vertecs/src/math/MathUtils.ts

A typescript entity-component-system framework

import { QuatLike, vec3, Vec3Like } from "ts-gl-matrix";

export default class MathUtils {
    public static getEulerToDegrees(radians: number): number {
        return radians * (180 / Math.PI);
    }

    /**
     * Convert a quaternion to euler angles.
     * Missing function from gl-matrix
     * @param quat
     * @param out
     */
    public static getEulerFromQuat(out: Vec3Like, quat: QuatLike): Vec3Like {
        const sinRCosP = 2 * (quat[3] * quat[0] + quat[1] * quat[2]);
        const cosRCosP = 1 - 2 * (quat[0] * quat[0] + quat[1] * quat[1]);
        const roll = Math.atan2(sinRCosP, cosRCosP);

        const sinP = 2 * (quat[3] * quat[1] - quat[2] * quat[0]);
        let pitch;
        if (Math.abs(sinP) >= 1) pitch = (Math.sign(sinP) * Math.PI) / 2;
        // use 90 degrees if out of range
        else pitch = Math.asin(sinP);

        const sinYCosP = 2 * (quat[3] * quat[2] + quat[0] * quat[1]);
        const cosYCosP = 1 - 2 * (quat[1] * quat[1] + quat[2] * quat[2]);
        const yaw = Math.atan2(sinYCosP, cosYCosP);

        vec3.set(
            out,
            MathUtils.getEulerToDegrees(roll),
            MathUtils.getEulerToDegrees(pitch),
            MathUtils.getEulerToDegrees(yaw)
        );

        return out;
    }
}