伪三维

title: 近大远小.
content: 在某些游戏里,部分物体的大小会随着与玩家的远近不同而改变。世嘉于1986年发布的游戏"Out Run" 就是一个典型例子。  在"Out Run" 中,玩家需驾驶一辆法拉利深入游戏场景。街道两侧的棕榈树虽使用同一个位图,但被缩放到不同的大小以营造远近感。大量消耗内存的看板被"Out Run" 用于渲染即使在最高能见度模式下也看不到边际的水波和玉米地。  Sega's arcade shooter "Space Tactics", released in 1980, allowed players to take aim using crosshairs and shoot lasers into the screen at enemies coming towards them, creating an early 3D effect. It was followed by other arcade shooters with a first-person perspective during the early 1980s, including Taito's 1981 release "Space Seeker", and Sega's "Star Trek" in 1982. Sega's "SubRoc-3D" in 1982 also featured a first-person perspective and introduced the use of stereoscopic 3-D through a special eyepiece. Sega's "Astron Belt" in 1983 was the first laserdisc video game, using full-motion video to display the graphics from a first-person perspective. Third-person rail shooters were also released in arcades at the time, including Sega's "Tac/Scan" in 1982, Nippon's "Ambush" in 1983, Nichibutsu's "Tube Panic" in 1983, and Sega's 1982 release "", notable for its fast pseudo-3D scaling and detailed sprites.  In 1981, Sega's "Turbo" was the first racing game to feature a third-person perspective, rear view format. It was also the first racing game to use sprite scaling with full-colour graphics. "Pole Position" by Namco is one of the first racing games to use the trailing camera effect that is now so familiar. In this particular example, the effect was produced by linescroll—the practice of scrolling each line independently in order to warp an image. In this case, the warping would simulate curves and steering. To make the road appear to move towards the player, per-line color changes were used, though many console versions opted for palette animation instead.  "Zaxxon", a shooter introduced by Sega in 1982, was the first game to use isometric axonometric projection, from which its name is derived. Though Zaxxon's playing field is semantically 3D, the game has many constraints which classify it as 2.5D: a fixed point of view, scene composition from sprites, and movements such as bullet shots restricted to straight lines along the axes. It was also one of the first video games to display shadows. The following year, Sega released the first pseudo-3D isometric platformer, "Congo Bongo". Another early pseudo-3D platform game released that year was Konami's "Antarctic Adventure", where the player controls a penguin in a forward-scrolling third-person perspective while having to jump over pits and obstacles. It was one of the earliest pseudo-3D games available on a computer, released for the MSX in 1983. That same year, Irem's "Moon Patrol" was a side-scrolling run & gun platform-shooter that introduced the use of layered parallax scrolling to give a pseudo-3D effect. In 1985, "Space Harrier" introduced Sega's "Super Scaler" technology that allowed pseudo-3D sprite-scaling at high frame rates, with the ability to scale 32,000 sprites and fill a moving landscape with them.  The first original home console game to use pseudo-3D, and also the first to use multiple camera angles mirrored on television sports broadcasts, was "Intellivision World Series Baseball" (1983) by Don Daglow and Eddie Dombrower, published by Mattel. Its television sports style of display was later adopted by 3D sports games and is now used by virtually all major team sports titles. In 1984, Sega ported several pseudo-3D arcade games to the Sega SG-1000 console, including a smooth conversion of the third-person pseudo-3D rail shooter "Buck Rogers: Planet of Zoom".  With the advent of consoles and computer systems that were able to handle several thousands of polygons (the most basic element of "3D computer graphics") per second and the usage of 3D specialized graphics processing unit, pseudo 3D became obsolete. But even today, there are computer systems in production, such as cellphones, which are often not powerful enough to display "true" 3D graphics, and therefore use pseudo-3D for that purpose. Interestingly, many games from the 1980s' "pseudo-3D arcade era" and "16-bit console era" are ported to these systems, giving the manufactures the possibility to earn revenues from games that are now nearly twenty years old.

Summary: 伪三维(又称为2.5D、假3D),是一种用于在二维画面中所应用的技术,使得图像或场景有着三维的视觉效果。对于电子游戏来说,多边形技术未成熟或是游戏主机(电脑、电子游戏机)机能不足以支持的时代,产生了许多过渡产物。此类游戏虽然有着看似立体的外观,可是却并非真正意义上的三维游戏,因此一般都统称为伪三维游戏。在部分三维图形游戏中,仅使用平面坐标或使用固定相机位置的游戏同样被称作伪三维游戏。作为对比,没有以上限制的三维图形技术游戏就被称为真三维游戏。

2.5D: The two-and-a-half-dimensional (2.5D, alternatively three-quarter and pseudo-3D) perspective is either 2D graphical projections and similar techniques used to cause images or scenes to simulate the appearance of being three-dimensional (3D) when in fact they are not, or gameplay in an otherwise three-dimensional video game that is restricted to a two-dimensional plane with a limited access to the third dimension. By contrast, games using 3D computer graphics without such restrictions are said to use "true 3D".