ARCed.XnaExtensions.FillTriangle C# (CSharp) Method

        public static void FillTriangle(this SpriteBatch batch, Vector2 p1, Vector2 p2,
            Vector2 p3, Color color)
        {
            Vector2 tp;
            if (p2.Y > p1.Y) { tp = p1; p1 = p2; p2 = tp; }
            if (p3.Y > p1.Y) { tp = p1; p1 = p3; p3 = tp; }
            if (p3.Y > p2.Y) { tp = p2; p2 = p3; p3 = tp; }
            var steps13 = (int)(p1.Y - p3.Y);
            var steps12 = (int)(p1.Y - p2.Y);
            var steps23 = (int)(p2.Y - p3.Y);
            float sx13 = (p1.X - p3.X) / steps13;
            float sx12 = (p1.X - p2.X) / steps12;
            float sx23 = (p2.X - p3.X) / steps23;
            float x13 = p1.X;
            float x12 = p1.X;
            float dx = 1;
            for (int i = 0; i < steps12; i++)
            {
                x13 -= sx13;
                x12 -= sx12;
                dx = x13 - x12;
                if (dx > 0)
                    batch.FillRectangle((int)x12, (int)p1.Y - i, (int)Math.Abs(dx), 1, color);
                else
                    batch.FillRectangle((int)x13, (int)p1.Y - i, (int)Math.Abs(dx), 1, color);
            }
            float x23 = p2.X;
            for (int i = 0; i < steps23; i++)
            {
                x13 -= sx13;
                x23 -= sx23;
                dx = x13 - x23;
                if (dx > 0)
                    batch.FillRectangle((int)x23, (int)p2.Y - i, (int)Math.Abs(dx), 1, color);
                else
                    batch.FillRectangle((int)x13, (int)p2.Y - i, (int)Math.Abs(dx), 1, color);
            }
        }