Rotate Texture in function of player position

Question

I\'m making a 2d game that consists in a plane fighting against spaceships trough missiles, i want the spaceships to rotate in function of the player position, so that they are

Answer 1

I think this should work. Set..

v = centerPosOfShip - centerPosOfUFO

Normalize...

v /= sqrt( v.x * v.x + v.y * v.y )

So now we can say v = [ cos(theta) sin(theta) ]; the rotation matrix is...

[ cos(theta)  -sin(theta) ]
[ sin(theta)   cos(theta) ]

So we can write in terms of v-components...

[ v.x  -v.y    centerPosOfUFO.x ][x]
[ v.y   v.x    centerPosOfUFO.y ][y]
[ 0     0      1                ][1]

where [x y] is any point on the UFO relative to its center.

Hope that makes sense