Forum archive

BUILD & DOOM technology comparison

Return to forum index

• etko at 2005-02-04 22:38
  Hi,
  
  I've been with DooM, DUKE3D and BLOOD for several years now :).
  I'm just investigating some concepts behind this two engines.
  
  This is what I found out:
  
  BOTH are 2.5D sector based engines, support slopes and got OpenGL, HiRes texture and MD2 support.
  
  (Z)DOOM
  - uses BSP tree to store sector/level information, thus levels are static
  - moving map parts are possible only by using zdoom/hexen polyobj hack and aren't real sectors
  - doesn't have "native" editor, mapper is unable to preview level realtime
  - doesn't support sector over sector mapping
  - zdoom has acquired powerfull ACS sripting language and sector capabilities
  
  BUILD
  - uses some diffren't algorithm for visibility calculation (which one) ?
  - map is completely dynamic, any sector can be moved
  - has "native" editor with online preview
  - supports sector over sector scheme when certain conditions are met
  - has quite obscure sripting system
  
  My question is mainly, what algorithm current OpenGL BUILD incarnation uses?
  My second question is, are there any other differences?
  
  Thank you
• maniac1701 at 2005-02-05 05:15
  You said that doom supports slopes. This isn't true doom (or at least commercial versions including doom2 v1.9) didn't support them. You could approximate them by having tons of close by sectors and having the height difference changed by only 1 unit, but this never looked as good as the real thing.
  
  You also said that doom can't have a 3d preview in a map editor. this isn't true either. i use a program called doom builder by code imp that has a open gl 3d preview that looks EXACTLY like the game. in fact, you can move in any direction and i found several areas in my maps that had problems that you wouldn't normally see using this method. it also supports realtime 3d texture alignment. this makes it easy to tweek the details. also like build it will let you move the floor and ceiling up and down in real time as well. if your interested here is the link http://www.codeimp.com/builder_info.php
  
  As your your question of which algorythem does this build port use to support open gl?
  the answer is pollymost, this was designed by the engine's original author ken silverman.
  
  As for other differences Im not sure.
• )))000((( at 2005-02-05 09:35
  Original Duke Nukem Engine is much more supperior compered to the Original Doom Engine...
• etko at 2005-02-05 12:22
  I've been doing maps for DOOM since cca 1994, and was modifing BLOOD and DUKE. (I had even tried to import data from DOOM into DUKE and had to copy palette, genrate some translucency tables etc.) I was faking open stairways with wallsprites and did all that silly stuff you doo when you're kid. So I understand differences from advanced users point of view :), I just want to know how the data in the BUILD engine are organised in memory and how they are processed. I'm interested in "internal" engine differencies. In BUILD map is not BSP based so I'm just wondering how it's done. Sure I can look at the sources but I'm too dumb to understand it. I just want to hear from someone who understands the engine rendering process simple and comprehensive description of the algorithm used to parse and select visible sectors.
  
  I'm not interested in the past, but in the future of both technologies.
• maniac1701 at 2005-02-05 13:58
  i could be wrong cause i haven't looked at the src, but im guessing that duke uses z buffering.
  the idea is that you draw a bunch of triangles in any order but when drawing each pixel, you record the depth of each pixel and if the older pixel is closer then the newer one you discard it otherwise you draw it. its surperior to bsp in that all objects may move but it requires more calulations.
  
  considering that duke's engine shows about the same amount of detail as doom AND it was released several years later AND the secors can move this would be the only algorythm that would make any sence
• Awesoken at 2005-02-05 16:59

  im guessing that duke uses z buffering. ... this would be the only algorythm that would make any sence

  Nice try, but that's not even close. A z-buffer would have been way too slow on a 486. Speculation is almost always wrong when you don't do your homework. For hints on the inner workings of Build, please visit this thread:
  
  http://jonof.edgenetwork.org/forum/viewtopic.php?t=137
  
  Sorry, I don't know about the inner workings of Doom. I wouldn't want to speculate : P