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比较2D和3D技术在当今游戏行业的重要性

发布时间:2013-10-03 08:42:15 Tags:,,,,

作者:Soren Johnson

游戏产业最早的一款电子游戏《Pong》,《行星游戏》和《太空入侵者》等必然都是2D游戏。一些早前游戏如《终极战区》的向量式坦克模拟器也尝试了基本的3D元素,但是在当时这些游戏却并未成为主流。1992年随着id Software的《德军总部3D》的问世,一切便开始发生改变,即人们开始将3D作为游戏开发的前缘。自那时起,几乎产业中的任何角落都开始了从2D到3D的过度。包括《马里奥》,《塞尔达传说》甚至是《吃豆人》也都尝试过3D技术。

既然这种转变基本上完成了,现在便是时候问问我们自己在这个过程中学到了什么。3D的优势是什么?这具有怎样的挑战?2D是否还是最佳选择?也许现在的游戏开发者至少可以根据实力选择最佳图像环境而不只是出于竞争压力才转向3D。

镜头的问题

3D游戏和镜头拥有一个很长且多灾多难的历史。尽管对于3D来说第一人称游戏是个已解决的问题,但是大多数其它类型的游戏仍然在适应这一新技术。在教授玩家使用镜头的同时教授游戏的核心体验是个非常困难的挑战。2D游戏所拥有的一个不同优势便是,根本不需要教授玩家如何使用镜头。实际上,3D将不再能够提供给玩家广泛的镜头控制。

God of War(from leviathyn)

God of War(from leviathyn)

《超级马里奥64》被认为是第一款成功的3D平台游戏,但是它要求玩家通过大量使用镜头控制去确保马里奥能够待在镜头里,并朝着正确的方向前进。在过去几年里平台游戏尝试了更加智能的镜头系统,并尝试着在任何时候通过动态化决定最佳视角。但是这种解决方法必然会在某种情况下遭遇失败,如当角色在角落后或暗礁下方受困时。为了解决这一棘手的问题,《波斯王子:时之砂》使用了2种交替的静态镜头视角,让玩家可以随时使用。《战神》进一步延伸了这一方法,并为游戏的每个场景执行了一个固定的镜头,让玩家能像电影摄影师那样面对关卡设计。《超级马里奥银河》拥有一个无需控制的动态镜头,它将通过自上而下视角让玩家始终都能看到周边区域。还有其它基于角色的游戏,如《魔兽世界》便避免让玩家在移动的时候转换镜头,如此能够确保玩家不会笔直朝镜头跑去。

策略游戏也经历了镜头系统的发展,同样倾向于避免玩家去控制镜头,或至少不让新手这么做。作为最初的3D RTS游戏之一,《星球大战:原力指挥官》拥有一个非常困难的自由镜头,玩家经常需要找到适当的角度去观看自己的军队。《魔兽争霸3》被当成是第一款正确使用3D的RTS游戏。设计师通过限制镜头的自由而做到这点——变焦范围非常小,界面角直接源自变焦,唯一的镜头旋转是附在一个模糊的热键上。首席设计师Rob Pardo描写了这些限制背后的过程:

对于3D,我们决定降低镜头的高度并尝试一些做法。而问题在于当镜头下放时,这便会变成一种虚假的第三人称体验。当你在地图上行走时将会迷失方向,如此你便很难在战斗中选择单位,因为你的镜头截锥是指着一个方向,所以你在战场上并未拥有较好的视野。因为我们仍然想要一款有趣的策略游戏,所以这便是一大挑战。最终我们将把镜头拖到更传统的等距视图中,那也是我们发展的起点。

而2D呢?

