Skip to content

Quaternion - Support extrapolation in slerp methods #32541

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Merged
mrdoob merged 2 commits into from
Dec 13, 2025
Merged

Quaternion - Support extrapolation in slerp methods #32541

Show file tree
Hide file tree
Changes from all commits
Commits
Show all changes
2 commits
Select commit Hold shift + click to select a range
436115c
Support extrapolation in slerp methods
WestLangley Dec 13, 2025
c45e4f9
Update unit test
WestLangley Dec 13, 2025
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
32 changes: 3 additions & 29 deletions src/math/Quaternion.js
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -54,7 +54,7 @@ class Quaternion {
* @param {number} srcOffset0 - An offset into the first source array.
* @param {Array<number>} src1 - The source array of the second quaternion.
* @param {number} srcOffset1 - An offset into the second source array.
* @param {number} t - The interpolation factor in the range `[0,1]`.
* @param {number} t - The interpolation factor. A value in the range `[0,1]` will interpolate. A value outside the range `[0,1]` will extrapolate.
* @see {@link Quaternion#slerp}
*/
static slerpFlat( dst, dstOffset, src0, srcOffset0, src1, srcOffset1, t ) {
Expand All @@ -69,28 +69,6 @@ class Quaternion {
z1 = src1[ srcOffset1 + 2 ],
w1 = src1[ srcOffset1 + 3 ];

if ( t <= 0 ) {

dst[ dstOffset + 0 ] = x0;
dst[ dstOffset + 1 ] = y0;
dst[ dstOffset + 2 ] = z0;
dst[ dstOffset + 3 ] = w0;

return;

}

if ( t >= 1 ) {

dst[ dstOffset + 0 ] = x1;
dst[ dstOffset + 1 ] = y1;
dst[ dstOffset + 2 ] = z1;
dst[ dstOffset + 3 ] = w1;

return;

}

if ( w0 !== w1 || x0 !== x1 || y0 !== y1 || z0 !== z1 ) {

let dot = x0 * x1 + y0 * y1 + z0 * z1 + w0 * w1;
Expand Down Expand Up @@ -732,18 +710,14 @@ class Quaternion {
}

/**
* Performs a spherical linear interpolation between quaternions.
* Performs a spherical linear interpolation between this quaternion and the target quaternion.
*
* @param {Quaternion} qb - The target quaternion.
* @param {number} t - The interpolation factor in the closed interval `[0, 1]`.
* @param {number} t - The interpolation factor. A value in the range `[0,1]` will interpolate. A value outside the range `[0,1]` will extrapolate.
* @return {Quaternion} A reference to this quaternion.
*/
slerp( qb, t ) {

if ( t <= 0 ) return this;

if ( t >= 1 ) return this.copy( qb ); // copy calls _onChangeCallback()

let x = qb._x, y = qb._y, z = qb._z, w = qb._w;

let dot = this.dot( qb );
Expand Down
4 changes: 2 additions & 2 deletions test/unit/src/math/Quaternion.tests.js
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -628,8 +628,8 @@ export default QUnit.module( 'Maths', () => {

QUnit.test( 'slerp', ( assert ) => {

const a = new Quaternion( x, y, z, w );
const b = new Quaternion( - x, - y, - z, - w );
const a = new Quaternion( x, y, z, w ).normalize();
const b = new Quaternion( w, x, y, z ).normalize();
Copy link
Collaborator Author

@WestLangley WestLangley Dec 13, 2025

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

This test case was failing.

A quaternion and its negation represent the same rotation, so the equality test used here is invalid.

For now, I made an arbitrary change that passes the test.


const c = a.clone().slerp( b, 0 );
const d = a.clone().slerp( b, 1 );
Expand Down