There really isn't a way to do it manually. Well a very hacky way could be to have a square Sprite and a triangle Sprite. Then you take the for points and figure out how to make it out of rectangles and triangles with the requirement that the triangles can't be scaled up.
Another could be to have four scaled sprite with the destination out blend to erase parts of a colored Sprite.
But really those plugins add features that aren't doable with vanilla c2.