Series
Wolfenstein
13 games, 1981–2019.
Games
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The series by yearMechanics
A marked cell changed from the game before. “Uses” means the game has the mechanic, with no variant recorded yet.
Every claim, by mechanic and game
| Concept | Wolfenstein 3D
1992 |
|---|
| Damage formula | uses |
| Hitscan | - A Wolfenstein 3D gun shot (
GunAttack) picks a target instead of tracing a bullet's path: it takes the nearest visible shootable actor within shootdelta (a tenth of the view's width) of the screen's center column and hits it if CheckLine returns true, which its header comment describes as "a straight line between the player and ob is unobstructed"; as written, the loop's second pass looks only for actors nearer than that one, so a blocked line is a miss (computed). The damage is a roll of US_RndT (0 to 255) by the larger of the x and y tile distances: under 2 tiles the roll / 4 (0 to 63), under 4 the roll / 6 (0 to 42), and farther a miss when a first roll / 12 is below the distance, otherwise a second roll / 6. Code - An enemy's shot in Wolfenstein 3D (
T_Shoot) traces no bullet either: when the shooter's area connects to the player's (areabyplayer) and CheckLine finds a clear line, it hits if a roll of US_RndT is below a chance of 256 less 16 per tile of distance, or less 8 per tile when the shooter isn't visible on the player's screen (FL_VISABLE), starting from 160 instead of 256 when the player's thrust this frame (thrustspeed) reached RUNSPEED (6,000); SS guards and bossobj bosses count two-thirds of the distance. A hit deals the roll >> 2 (0 to 63) under 2 tiles, >> 3 (0 to 31) under 4, and >> 4 (0 to 15) farther. Code - Because the player's thrust scales with the frame's tics, a Wolfenstein 3D player who only walks straight forward with the keyboard (5,250 units a tic) counts as running for
T_Shoot's lower hit chance (thrustspeed at least RUNSPEED, 6,000) on any frame that spans 2 or more tics, and only a 1-tic frame leaves that walk below it; thrustspeed sums every Thrust call, so a walk that also strafes (5,250 + 5,250) passes it even in 1 tic (computed). Code
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| Random number generator | - Wolfenstein 3D's random numbers come from
rndtable, a fixed table of 256 bytes: US_RndT adds 1 to one index, wraps it at 256, and returns that entry, and the file's comment calls it "John Carmack's table driven pseudo-random number generator". SetupGameLevel sets the index to 0 for each level of a demo being played or recorded, and otherwise to the low byte of DX from DOS's get-time call (int 21h, function 2Ch), the hundredths of a second, 0 to 99 (the atlas's reading of the DOS call). Code - Doom's
rndtable holds the same 256 values in the same order as Wolfenstein 3D's (compared entry by entry, computed); Doom walks it with two indices (prndindex for P_Random, rndindex for M_Random), where Wolfenstein 3D uses one (rndindex). Code
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| Raycasting | - John Carmack's notes to the Wolfenstein 3D source release say the game's "ray casting refresh architecture is still reasonably appropriate for the game", and that "a BSP based texture mapper could go faster, but ray casting was a lot simpler to do at the time". Developer
- Wolfenstein 3D finds its walls with one ray per column of the view:
AsmRefresh steps pixx from 0 up to viewwidth, aiming each ray at the view angle plus pixelangle[pixx], in angles of 3,600 to a turn (FINEANGLES), and CalcProjection sets each column's offset to the arctangent of its whole-pixel distance from the center (scaled by VIEWGLOBAL/viewwidth) over facedist, the focal length plus MINDIST, so the rays cross a flat projection plane at even spacing rather than fanning out at even angles (the last part computed). The two middle columns both get an offset of 0, though the loop's comment says it starts "1/2 pixel over". Code - Each Wolfenstein 3D ray walks the tile map, 64 by 64 tiles at most (
MAPSIZE), one grid line at a time: AsmRefresh alternates between the next vertical and the next horizontal grid line, taking whichever the ray crosses first, and steps by adding a tangent from finetangent (ystep or xstep) to the other coordinate's intercept; at each crossing it tests the tile beyond in tilemap, marking an empty one in spotvis, and the first nonzero tile ends the ray with a call to HitVertWall or HitHorizWall, or the door and pushwall code when the tile's top bit is set. Code - Wolfenstein 3D sizes each wall column by the hit point's distance along the facing, not along the ray:
CalcHeight takes the hit point's offset from the view point, which WallRefresh sets focallength behind the player, projects it onto the view direction with viewcos and viewsin (nx = gxt-gyt), raises it to at least mindist, and divides heightnumerator by nx>>8, which the code's comment calls the "perspective ratio". Measuring along the facing is what keeps a flat wall straight on screen instead of bowed (fisheye), the atlas's reading. Code
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| Running | - Wolfenstein 3D keeps no velocity for the player: each frame
ControlMovement zeroes thrustspeed, and Thrust moves the player straight through ClipMove by the frame's control value times MOVESCALE (150), or BACKMOVESCALE (100) backward. The keyboard sets that value to 35 a tic walking (BASEMOVE) or 70 running (RUNMOVE), times the frame's tics, so a walk moves 5,250 and a run 10,500 units a tic, with 65,536 units to a tile (TILEGLOBAL); Thrust clamps each move to MINDIST*2-1 (45,055), so those rates hold on frames of at most 8 tics walking or 4 running, and longer frames move less a tic. At the 70 tics a second of TickBase's comment a run is about 11.2 tiles a second (computed). Code
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| Strafe-running | |