I am sure that my title is miss leading to my actual question, but I am unsure of what i should call what I am looking for.
      First time poster to this forum, but long time processing user. I am quite familiar with the library but I am looking for what seems to be to be a trivial tool, I am sure that it does not exist in the core library but if there is a common practice to achieve the result i would like to know this. I would like to be able to declare some region, rectangular, and draw only to the pixels within. To illustrate what i mean: I may have declared to draw only in the region of (25,25) to (100,100). then latter called ellipse(25,75,25,25). I would expect there to be a half circle drawn halfway down on the left side.
      a quick google of this gave me an unsuitable mechanism, to draw normally then surrounding the desired area with rectangles or some other shape.