Sprite Scaling

Overview

As game hardware improved, sprite scaling became a popular technique, first for arcade games in the 1980s, and then for console and computer games in the 1990s. Scaling allowed for characters, items, or other sprites to smoothly grow or shrink on the fly, allowing the development of three-dimensional games using sprites. Sprite-scaling was an early form of 3D texture-mapping.

History

The first games to use sprite-scaling were arcade driving/racing games, by companies such as Sega and Namco; some of the earliest examples include Sega's Fonz (1976) and Turbo (1981), and Namco's Pole Position (1982). Some of the earliest action games to make use of extensive sprite-scaling were Sega's SubRoc-3D (1982) and Buck Rogers: Planet of Zoom (1982).

Super Scaler

See: Super Scaler

Sprite-scaling was later popularized by Sega's powerful Super Scaler arcade graphics boards, which were capable of scaling thousands of sprites every second; some of Sega's popular Super Scaler arcade games included Hang-On (1985), Space Harrier (1985) and Out Run (1986). With After Burner (1987), Sega introduced sprite rotation, adding greater three-dimensional depth. They continued producing hits such as Thunder Blade (1987), Galaxy Force (1988) and Last Survivor (1988).

Following the success of Sega's Super Scaler games, rival arcade developers such as Konami, Namco and Taito began producing their own sprite-scaling arcade games in the late 80s.

X68000 and Neo Geo

See: Sharp X68000 and Neo Geo

Among home gaming systems, the Sharp X68000 computer (launched 1987) was capable of smooth sprite-scaling, though it wasn't able to scale as many sprites as Sega's Super Scaler arcade systems.

SNK's Neo•Geo arcade-based console (launched 1990) was notorious for utilizing sprite scaling in its fighting games to simulate a camera "zooming" in and out of the actions depending on how close the combatants were to each other.

Mode 7

See: Mode 7

Another popular type of sprite-scaling was Mode 7, used to scale and rotate backgrounds for various games on the SNES console (launched 1990).

Billboarding

See: Billboarding

While long past its heyday, sprite-scaling is still used today in polygonal 3D games, in the form of billboarding. This technique was commonly used for rendering trees in early 3D games, although this has become less common in modern games. It is still frequently used when rendering smoke and fire.

Hardware Capabilities

This is a table listing the sprite scaling/zooming and rotation/mirroring capabilities of various classic gaming systems and/or graphics chips. Only systems and chips with hardware support for some form of hardware zooming/scaling or rotation/mirroring are listed here.

Integer zooming (including 1/2/4/8× vertical and 1/2/4/8× horizontal) indicates that sprites can only be zoomed in terms of integers (such as doubling or quadrupling), rather than smooth scaling. Voltage control indicates an analog method of smooth scaling through hardware voltage control. Anisotropic and affline indicate smooth scaling, i.e. what usually comes to mind when thinking of sprite scaling. Similarly for rotation effects, screen orientation means the screen can only be rotated in right-angles, while mirroring means it can only be flipped, whereas affline indicates smooth rotation.

For the other sprite capabilities of these systems and chips, see here. For a full detailed table of sprite capabilities, with references, see here.