 |
| Part of a series on |
| Video game graphics |
|---|
Isometric video game graphics are graphics employed invideo games andpixel art that use aparallel projection, but which angle theviewpoint to reveal facets of the environment that would otherwise not be visible from atop-down perspective orside view, thereby producing athree-dimensional (3D) effect. Despite the name, isometric computer graphics are not necessarily trulyisometric—i.e., thex,y, andz axes are not necessarily oriented 120° to each other. Instead, a variety of angles are used, withdimetric projection and a 2:1 pixel ratio being the most common. The terms "3/4 perspective", "3/4 view", "2.5D", and "pseudo 3D" are also sometimes used, although these terms can bear slightly different meanings in other contexts.
Once common, isometric projection became less so with the advent of more powerful3D graphics systems, and as video games began to focus more on action and individual characters.[1] However, video games using isometric projection—especiallycomputer role-playing games—have seen a resurgence in recent years within theindie gaming scene.[1][2]
A well-executed isometric system should never have the player thinking about the camera. You should be able to quickly and intuitively move the view to what you need to look at and never consider the camera mechanics. Trying to run a full-3D camera while playing out a real-time tactical battle is certain to cause ahelmet fire in new players as they are quickly overwhelmed by the mechanics.
Invideo game development andpixel art, the technique has become popular because of the ease with which2Dsprite- andtile-based graphics can be made to represent3D gaming environments. Becauseparallel projected objects do not change in size as they move about an area, there is no need for the computer to scalesprites or do the complex calculations necessary to simulatevisual perspective. This allowed8-bit and16-bit game systems (and, more recently,handheld andmobile systems) to portray large game areas quickly and easily. And, while thedepth confusion problems of parallel projection can sometimes be a problem, good game and level design can alleviate this.
Though not limited strictly to isometric video game graphics,pre-rendered 2D graphics can possess a higher fidelity and use more advanced graphical techniques than may be possible on commonly available computer hardware, even with3D hardware acceleration.[4] Similarly to modernCGI used inmotion pictures, graphics can be rendered one time on a powerfulsuper computer orrender farm, and then displayed many times on less powerful consumer hardware, such as ontelevision sets,tablet computers andsmartphones. This means that static pre-rendered isometric graphics often look better compared to their contemporary real-time-rendered counterparts, and may age better over time compared to their peers.[2] However, this advantage may be less pronounced today than it was in the past, as developments in graphical technology equalize or producediminishing returns, and current levels of graphical fidelity become "good enough" for many people.[citation needed]
There are also gameplay advantages to using an isometric or near-isometric perspective in video games. For instance, compared to a purelytop-down game, they add a third dimension, opening up new avenues for aiming andplatforming.[1] Compared to afirst- orthird-person video game, they allow a player to more easily field and control a large number of units, such as a fullparty of characters in acomputer role-playing game, or an army of minions in areal-time strategy game.[1] Further, they may alleviate situations where a player may become distracted from a game's coremechanics by having to constantly manage an unwieldy 3D camera.[1] I.e., the player can focus on playing the game itself, and not on manipulating the game's camera.[1]
In the present day, rather than being purely a source of nostalgia, the revival of isometric projection is the result tangible design benefits.[1]
Some disadvantages of pre-rendered isometric graphics are that, asdisplay resolutions anddisplay aspect ratios continue to evolve, static 2D images need to be re-rendered each time in order to keep pace, or potentially suffer from the effects ofpixelation and requireanti-aliasing. Re-rendering a game's graphics is not always possible, however; as was the case in 2012, whenBeamdogremade BioWare'sBaldur's Gate (1998). Beamdog were lacking the original developers' creative art assets (the original data was lost in a flood[5]) and opted for simple2D graphics scaling with "smoothing", without re-rendering the game's sprites. The results were a certain "fuzziness", or lack of "crispness", compared to the original game's graphics.[citation needed] This does not affect real-time rendered polygonal isometric video games, however, as changing their display resolutions or aspect ratios is trivial, in comparison.
 | This sectiondoes notcite anysources. Please helpimprove this section byadding citations to reliable sources. Unsourced material may be challenged andremoved.(March 2025) (Learn how and when to remove this message) |
The projection commonly used in video games deviates slightly from "true" isometric due to the limitations ofraster graphics. Lines in thex andy directions would not follow a neat pixel pattern if drawn in the required 30° to the horizontal. While modern computers can eliminate this problem usinganti-aliasing, earlier computer graphics did not support enough colors or possess enough CPU power to accomplish this. Instead, a 2:1 pixel pattern ratio would be used to draw thex andy axis lines, resulting in these axes following a ≈26.565° (arctan(1/2)) angle to the horizontal. (Game systems that do not usesquare pixels could, however, yield different angles, including "true" isometric.) Therefore, this form of projection is more accurately described as a variation ofdimetric projection, since only two of the three angles between the axes are equal to each other, i.e.,(≈116.565°, ≈116.565°, ≈126.870°).
