3d and 2.5d
December 30, 2002 02:09 AM
I often hear people say this game is true 3d and that game is not true 3d but only 2.5d. Who can give me more details of the differences of real 3d and 2.5d?
thanks.
151
December 30, 2002 02:51 AM
2.5D game engines = Doom, Duke3D (AKA Build), even the older Wolfenstien 3D engine.
3D game engines = Quake, Unreal, pretty much every engine now available.
Wolfenstien used something like a 2D top-down style map sorta like what you would see in a old NES game...basicly a 2D array, with each cell containing info about wall textures...it then ''raycast'' to make those walls appear on screen.
Doom stored a collection of 2D lines in structure called a BSP-tree (Binary Space Partition)...each line segment contained info about wall textureas well as info about floor and ceiling hights.
Duke 3D...while simular to Doom...stored a collection of "sectors" (area defined by a series of connected line segments)...the engine could have sloped floors and ceilings...as well as share the floor or ceiling with another identicaly shaped and sized sector to allow rooms over rooms...it also treated such constructs...and the joining walls between sectors as "portals"...this engine is considered the most advanced of all the 2.5D engines because all of this....but all 2.5D engines shared one trait, the walls were uniformly vertical at all times (which put limitations on the type of envirement the games could take place in).
Quake...also used a BSP-tree to store the levels (much like Doom), however the levels were designed as complete 3D objects...as there was no need for the "trickery" associated with 2.5D engines to seem fully 3D.
Unreal is simular to Quake...and many of the newer engines have dropped BSP-trees in favor of Octrees, and or hybread systems (3D portal systems crossed with hightfield systems, for example)
But the main difference is that 2.5D engines use some sort of "trickery" to generate the impression of a 3D gameworld.
3D game engines = Quake, Unreal, pretty much every engine now available.
Wolfenstien used something like a 2D top-down style map sorta like what you would see in a old NES game...basicly a 2D array, with each cell containing info about wall textures...it then ''raycast'' to make those walls appear on screen.
Doom stored a collection of 2D lines in structure called a BSP-tree (Binary Space Partition)...each line segment contained info about wall textureas well as info about floor and ceiling hights.
Duke 3D...while simular to Doom...stored a collection of "sectors" (area defined by a series of connected line segments)...the engine could have sloped floors and ceilings...as well as share the floor or ceiling with another identicaly shaped and sized sector to allow rooms over rooms...it also treated such constructs...and the joining walls between sectors as "portals"...this engine is considered the most advanced of all the 2.5D engines because all of this....but all 2.5D engines shared one trait, the walls were uniformly vertical at all times (which put limitations on the type of envirement the games could take place in).
Quake...also used a BSP-tree to store the levels (much like Doom), however the levels were designed as complete 3D objects...as there was no need for the "trickery" associated with 2.5D engines to seem fully 3D.
Unreal is simular to Quake...and many of the newer engines have dropped BSP-trees in favor of Octrees, and or hybread systems (3D portal systems crossed with hightfield systems, for example)
But the main difference is that 2.5D engines use some sort of "trickery" to generate the impression of a 3D gameworld.
My deviantART: http://msw.deviantart.com/
122
December 30, 2002 10:47 PM
quote: Original post by cosey
I often hear people say this game is true 3d and that game is not true 3d but only 2.5d. Who can give me more details of the differences of real 3d and 2.5d?
thanks.
2D yet 3D. Looks like 3D but then its 2D. Half way to 3D, but still 2D. BAM! 2.5D
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