Program to convert image and rotate

I've been trying to make this program in c++ with opencv that converts the image to greyscale and rotates the image afterwards, but the output I get is all kinds of messed up.

I haven't been able to find what the hell I have done wrong so if any of you could help me it'd be great

http://pastebin.com/FSJKyaeU

>>1
Just move each pixel to a x*(cos angle), y*(sin angle), then fill result pixels with closest matching rotated-neighbors. Using a simple N-linear interpolation will greatly increase rotation quality.