public WorldPosition PositionAt(float elapsed)
        {
            float periodFactor = 0;
            float amplitudeFactor = 0;
            float theta = 0;
            float t = 0;
            float x = 0;
            float y = 0;
            float sin = 0;
            float cos = 0;
            float halfway = 0;
            float deflection = 0;

            WorldPosition p = new WorldPosition(StartPos.X, StartPos.Y);

            float dist = elapsed * ((float)Desc.Speed / 10000.0f);
            float phase = BulletId % 2 == 0 ? 0 : (float)Math.PI;
            if (Desc.Wavy)
            {
                periodFactor = 6 * (float)Math.PI;
                amplitudeFactor = (float)Math.PI / 64.0f;
                theta = Angle + amplitudeFactor * (float)Math.Sin(phase + periodFactor * (float)elapsed / 1000.0f);
                p.X = p.X + dist * (float)Math.Cos(theta);
                p.Y = p.Y + dist * (float)Math.Sin(theta);
            }
            else if (Desc.Parametric)
            {
                t = (float)elapsed / LifetimeMS * 2 * (float)Math.PI;
                x = (float)Math.Sin(t) * (BulletId % 2 == 1 ? 1 : -1);
                y = (float)Math.Sin(2 * t) * (BulletId % 4 < 2 ? 1 : -1);
                sin = (float)Math.Sin(Angle);
                cos = (float)Math.Cos(Angle);
                p.X = p.X + (((x * cos) - (y * sin)) * Desc.Magnitude);
                p.Y = p.Y + (((x * sin) + (y * cos)) * Desc.Magnitude);
            }
            else
            {
                if (Desc.Boomerang)
                {
                    halfway = LifetimeMS * (Desc.Speed / 10000) / 2;
                    if (dist > halfway)
                    {
                        dist = halfway - (dist - halfway);
                    }
                }
                p.X = p.X + dist * (float)Math.Cos(Angle);
                p.Y = p.Y + dist * (float)Math.Sin(Angle);
                if (Desc.Amplitude != 0)
                {
                    deflection = Desc.Amplitude * (float)Math.Sin(phase + (float)elapsed / LifetimeMS * Desc.Frequency * 2 * (float)Math.PI);
                    p.X = p.X + deflection * (float)Math.Cos(Angle + (float)Math.PI / 2);
                    p.Y = p.Y + deflection * (float)Math.Sin(Angle + (float)Math.PI / 2);
                }
            }

            return p;
        }