solved Move mesh relative to camera angle

[Hersir]

Hi, I am trying to move mesh relative to ArcRotateCamera alpha value. Basically it should move the same direction as mouse is moving (up, down, left, right) , works fine with 0 angle but different angles need to flip x/z and change their directions. What the best way to calculate direction vector from angle and 0 angle direction?

Working example: http://www.babylonjs-playground.com/#W8MYRB#7 (angle 0)

Not working: http://www.babylonjs-playground.com/#W8MYRB#10 (angle 55)

 

I tried to rotate vector using:

const matrix = BABYLON.Matrix.RotationAxis(BABYLON.Axis.Y, camera.alpha);
const movement = BABYLON.Vector3.TransformCoordinates(new BABYLON.Vector3(x, 0, z), matrix);

 

[Hersir]

Ok found how to fix: 

const matrix = BABYLON.Matrix.RotationAxis(BABYLON.Axis.Y, Math.PI - camera.alpha);
const movement = BABYLON.Vector3.TransformCoordinates(new BABYLON.Vector3(x * -1, 0, z * -1), matrix);

Will need to study a bit matrices to understand why Math.PI - camera.alpha was needed
Working version: http://www.babylonjs-playground.com/#W8MYRB#11