If this is for a directX game construct 360 vertices one from each degree of rotation and then allow directX to render the necessary lines.
Example code (i just wrote this up here, so there may be errors0
Code:void render(int xLoc, int yLoc, int rad){ //create pLine here, dont feel like looking up params list for D3DXCreateLine() D3DXVECTOR2 vec[360]; for(int i = 0; i < 360; ++i){ vec[i].x=xLoc+(rad*cos((i)*(PI/180))); vec[i].y=yLoc+(rad*sin((i)*(PI/180))); } pLine->Begin(); pLine->Draw(vec,360,D3DCOLOR_XRGB(10,200,10)); pLine->End(); }