并非所有的2D游戏都是一样的。我们主要开发的是2种类型游戏:“经典的”2D,即基于直接自上而下(如象棋/西洋棋)或侧面(《索尼克》)视角,或等距2D,即尝试着在预制视角中通过等角投影的方式模仿3D视角。在完全跃向3D之前,许多游戏类型将从经典的2D到等距2D的转变作为中间步。举个例子来说,最初的《文明》拥有传统的自上而下网格视图,而《文明2》则拥有四分之三的等距视图。尽管这一新视角赋予了游戏世界更加生活化的外观,但这却是以牺牲玩家的游戏体验为代价换来的。换句话说,基于等距网格我们便更难判断距离,因为东西轴线所占据的像素是南北轴线的2倍。为了在《文明4》中解决这一问题,我们的3D视角回到了最初游戏中,即我们向前呈现游戏的网格,而不是基于倾斜角度。如果玩家能够越轻松地通过图像理解网格,他们便能够更清楚地做出决定。

值得注意的是《超级大战争:毁灭之日》(该系列游戏的最新版本)支持传统棋盘视角,让玩家以直角的视角面向硬核游戏玩法。这一系列游戏“笨拙的”单位图像便是源自游戏呈现的局限性。与此相反的是,受到《高级战争》系列游戏很大影响的游戏《帝国时代:王的时代》选择将同样的游戏机制整合到等距2D世界中。这一转变并不算完全取得成功。不只因为很难遵循网格的即时性,同时还因为单位延伸到层面边缘之外,如果当单位群组相互重叠时,选择单位和位置将变成一大问题。因此,基于贴图的游戏如果能够有效适应自上而下视角的话便有可能取得更大的成功。

图像并不是游戏玩法

3D图像与3D游戏玩法并不相同。举个例子来说吧,两款科幻RTS游戏《家园》和《太阳帝国的原罪》使用非常相似的3D引擎去创造大规模且具有特别影响力的外太空战斗。然而它们未共享核心游戏玩法,即《家园》作为一款“真正的”3D游戏意味着玩家可以沿着z轴自由移动舰船,而《原罪》拥有2D游戏玩法,所以玩家能够基于一个单一的平面游戏,这便意味着不能在高于平面或低于平面的范围飞行。实际上,游戏本来能够基于2D引擎而运行;3D是平滑缩放并唤起外太空“感”的第二选择。最终该团队关于使用2D游戏玩法的决定帮助《原罪》避免呈现出《家园》那般复杂的界面。

还有许多其它混合例子存在,即游戏使用3D图像去选择平面2D游戏玩法。例如《任天堂明星大作战》便是在所有重要动画和流畅背景环境中使用3D引擎并在单一垂直平台上战斗的一款游戏。Cliff Bleszinski将《战争机器》的游戏玩法描写为经典2D平台游戏《生化尖兵》的垂直版本。比起使用抓钩在不同平台上攀登,《战争机器》的玩家会沿着一个垂直平面从一个掩蔽点“跳”到另一个掩蔽点。

文明(from rockpapershotgun)

文明(from rockpapershotgun)

基本上,大多数游戏都可以被划分成三种相互联系的游戏机制类别,但是在图像上却是半独立的:

基于贴图的游戏(《俄罗斯方块》,《战神的挑战》,《文明》,《绿洲》,《网络开拓史》)

单一平面游戏(《星际争霸》,《Madden》,《几何战争》,《超级玛丽兄弟》)

现实世界游戏(《传送门》,《超级玛丽奥银河》,《Burnout》,《Boom Blox》)

每种类别都具有自己的规则。现实世界游戏要求3D图像。当然,“现实”这一词并不是基于字面意义。就像《传送门》中的枪支就不是“现实的”,但因为用户期待它的独特行为能够与自己所生活的世界的物理性和重力相协调,所以他们才喜欢玩这款游戏。确保玩家能够基于现实世界进行设想的最简单方法便是让他们沉浸于3D环境中,不管是外观,行为还是感觉都趋于现实化。对于游戏来说这些环境便等于“你看到的便是你所得到的”。

另一方面,基于贴图的游戏通常在自上而下的2D游戏中表现得最好,即不会明确将玩家与核心游戏机制隔离开来。对于单一平台游戏,选择实质上就是美学和技术的结合。游戏的平台是否能够顺畅地支持3D图像?3D提供的优势是否能让技术变得有价值(不管是源于共享动画还是动态效果或者整体灵活性)?

