Parallax scrolling: Difference between revisions

Revision as of 05:18, 8 May 2005

Revision as of 22:25, 9 May 2005

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'''Parallax scrolling''' is a special [[scrolling]] technique in [[computer graphics]]. It gives a 2D [[video game]] a greater sense of depth and immersion by creating the illusion of a third dimension.

There are three main methods of [[parallax]] scrolling used in titles for [[video game console]] systems. TheParallax firstscrolling gamewas tofirst featureused parallaxin scrollingthe was an[[1982]] [[arcade game called]] [[Moon Patrol]].

=== The layer way ===

Some display systems support multiple background layers that can be [[Scrolling|scrolled]] independently in horizontal and vertical directions and [[Compositing|composited]] on one another. On such a display system, a game can produce parallax by simply changing each layer's horizontal position by a different amount in the same direction. Layers that move more quickly are perceived to be closer to the virtual camera. However, placing too much in front of the ''playfield'', the layer containing the objects with which the player interacts, obscures the action of the game and may distract the player.

=== The raster way ===

In [[raster graphics]], the lines of pixels in an image are typically composited and refreshed in top-to-bottom order, and there is a slight delay, called [[horizontal blank]], between drawing one line and drawing the next line.

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If the display system supports rotation and scaling in addition to scrolling, an effect popularly known as [[Mode 7]], changing the rotation and scaling factors can draw a projection of a plane (''[[F-Zero]]'', ''[[Super Mario Kart]]'') or can warp the playfield to create an extra challenge factor (''[[Tetanus On Drugs]]'').

=== The sprite way ===

If there is much in the way of the [[sprite (computer graphics)|sprite]]s (individually controllable moving objects drawn by hardware on top of or behind the layers) available on the display system, the programmer may want to make a pseudo-layer out of sprites. ''[[Star Force]]'', an overhead-view vertically-scrolling shooter for NES, used this for its starfield, and ''[[Final Fight]]'' for Super NES used this technique for the layer immediately in front of the main playfield.