Somethree-dimensional games were released as early as the 1970s, but the first video games to use the distinct visual style of isometric projection in the meaning described above werearcade games in the early 1980s.
The use of isometric graphics in video games began withData East's arcade gameTreasure Island,[6] released in Japan in September 1981,[7] but it was not released internationally until June 1982.[8] The first isometric game to be released internationally wasSega'sZaxxon, which was significantly more popular and influential;[9][10] it was released in Japan in December 1981[11] and internationally in April 1982.[8]Zaxxon is anisometric shooter where the player flies a space plane throughscrolling levels. It is also one of the first video games to display shadows.[9]
Another early isometric game isQ*bert.[12]Warren Davis and Jeff Lee began programming the concept around April 1982. The game's production began in the summer and then released in October or November 1982.[13]Q*bert shows a static pyramid in an isometric perspective, with the player controlling a character which can jump around on the pyramid.[9]
In February 1983,[8] theisometric platform game arcade gameCongo Bongo was released, running on the same hardware asZaxxon.[14] It allows the player character to traverse non-scrolling isometric levels, including three-dimensional climbing and falling. The same is possible in the arcade titleMarble Madness, released in 1984.
In 1983, isometric games were no longer exclusive to the arcade market and also entered home computers, with the release ofBlue Max for theAtari 8-bit computers andAnt Attack for theZX Spectrum. InAnt Attack, the player can move forward in any direction of the scrolling game, offering complete free movement rather than fixed to one axis as withZaxxon. The views can also be changed around a90 degrees axis.[15] The ZX Spectrum magazine,Crash, consequently awarded it 100% in the graphics category for this new technique, known as "Soft Solid 3-D".[16]
A year later, the ZX Spectrum gameKnight Lore was released. It was generally regarded as a revolutionary title[17] that defined the subsequent genre of isometric adventure games.[18] FollowingKnight Lore, many isometric titles were seen on home computers – to an extent that it once was regarded as being the second most cloned piece of software afterWordStar, according to researcher Jan Krikke.[19] Other examples out of those wereHighway Encounter (1985),Batman (1986),Head Over Heels (1987)[20] andLa Abadía del Crimen (1987).
Isometric perspective was not limited to action and adventure games. For example, the 1989 strategy gamePopulous uses isometric perspective.
Throughout the 1990s, a number of successful computer games used a fixed isometric perspective, such asA-Train III (1990),Syndicate (1993),SimCity 2000 (1994),Civilization II (1996),X-COM (1994), andDiablo (1996). But with the advent of3D acceleration on personal computers and gaming consoles, games previously using a 2D perspective generally started switching to true 3D (andperspective projection) instead. This can be seen in the successors to the above games: for instanceSimCity (2013),Civilization VI (2016),XCOM: Enemy Unknown (2012) andDiablo III (2012) all use 3D polygonal graphics; and whileDiablo II (2000) used fixed-perspective 2D perspective like its predecessor, it optionally allowed for perspective scaling of the sprites in the distance to lend it a "pseudo-3D" appearance.[22]
Also during the 1990s, isometric graphics began being used for Japaneserole-playing video games (JRPGs) onconsole systems, particularlytactical role-playing games, many of which still use isometric graphics today. Examples includeFront Mission (1995),Tactics Ogre (1995) andFinal Fantasy Tactics (1997)—the latter of which used3D graphics to create an environment where the player could freely rotate the camera. Other titles such asVandal Hearts (1996) andBreath of Fire III (1997) carefully emulated an isometric or parallel view, but actually used perspective projection.