不管怎样我们都低估了2D这一传统技术的潜能。开发者不应该低估3D引擎和资产管道的技术开支。此外,精致的2D图像并未过时。Habbo Hotel(游戏邦注:青少年社交游戏和在线虚拟社区)的首席设计师Sulka Haro指出他们在8年前发行的传统2D游戏在今天看来还是很出色。如果他们那时候使用3D技术的话,Habbo引擎可能就会变成他们的第二个或第三个引擎。当2D引擎启动并开始运行时,美术人员可以逐渐完善游戏的外观。如果2D能够明确并传达基本游戏机制的话,一切将会变得更好。

本文为游戏邦/gamerboom.com编译,拒绝任何不保留版权的转载,如需转载请联系:游戏邦

GD Column 2: 2D vs 3D

by Soren Johnson

The industry’s first video games – Pong, Asteroids, Space Invaders – were all 2D by necessity. A few early games experimented with basic 3D, such as Battlezone‘s vector-based tank simulator, but these games were simply interesting footnotes, not the mainstream. Everything changed in 1992 with id Software’s Wolfenstein 3D, which popularized 3D as the leading edge of game development. Since then, almost no corner of the industry has been left untouched by the transition from 2D to 3D graphics. Almost every franchise, from Mario to Zelda to even Pac-Man himself, has tried out 3D technology.

Now that this transition is essentially complete, it may finally be a good time to ask ourselves what we have learned in the process. What are the advantages of 3D? What are its challenges? For what is 2D still best? Perhaps game developers can now at last choose the best graphics environment on a game-by-game basis instead of making the move to 3D just from competitive pressure.

Troubles with Cameras

3D games and cameras have a long, troubled history. While first-person games are essentially a solved problem for 3D, most other genres are still adapting to the new technology. Teaching the player how to use a camera while also teaching the game’s core experience can be a tough challenge. One distinct advantage 2D games have is that easiest camera to teach is one which doesn’t exist. In fact, 3D game have been trending away from giving the player extensive camera controls.

Super Mario 64 is credited with being the first successful 3D platformer, but it required the player to make extensive use of the camera controls to keep Mario visible and heading in the right direction. Platformers attempted more intelligent camera systems over the years, trying to dynamically determine the best perspective at any given time. Such solutions, however, are bound to fail at some point, such as when the character gets stuck behind a corner or under a ledge. To solve this sticky problem, Prince of Persia: The Sands of Time introduced two alternative static camera perspectives that the player could access at any time. God of War took this approach a step further and enforced a single fixed camera for each of the game’s scenes, approaching the level design almost like a film cinematographer. Super Mario Galaxy has a dynamic camera without any controls whatsoever although it adopts a nearly top-down view to enable the player to always see the surrounding area. Other avatar-based games, such as World of Warcraft, prevent the player from tweaking the camera while moving, ensuring that the player can never end up running directly into the camera.

Strategy games have also gone through a progression of camera systems, similarly trending towards taking camera controls away from the player, or at least hiding them from the novice. Star Wars: Force Commander, one of the first 3D RTS games, had an infamously difficult free camera, which made finding the right angle to view your troops a constant chore. Warcraft 3 may be considered the first RTS to get 3D right. The designers achieved this feat by greatly restricting the camera’s freedom – the zoom range was minuscule, the pitch angle came directly from zoom, and the only camera rotation was attached to an obscure hot-key. Lead Designer Rob Pardo describes the process behind these restrictions:

With 3D, we decided to bring the camera down quite a bit and try out some things. The problem was with the camera pulled all the way down, it became a pseudo-third-person experience. It was disorienting when you went around the map, and it was difficult to select units in battle because your camera frustum was pointed in one direction so you didn’t have a good view of the battlefield. It was a challenge because we still wanted a fun strategy game. Eventually we pulled the camera into a more traditional isometric view, and that’s when we really started making progress.

But Which 2D?

