I am using rapier physics with R3f, using pmndrs Ecctrl.

 // returns the current player position or a default position
  const calculatePosition = useCallback((pos, addMe) => {
    if (ecctrlRef.current) {
      try {
        const { x, y, z } = ecctrlRef.current.translation()
        if (addMe) {
          const [a, b, c] = addMe
          return [x + a, y + b, z + c]
        }
        return [x, y, z]
      } catch (err) {

      }
    }
    return pos
  }, [])
  const [cameraRotation, setCameraRotation] = useState([0,0,0])
  const calculateRotation = useCallback(([x, y, z]) => {
    const [cx, cy, cz] = cameraRotation
    return [x + cx, y + cy, z +cz]
  })
  const objectRefs = useRef([])
  const [objects, setObjects] = useState([])
  const calculateVelocity = ([rx, ry, rz], mag = 0) => {
    const destX = Math.sin(ry) * mag
    const destY = Math.sin(rx) * mag
    const destZ = Math.cos(ry) * mag
    return [destX, destY, destZ]
  }
  const createObject = () => {
    const rotation = calculateRotation([0, 0, 0])
    return {
      id: Math.random() + '',
      position: calculatePosition([0, 2, 1], [0, 0, 1]),
      velocity: calculateVelocity(rotation, 3),
      color: (0xffffff - Math.random() * 0x444444),
    }
  }
  const throwObject = () => {
    setObjects(obj => ([...obj, createObject()]))
  }

const GetCameraData = ({ setCameraRotation }) => {
  useFrame(({ camera }) => {
    const { x, y, z } = camera.rotation
    setCameraRotation([x, y, z])
  })
  return null
}
const RigidSphere = ({ velocity = [0, 1, 0], position = [0, 0, 0], color = 0xffffff }) => {
  const ref = useRef()
  const [thrown, setThrown] = useState(false)
  useFrame(() => {
    if (!thrown) {
      const [x, y, z] = velocity
      ref.current.addForce({ x, y, z }, true)
      setThrown(true)
    } else {
      ref.current.resetForces(true)
    }
  })
  return <RigidBody ref={ref} colliders="ball">
    <Sphere scale={0.1} position={position}>
      <meshLambertMaterial color={color} />
    </Sphere>
  </RigidBody>
}

rendering

 <Canvas
            shadows
            linear
            flat
            onPointerDown={(e) => {
              if (currentLevelData.type === ECCTRL) {
                if (e.pointerType === "mouse") {
                  try {
                    e.target.requestPointerLock();
                  } catch (err) {
                    console.warn('unable to get pointer lock', err)
                  }
                }
              }
            }}
            onPointerUp={(e) => {
              if (level === MINIGAME_THROW) {
                throwObject()
              }
            }}
          >
Suspense fallback={null}>
              <Physics timeStep="vary">
                {levelJsx}
                {objects.map((props) => <RigidSphere key={props.id} {...props} />)}
              </Physics>
            </Suspense>}
    

<GetCameraData setCameraRotation={setCameraRotation}/>
</Canvas>

Specifically I’m struggling with the math for calculateVelocity.

I’m passing in an Euler x, y, z rotation and a magnitude, at which to throw the Sphere. I want to calculate the velocity I need to give the rigidBody.addForce(velocity, wakeUp) but I’m not sure on the maths.

Thanks.