ENGINE GENERATIONCompare two ways to turn a 2D plan into a first-person world

One ray walks a square grid for each screen column.

POSITION2.50, 1.50HEADING0 DEGRAYS / FRAME320SIGNALS0/3

Enter the archive and recover all three renderer signals.

TOP-DOWN WORLD / RAY FAN

SELECTED RAY#160

OFFSET: 0.10 DEG
RAW LENGTH: 12.500
PERP. DIST: 12.500
HIT CELL: 15,1
WALL TYPE: boundary stone
WALL FACE: X / VERTICAL
TEXTURE U: 0.477
GRID STEPS: 13

+5

W/S MOVE - A/D TURN - Q/E STRAFE - P PAUSE - N STEP DDA - R RESET

RAY CASTING ENGINE / 1992 PC

WOLFENSTEIN
RAYCASTER LAB

Walk through an original maze, then freeze the renderer. Every vertical screen strip comes from one ray crossing a flat grid until it finds a wall.

LIVE RAY TRACE

One column, five calculations

STRIP #160

01

SCREEN SAMPLE50.2% across frame

02

RAY ANGLE0.10 DEG

03

DDA GRID WALK0/13 cell boundaries revealed

04

DISTANCE12.500 raw - 12.500 perpendicular

05

WALL SCALE44.3 px high - texture 0.477

DDA jumps from one vertical or horizontal grid boundary to the next. The first occupied cell supplies the wall type, face, texture coordinate, and distance for this screen column.

QUICK EXPERIMENTS

Break one assumption at a time

TUNE THE RAYCASTER

Field of view60 DEGRay count320View distance18 tilesTexture resolution64 bandsMovement speed2.35xPerpendicular-distance correctionRemoves fisheye bending by scaling each raw ray by its angle from the camera center.Procedural wall texturesUses the wall hit coordinate to choose a vertical texture band.Distance and side shadingDarkens far walls and horizontal faces so the flat strips read as volume.Top-down ray fanShows sampled rays in the hidden 2D world model.

POSITION2.50, 5.00HEADING0 DEGSECTORSignal AtriumDRAW / REJECT7 / 11

Drag a vertex, tune a sector, or enter the freeform map with WASD.

FREEFORM LINEDEFS / DASHED P = PORTAL / GOLD = SELECTED

SELECTED LINEDEFarchive-portal

TYPE: TWO-SIDED PORTAL
VERTICES: v14 → v15
FRONT: Offset Gallery
BACK: Low Archive
SCREEN SPAN: 240–422 PX
PORTAL OPENING: 0.25–2.60 Z
BSP STEP: READY
CAMERA SIDE: —

W/S MOVE · A/D TURN · Q/E STRAFE · SPACE PAUSE · N STEP BSP · R RESET

1993 DOOM ENGINE TECHNOLOGY LAB

SECTORS,
SEGMENTS & BSP

Break the square grid. Drag angled walls, change room heights and light, walk through two-sided portals, then watch a BSP tree order projected wall segments and reject hidden work.

01–04 / FREEFORM WORLD

Vertices, linedefs, sectors and portals

16 V · 18 L

ANGLED LINEDEFS7not locked to the gridTWO-SIDED PORTALS2connect adjacent sectorsPROJECTED SPANS13each covers many pixelsDRAW COMMANDS7upper, middle or lower bands

EDIT A VERTEX

Vertex

X Y

INSPECT A LINEDEF

Linedef

FRONT SIDE: Offset Gallery
BACK SIDE: Low Archive
RESULT: OPEN PORTAL

SECTOR HEIGHT + LIGHT

Floor height0.25 ZCeiling height4 ZSector light0.65

Rooms preserve 1.60 units of headroom. Raising the active floor carries the camera with it.

PROJECTION CONTROLS

Horizontal FOV75 DEGNear clip plane0.05 UMovement speed3 U/S

THE ENGINE SWAP

Six assumptions replaced

01FREEFORM VERTICES

Walls can meet at any angle instead of occupying square tiles.

02HEIGHT SECTORS

Each region owns its floor, ceiling and fixed light level.

03PORTAL LINEDEFS

Two-sided walls reveal the height overlap between neighboring sectors.

04SEGMENT PROJECTION

One endpoint pair can cover many screen columns at once.

05BSP ORDERING

Partition planes create a deterministic front-to-back traversal.

06OCCLUSION CLIPPING

Covered spans reject farther walls before they reach the drawing stage.