Not all 2D games are the same. Two major styles have developed: “classic” 2D, which is a straight top-down (chess/checkers) or side-on (Sonic games) view, or isometric 2D, which tries to fake 3D with an isometric projection at a pre-set angle. Before making the full jump to 3D, many genres made a move from classic 2D to isometric 2D as an intermediary step. For example, the original Civilization had a traditional top-down grid view while Civ 2 had a three-quarters isometric view. While this new perspective gave the game world a more life-like appearance, the change did come at a cost to the user’s game experience. Namely, distances are much more difficult to judge on an isometric grid as the east-west axis takes up twice as many pixels as the north-south axis. To solve this problem, for Civ 4, our 3D perspective actually hearkened back to the original game as we showed the game’s grid straight ahead and not at an angle. The easier the players perceive the grid through the graphics, the better they can “see” their possible decisions.

It is significant that Advance Wars: Days of Ruin (DS), the latest version in this long-running series, has maintained the traditional chess-board view, keeping the player focused squarely on the core gameplay. The “chunky” unit art familiar to the series is a great example of an artistic style which flows from the limitations of the game’s presentation. In contrast, a game heavily influenced by the Advance Wars series – Age of Empires: The Age of Kings (DS) – chose to move the same game mechanics into an isometric 2D world. The transition was not altogether successful. Not only was the immediacy of the grid harder to follow, but because units extended beyond the edges of their tiles, selecting units and locations became a significant problem when groups of units overlapped one another. Thus, tile-based games tend to be more successful when a top-down view is adopted.

Graphics are not Gameplay

3D graphics are not the same things as 3D gameplay. For example, two sci-fi RTS games – Homeworld and Sins of a Solar Empire – use very similar 3D engines to recreate the vast scale and special effects of deep space combat. However, they do not share core gameplay as Homeworld is a “true” 3D game, meaning that ships could be moved freely along the z-axis, while Sins actually has 2D gameplay as the game is played on a single, flat plane, meaning that ships cannot fly above or below each other. In fact, the game could have been implemented with a 2D engine; using 3D was a secondary choice to enable smooth zooming and to evoke the “feel” of outer space. The team’s decision to adopt 2D gameplay saved Sins from the interface complications of Homeworld, which required two or three separate clicks to give units a destination in all three dimensions.

Many other example of hybrids exist, where games use 3D graphics to render essentially flat 2D gameplay. Super Smash Bros. Brawl, for example, is fought on a single, vertical plane that uses the 3D engine for the all-important animations and fluid background environments. Cliff Bleszinski has described the gameplay of Gear of War as a horizontal version of the classic 2D platform Bionic Commando. Instead of using the grappling hook to ascend from platform to platform, Gears players “jump” from cover point to cover point along a horizontal plane.

Essentially, most games can be divided into three play mechanic categories which are related to but semi-independent from the graphics:

Tile-Based Games (Tetris, Puzzle Quest, Civilization, Oasis, NetHack)

Single-Plane Games (Starcraft, Madden, Geometry Wars, Super Mario Bros.)

Real-World Games (Portal, Super Mario Galaxy, Burnout, Boom Blox)

Good rules-of-thumb exist for each of these categories. Real-world games essentially require 3D graphics. Of course, the term “real” is not meant to be taken literally. The gun from Portal is not real, but the user enjoys playing with it because of the expectation that its unique behavior exists in harmony with the physics and gravity of our own world. The easiest way to guarantee that the player bring along assumptions from the real world is to immerse them in a 3D environment that looks, behaves, and feels real. These environments are the equivalent of what-you-see-is-what-you-get for games.

On the other hand, tile-based games usually work best as top-down 2D games, with little separating the player from the core game mechanics. For single-plane games, the choice comes down to largely one of aesthetics and technology. Can the game’s platform support 3D graphics smoothly? Does 3D provide an advantage, from either shared animations or dynamic effects or general flexibility, that makes the technology worthwhile?

All in all, 2D is an underrated style that is often unfairly ignored as an old technology. Developers should not underestimate the advantages of avoiding the technical overhead of maintaining a bulky 3D engine and asset pipeline. Furthermore, well-made 2D graphics never really go obsolete. Sulka Haro, lead designer of Habbo Hotel, likes to point out that their retro 2D style looks just as good today as when the game launched eight years ago. If they had used 3D, Habbo would probably be on its second or third engine by now. Once a 2D engine is up and running, the artists can focus on simply improving the game’s look piece by piece. If 2D helps clarify and communicate the underlying game mechanic, then all the better.(source:designer-notes


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