@fimbul-works/vec/dist/esm/3d/rotate-y-3d.js

A comprehensive TypeScript vector math library providing 2D, 3D, and 4D vector operations with a focus on performance and type safety.

/**
 * Rotates a 3D vector around the y-axis.
 * @param {ArrayVector3D} xyz - Vector as `[x, y, z]`
 * @param {number} phi - Angle of rotation in radians
 * @param {ArrayVector3D} axis - Rotation axis point (default: `[0, 0, 0]`)
 * @returns {ArrayVector3D} The rotated vector
 */
export const rotateY3D = (xyz, phi, axis = [0, 0, 0]) => {
    const cosPhi = Math.cos(phi);
    const sinPhi = Math.sin(phi);
    if (axis[0] === 0 && axis[1] === 0 && axis[2] === 0) {
        return [xyz[0] * cosPhi + xyz[2] * sinPhi, xyz[1], -xyz[0] * sinPhi + xyz[2] * cosPhi];
    }
    // Translate point to origin (relative to axis)
    const translatedX = xyz[0] - axis[0];
    const translatedZ = xyz[2] - axis[2];
    // Rotate around origin
    const rotatedX = translatedX * cosPhi + translatedZ * sinPhi;
    const rotatedZ = -translatedX * sinPhi + translatedZ * cosPhi;
    // Translate back
    return [rotatedX + axis[0], xyz[1], rotatedZ + axis[2]];
};