Isometric, or similar, perspectives become popular inrole-playing video games, such asFallout andBaldur's Gate. In some cases, these role-playing games became defined by their isometric perspective, which allows larger scale battles.[1]
Isometric projection has seen continued relevance in the new millennium with the release of several newly-crowdfunded role-playing games onKickstarter.[1] These include theShadowrun Returns series (2013–2015) byHarebrained Schemes; thePillars of Eternity series (2015–2018) andTyranny (2016) byObsidian Entertainment; andTorment: Tides of Numenera (2017) byinXile Entertainment.[citation needed] Both Obsidian Entertainment and inXile Entertainment have employed, or were founded by, former members of Black Isle Studios and Interplay Entertainment. Obsidian Entertainment in particular wanted to "bring back the look and feel of theInfinity Engine games likeBaldur's Gate,Icewind Dale, andPlanescape: Torment".[1] Lastly, several pseudo-isometric 3D RPGs, such asDivinity: Original Sin (2014),Wasteland 2 (2014) andDead State (2014), have been crowdfunded using Kickstarter. These titles differ from the above games, however, in that they useperspective projection instead ofparallel projection.[citation needed]
The term "isometric perspective" is frequently misapplied to any game with an—usually fixed—angled, overhead view that appears at first to be "isometric". These include the aforementioneddimetrically projected video games; games that usetrimetric projection, such asFallout (1997)[23] andSimCity 4 (2003);[24] games that useoblique projection, such asUltima Online (1997)[25] andDivine Divinity (2002);[26] and games that use a combination ofperspective projection and abird's eye view, such asSilent Storm (2003),[27]Torchlight (2009)[28] andDivinity: Original Sin (2014).[29]
Also, not all "isometric" video games rely solely on pre-rendered 2D sprites. There are, for instance, titles which use polygonal 3D graphics completely, but render their graphics using parallel projection instead of perspective projection, such asSyndicate Wars (1996),Dungeon Keeper (1997) andDepths of Peril (2007); games which use a combination of pre-rendered 2D backgrounds and real-time rendered 3D character models, such asThe Temple of Elemental Evil (2003) andTorment: Tides of Numenera (2017); and games which combine real-time rendered 3D backgrounds with hand-drawn 2D character sprites, such asFinal Fantasy Tactics (1997) andDisgaea: Hour of Darkness (2003).
One advantage of top-downoblique projection over other near-isometric perspectives, is that objects fit more snugly within non-overlapping square graphical tiles, thereby potentially eliminating the need for an additionalZ-order in calculations, and requiring fewer pixels.
| This sectiondoes notcite anysources. Please helpimprove this section byadding citations to reliable sources. Unsourced material may be challenged andremoved.(December 2024) (Learn how and when to remove this message) |
One of the most common problems with programming games that use isometric (or more likely dimetric) projections is the ability to map between events that happen on the 2D plane of the screen and the actual location in the isometric space, called world space. A common example is picking the tile that lies right under the cursor when a user clicks. One such method is using the samerotation matrices that originally produced the isometric view in reverse to turn a point in screen coordinates into a point that would lie on the game board surface before it was rotated. Then, the world x and y values can be calculated by dividing by the tile width and height.
Another way that is less computationally intensive and can have good results if the method is called on every frame, rests on the assumption that a square board was rotated by 45 degrees and then squashed to be half its original height. A virtual grid is overlaid on the projection as shown on the diagram, with axes virtual-x and virtual-y. Clicking any tile on the central axis of the board where (x, y) = (tileMapWidth / 2, y), will produce the same tile value for both world-x and world-y which in this example is 3 (0 indexed). Selecting the tile that lies one position on the right on the virtual grid, actually moves one tile less on the world-y and one tile more on the world-x. This is the formula that calculates world-x by taking the virtual-y and adding the virtual-x from the center of the board. Likewise world-y is calculated by taking virtual-y and subtracting virtual-x. These calculations measure from the central axis, as shown, so the results must be translated by half the board. For example, in theC programming language:
floatvirtualTileX=screenx/virtualTileWidth;floatvirtualTileY=screeny/virtualTileHeight;// some display systems have their origin at the bottom left while the tile map at the top left, so we need to reverse yfloatinverseTileY=numberOfTilesInY-virtualTileY;floatisoTileX=inverseTileY+(virtualTileX-numberOfTilesInX/2);floatisoTileY=inverseTileY-(virtualTileX-numberOfTilesInY/2);
This method might seem counter intuitive at first since the coordinates of a virtual grid are taken, rather than the original isometric world, and there is no one-to-one correspondence between virtual tiles and isometric tiles. A tile on the grid will contain more than one isometric tile, and depending on where it is clicked it should map to different coordinates. The key in this method is that the virtual coordinates are floating point numbers rather than integers. A virtual-x and y value can be (3.5, 3.5) which means the center of the third tile. In the diagram on the left, this falls in the third tile on the y in detail. When the virtual-x and y must add up to 4, the world x will also be 4.
It was a big challenge because all of the Baldur's Gate original assets like the 3D models that make up these sprites, the 3D models for the levels in the original game, these archives were lost.
