How To Multiply A Quaternion With A Vector3

Questions
5

Yo @Raggar … Thank a bunch… You too @JohnK…

I think i am going to try and use this in my Utilities

        /** Multiply the quaternion by a vector */
        public static MultiplyQuaternionByVector(quaternion:BABYLON.Quaternion, vector:BABYLON.Vector3): BABYLON.Vector3 {
            const result:BABYLON.Vector3 = new BABYLON.Vector3(0,0,0);
            BABYLON.Utilities.MultiplyQuaternionByVectorToRef(quaternion, vector, result);
            return result;
        }
        /** Multiply the quaternion by a vector to result */
        public static MultiplyQuaternionByVectorToRef(quaternion:BABYLON.Quaternion, vector:BABYLON.Vector3, result:BABYLON.Vector3) : void {
            // Vector
            const x:number = vector.x;
            const y:number = vector.y;
            const z:number = vector.z;
            // Quaternion
            const qx:number = quaternion.x;
            const qy:number = quaternion.y;
            const qz:number = quaternion.z;
            const qw:number = quaternion.w;
            // Quaternion * Vector
            const ix:number =  qw * x + qy * z - qz * y;
            const iy:number =  qw * y + qz * x - qx * z;
            const iz:number =  qw * z + qx * y - qy * x;
            const iw:number = -qx * x - qy * y - qz * z;
            // Final Quaternion * Vector = Result
            result.x = ix * qw + iw * -qx + iy * -qz - iz * -qy;
            result.y = iy * qw + iw * -qy + iz * -qx - ix * -qz;
            result.z = iz * qw + iw * -qz + ix * -qy - iy * -qx;
        }

We shall see how that works… Ill let you know :slight_smile:

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