Sign in to follow this  

Image Rotation

This topic is 4093 days old which is more than the 365 day threshold we allow for new replies. Please post a new topic.

If you intended to correct an error in the post then please contact us.

Recommended Posts

Hi, i trying to write image rotation code and wouldliketo be able to work out the width and height of the rotated image as the angle of rotation increase, but i can get hte right formula. here and image of what i mean thanks

Share this post


Link to post
Share on other sites
When you rotate by a small amount, the left-vertical side gets 'smaller' while the top-horizontal gets bigger (as projected to a vertical line). The height of the resulting canvas is the sum of these two.

The projected height of the verticals of any rectangle are
h' = h.cos(theta)
and similarly, the projected height of the horizontals are:
w' = w.sin(theta)

So the overall height of the image becomes
H = h.cos(theta) + w.sin(theta)
A similar calculation finds the canvas width to be
W = h.sin(theta) + w.cos(theta)

Since you are working with a square, these values become one and the same:
L = l(sin(theta) + cos(theta))
L = l.sqrt(2).sin(theta + pi/4)
where l = 8, in the diagram.

Regards
Admiral

Share this post


Link to post
Share on other sites

This topic is 4093 days old which is more than the 365 day threshold we allow for new replies. Please post a new topic.

If you intended to correct an error in the post then please contact us.

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now

Sign in to follow this