Problem with rotating a polygon

        
int CPolygon2D::Rotate_Polygon2D(int theta)
{
	float xr,yr;
        int curr_vert;

        // test for negative rotation angle

	if (theta < 0)
		theta+=360;
	
	// loop and rotate each point

	for (curr_vert=0; curr_vert<num_verts; curr_vert++)
        {
		// perform rotation

		xr=(float)vlist[curr_vert].x*cos_look[theta] - 
		   (float)vlist[curr_vert].y*sin_look[theta];
		
		yr=(float)vlist[curr_vert].x*sin_look[theta] + 
		   (float)vlist[curr_vert].y*cos_look[theta];
		
		// store result back

		vlist[curr_vert].x = xr;
		vlist[curr_vert].y = yr;
		
         } 	
	// return success

	return(1);
	
}

Heres my CPolygon2D class (only the relevant stuff):


class CPolygon2D
{
public:
	
	int state;        // state of polygon

	int num_verts;    // number of vertices

	int x0,y0;        // position of center of polygon  

	int xv,yv;        // initial velocity

	DWORD color;      // could be index or PALETTENTRY

	VERTEX2DF *vlist; // pointer to vertex list

	
	
	int Rotate_Polygon2D(int theta);
	
	
};