I have a rotated shape (by α) in a graphic scene. My task is to move its starting point(blue dot) to the red position.
Now, because the shape is rotated, it is not just simply adding (400;150) to its starting point. When I move the shape 'up' by 150 and 'right' by 400, it will move on the its own X and Y axis.
How could I move this shape to the position of red P?
Sorry for my very poor explanation.
To perform a translation with respect to the global coordinate axes (instead of the rotated local coordinate axes), premultiply the rotation matrix* you used to rotate the shape by a homogeneous transformation matrix that performs only the desired translation (and no rotation).
On the other hand, postmultiplication of your initial rotation matrix* by the pure translation homogeneous transformation matrix mentioned above would perform translation with respect to the local (rotated) coordinate axes.
*expressed as a homogeneous transformation matrix