Little snippet of handy code (in perl), how to adjust 2 dimentional latitude / longitude co-ordinates for plotting on a sphere.
rotAngle = 0; # Rotational offset
padX = 0; # Initial padding on Y axis
padY = 0; # Initial padding on X axis
posX = 0;
posY = 0;
posY = 0.5 * log( (1 + sin(lat)) / (1 - sin(lat)) ); # mercator latitude projection
if (rotAngle != 0) {
hyp = root((posX^2) + (posY^2));
posX = ((cos rotAngle) * hyp);
posY = ((sin rotAngle) * hyp);
}
posY += padY;
posX += padX;