I am the superclass for all rasterizers in the Balloon 3D engine. Rasterizers perform the final pixel generation of the primitives and are the most time-critical part of the engine. Rasterizers keep a viewport, defining the destination rectangle and a dirtyRect, defining the actual affected 2D region of the rasterization process.

Instance variables:
viewport <B3DViewport> the destination rectangle
dirtyRect <Rectangle> the affected region of all rasterization operations performed

	initialize
	finish flush initialize reset target:

	processing
	clearDepthBuffer clearViewport: processVertexBuffer:

	testing
	needsClip

	accessing	top
	clipRect Return the current clipping rectangle
	clipRect: Install a clipping rectangle if necessary
	dirtyRect If the dirtyRect is not known (e.g., not implemented by a particular rasterizer) return the full viewport
	dirtyRect:
	popTexture
	pushTexture
	texture
	texture:
	viewport
	viewport:
	viewportOffset Return the viewport offset
	viewportOffset: Set the viewport offset

	initialize	top
	finish Force everything on the output device
	flush Flush pending operations.
	initialize
	reset
	target: Set the target for rendering operations

	processing	top
	clearDepthBuffer If the rasterizer uses a depth buffer, clear it.
	clearViewport: Clear the current viewport using the given color
	processVertexBuffer: Process the given vertex buffer in this part of the engine.

	testing	top
	needsClip Return true if we need to clip polygons before rasterization. Generally, this should not be the case.