void Bullet::UpdatePosition()
{
    D3DXVECTOR3 rotationVector(0.0f, 1.0f, 0.0f);

    // rotation
    D3DXMATRIX rotateX;
    D3DXMATRIX rotateY;
    D3DXMATRIX rotateZ;
    D3DXMatrixRotationX(&rotateX, myModel->rotation.x);
    D3DXMatrixRotationY(&rotateY, myModel->rotation.y);
    D3DXMatrixRotationZ(&rotateZ, myModel->rotation.z);
    D3DXMATRIX rotationMatrix = rotateX*rotateY*rotateZ;
    D3DXVECTOR4 outputVec;

    D3DXVec3Transform(&outputVec, &rotationVector, &rotationMatrix);
    rotationVector.x = outputVec.x;
    rotationVector.y = outputVec.y;
    rotationVector.z = outputVec.z;

    myModel->position += (speed/200.0f*rotationVector*System::time);
    currentDistance = sqrt(pow(myModel->position.x - originPos.x, 2) + pow(myModel->position.y - originPos.y, 2));
}