Mirroring and rotating are two easy ways to transform entire selections of sample points in the texture editor.
Mirroring "flips" a selection of sample points horizontally or vertically.
As the name indicates, the rotate commands rotates a selection of sample points by 90 degrees clockwise or counterclockwise. A second set of rotate commands does the same thing while maintaining the selection's aspect ratio (see Setting the Pivot for Scaling and Rotation).
To rotate a selection of sample points
In the texture editor or a 3D view, select the polygons that you want to rotate.
From the texture editor menu, choose Tools Rotate by 90 CW, or press R, to rotate the coordinates clockwise.
From the texture editor menu, choose Tools Rotate by 90 CCW, or press Shift+R, to rotate the coordinates counterclockwise.
From the texture editor menu, choose Tools Rotate by 90 CW (Maintain Aspect Ratio), or press Alt+R, to rotate the coordinates clockwise while maintaining their aspect ratio.
From the texture editor menu, choose Tools Rotate by 90 CCW (Maintain Aspect Ratio), or press Alt+ Shift+R, to rotate the coordinates counterclockwise while maintaining their aspect ratio.