||
function SphericalHarmonics3() { | ||
|
||
this.coefficients = []; | ||
|
||
for ( var i = 0; i < 9; i ++ ) { | ||
|
||
this.coefficients.push( new Vector3() ); | ||
|
||
} | ||
|
||
} | ||
|
||
Object.assign( SphericalHarmonics3.prototype, { | ||
|
||
isSphericalHarmonics3: true, | ||
|
||
set: function ( coefficients ) { | ||
|
||
for ( var i = 0; i < 9; i ++ ) { | ||
|
||
this.coefficients[ i ].copy( coefficients[ i ] ); | ||
|
||
} | ||
|
||
return this; | ||
|
||
}, | ||
|
||
zero: function () { | ||
|
||
for ( var i = 0; i < 9; i ++ ) { | ||
|
||
this.coefficients[ i ].set( 0, 0, 0 ); | ||
|
||
} | ||
|
||
return this; | ||
|
||
}, | ||
|
||
// get the radiance in the direction of the normal | ||
// target is a Vector3 | ||
getAt: function ( normal, target ) { | ||
|
||
// normal is assumed to be unit length | ||
|
||
var x = normal.x, y = normal.y, z = normal.z; | ||
|
||
var coeff = this.coefficients; | ||
|
||
// band 0 | ||
target = coeff[ 0 ] * 0.282095; | ||
|
||
// band 1 | ||
target += coeff[ 1 ] * 0.488603 * y; | ||
target += coeff[ 2 ] * 0.488603 * z; | ||
target += coeff[ 3 ] * 0.488603 * x; | ||
|
||
// band 2 | ||
target += coeff[ 4 ] * 1.092548 * ( x * y ); | ||
target += coeff[ 5 ] * 1.092548 * ( y * z ); | ||
target += coeff[ 6 ] * 0.315392 * ( 3.0 * z * z - 1.0 ); | ||
target += coeff[ 7 ] * 1.092548 * ( x * z ); | ||
target += coeff[ 8 ] * 0.546274 * ( x * x - y * y ); | ||
|
||
return target; | ||
|
||
}, | ||
|
||
// get the irradiance (radiance convolved with cosine lobe) in the direction of the normal | ||
// target is a Vector3 | ||
// https://graphics.stanford.edu/papers/envmap/envmap.pdf | ||
getIrradianceAt: function ( normal, target ) { | ||
|
||
// normal is assumed to be unit length | ||
|
||
var x = normal.x, y = normal.y, z = normal.z; | ||
|
||
var coeff = this.coefficients; | ||
|
||
// band 0 | ||
target = coeff[ 0 ] * 0.886227; // π * 0.282095 | ||
|
||
// band 1 | ||
target += coeff[ 1 ] * 2.0 * 0.511664 * y; // ( 2 * π / 3 ) * 0.488603 | ||
target += coeff[ 2 ] * 2.0 * 0.511664 * z; | ||
target += coeff[ 3 ] * 2.0 * 0.511664 * x; | ||
|
||
// band 2 | ||
target += coeff[ 4 ] * 2.0 * 0.429043 * x * y; // ( π / 4 ) * 1.092548 | ||
target += coeff[ 5 ] * 2.0 * 0.429043 * y * z; | ||
target += coeff[ 6 ] * ( 0.743125 * z * z - 0.247708 ); // ( π / 4 ) * 0.315392 * 3 | ||
target += coeff[ 7 ] * 2.0 * 0.429043 * x * z; | ||
target += coeff[ 8 ] * 0.429043 * ( x * x - y * y ); // ( π / 4 ) * 0.546274 | ||
|
||
return target; | ||
|
||
}, | ||
|
||
add: function ( sh ) { | ||
|
||
for ( var i = 0; i < 9; i ++ ) { | ||
|
||
this.coefficients[ i ].add( sh.coefficients[ i ] ); | ||
|
||
} | ||
|
||
return this; | ||
|
||
}, | ||
|
||
|
||
scale: function ( s ) { | ||
|
||
for ( var i = 0; i < 9; i ++ ) { | ||
|
||
this.coefficients[ i ].multiplyScalar( s ); | ||
|
||
} | ||
|
||
return this; | ||
|
||
}, | ||
|
||
lerp: function ( sh, alpha ) { | ||
|
||
for ( var i = 0; i < 9; i ++ ) { | ||
|
||
this.coefficients[ i ].lerp( sh.coefficients[ i ], alpha ); | ||
|
||
} | ||
|
||
return this; | ||
|
||
}, | ||
|
||
equals: function ( sh ) { | ||
|
||
for ( var i = 0; i < 9; i ++ ) { | ||
|
||
if ( ! this.coefficients[ i ].equals( sh.coefficients[ i ] ) ) { | ||
|
||
return false; | ||
|
||
} | ||
|
||
} | ||
|
||
return true; | ||
|
||
}, | ||
|
||
copy: function ( sh ) { | ||
|
||
return this.set( sh.coefficients ); | ||
|
||
}, | ||
|
||
clone: function () { | ||
|
||
return new this.constructor().copy( this ); | ||
|
||
} | ||
|
||
} ); | ||
|
||
Object.assign( SphericalHarmonics3, { | ||
|
||
// evaluate the basis functions | ||
// shBasis is an Array[ 9 ] | ||
getBasisAt: function ( normal, shBasis ) { | ||
|
||
// normal is assumed to be unit length | ||
|
||
var x = normal.x, y = normal.y, z = normal.z; | ||
|
||
// band 0 | ||
shBasis[ 0 ] = 0.282095; | ||
|
||
// band 1 | ||
shBasis[ 1 ] = 0.488603 * y; | ||
shBasis[ 2 ] = 0.488603 * z; | ||
shBasis[ 3 ] = 0.488603 * x; | ||
|
||
// band 2 | ||
shBasis[ 4 ] = 1.092548 * x * y; | ||
shBasis[ 5 ] = 1.092548 * y * z; | ||
shBasis[ 6 ] = 0.315392 * ( 3 * z * z - 1 ); | ||
shBasis[ 7 ] = 1.092548 * x * z; | ||
shBasis[ 8 ] = 0.546274 * ( x * x - y * y ); | ||
|
||
} | ||
|
||
} ); | ||
|
||
export { SphericalHarmonics3 }; |