rotate an image based on a cordinate

Question

i need to rotate an image based on cordinate which moves 0 to 360 degree. i need to rotate the image to 90 degree, 180, 270 and 360 degree based on the location of coordinate.

which equation i can use?

Answer 1

When an image is rotated counterclockwise, the former positive x-axis becomes the new positive yaxis, and the former positive y axis becomes the new negative x axis.

 

This can be summarized as (x,y) ⇒ (-y,x).

 

You can apply this transformation two times in a row, for a ccw 180^o transformation.

 

Do it yet a third time for the ccw 270^o transformation.

 

Rotating 360^o accomplishes nothing--you're exactly back where you began as if no rotation had occurred.