Editing Scanline rendering (section)

==Comparison with Z-buffer algorithm==

The main advantage of scanline rendering over [[Z-buffering]] is that the number of times visible pixels are processed is kept to the absolute minimum which is always one time if no transparency effects are used—a benefit for the case of high resolution or expensive shading computations.

In modern Z-buffer systems, similar benefits can be gained through rough front-to-back sorting (approaching the 'reverse painters algorithm'), early Z-reject (in conjunction with hierarchical Z), and less common deferred rendering techniques possible on programmable GPUs.

Scanline techniques working on the raster have the drawback that overload is not handled gracefully.

The technique is not considered to scale well as the number of primitives increases. This is because of the size of the intermediate datastructures required during rendering—which can exceed the size of a Z-buffer for a complex scene.

Consequently, in contemporary interactive graphics applications, the Z-buffer has become ubiquitous. The Z-buffer allows larger volumes of primitives to be traversed linearly, in parallel, in a manner friendly to modern hardware. Transformed coordinates, attribute gradients, etc., need never leave the graphics chip; only the visible pixels and depth values are stored.