'===========================================================================
' Subject: 3D ENGINE W/TEXTURE MAPPING       Date: 11-01-96 (00:00)       
' Author:  Victor Woeltjen                   Code: QB, QBasic, PDS        
' Origin:  www.trenham.demon.co.uk/threed  Packet: GRAPHICS.ABC
'===========================================================================
'This is the complete txtreng.bas file. I switched over to NetScape's
'USENET thingy, and it let me attach the whole file. Sorry about all the
'other pieces, it took me a while to think of trying NS.
'
'Anyway, this engine is slow, but it does add simple textures. I'm sure
'some intelligent person out there could speed it up, but that person
'sure as hell ain't me.
'
'I in no way am responsible for the engine itself; all I added was the
'textures(and I changed the background a bit, but, it's still mostly
'someone else's freeware program).
'
'Victor Woeltjen, "Pissant"
'

' note from Peter Cooper (peco@trenham.demon.co.uk)
' -  this is very very slow but it works
'    compile it for speed, you can download compiled version from my
'    web site


DECLARE SUB CreateBackground ()
DECLARE SUB GetKeypress (Keycode%)

CONST UpArrow = -72, DnArrow = -80, LArrow = -75, RArrow = -77

RANDOMIZE TIMER
DIM Grid%(1 TO 12, 1 TO 12)
DIM STable!(0 - 31 TO 360 + 32), CTable!(0 - 31 TO 360 + 32)
DIM Textures(1 TO 15, 1 TO 4, 1 TO 30)
PX! = 9: PY! = 11    'the starting coordinates of the player's location
Stride! = 3          'the distance covered in one "step" by the player
                     '   by pressing the up or down arrow keys
Heading% = 0         'the heading of the player (in degrees)
Turn% = 5            'number of degrees of rotation produced by
                     '   pressing the right or left arrow keys

FOR Y% = 1 TO 12
  FOR X% = 1 TO 12
    READ Grid%(X%, Y%)
  NEXT
NEXT

FOR TexturesL = 1 TO 15
FOR TexY% = 1 TO 30
FOR TexX% = 1 TO 4
    READ Textures(TexturesL, TexX%, TexY%)
NEXT
NEXT
NEXT

Factor! = (ATN(1) * 8) / 360
FOR A% = 0 TO 359
  Angle! = CSNG(A%) * Factor!
  STable!(A%) = SIN(Angle!) * .1
  CTable!(A%) = COS(Angle!) * .1
NEXT
FOR A% = -31 TO -1
  STable!(A%) = STable!(A% + 360)
  CTable!(A%) = CTable!(A% + 360)
NEXT
FOR A% = 360 TO 360 + 32
  STable!(A%) = STable!(A% - 360)
  CTable!(A%) = CTable!(A% - 360)
NEXT

SCREEN 7, , 0, 0
PRINT
PRINT
PRINT "            RAYCASTER DEMO"
PRINT
PRINT "      UP ARROW........Move Forward"
PRINT "      DOWN ARROW......Move Backward"
PRINT "      RIGHT ARROW.....Turn Right"
PRINT "      LEFT ARROW......Turn Left"
PRINT
PRINT
PRINT "            Please wait...";

CALL CreateBackground
BEEP
LOCATE , 1
PRINT "        Press any key to begin...";
DO WHILE LEN(INKEY$): LOOP: DO UNTIL LEN(INKEY$): LOOP

ViewPg% = 0: WorkPg% = 1: BG1% = 2: BG2% = 3
SCREEN , , WorkPg%, ViewPg%
GOSUB ComputeView

DO 'Main loop
CALL GetKeypress(Keycode%)
SELECT CASE Keycode%
  CASE LArrow
    Heading% = (Heading% + Turn%) MOD 360
    GOSUB ComputeView
  CASE RArrow
    Heading% = (Heading% + (360 - Turn%)) MOD 360
    GOSUB ComputeView
  CASE UpArrow
    NewPX! = PX! - (STable!(Heading%) * Stride!)
    NewPY! = PY! - (CTable!(Heading%) * Stride!)
    IF Grid%(NewPX!, NewPY!) = 0 THEN
      PX! = NewPX!: PY! = NewPY!
      GOSUB ComputeView
    ELSE 'tried to walk through a wall
      SOUND 80, 1
    END IF
  CASE DnArrow
    NewPX! = PX! + (STable!(Heading%) * Stride!)
    NewPY! = PY! + (CTable!(Heading%) * Stride!)
    IF Grid%(NewPX!, NewPY!) = 0 THEN
      PX! = NewPX!: PY! = NewPY!
      GOSUB ComputeView
    ELSE 'tried to walk through a wall
      SOUND 80, 1
    END IF
  CASE 27
    EXIT DO
  CASE ELSE
    BEEP
  END SELECT
LOOP
SCREEN 0: WIDTH 80, 25
END

ComputeView:
PCOPY BG1%, WorkPg%: SWAP BG1%, BG2%
X1% = 0
FOR A% = Heading% + 32 TO Heading% - 31 STEP -1
  StepX! = STable!(A%): StepY! = CTable!(A%)
  XX! = PX!: YY! = PY!
  L% = 0
  DO
    XX! = XX! - StepX!: YY! = YY! - StepY!
    L% = L% + 1
    K% = Grid%(XX!, YY!)
  LOOP UNTIL K%
  DD% = 900 \ L%
  H% = DD% + DD%
  DT% = 100 - DD%
  ymoves = 0
  FOR Y = DT% TO DT% + H% STEP (H%) / 30
  ymoves = ymoves + 1
  FOR X = 1 TO 4
    IF ymoves > 30 THEN ymoves = 30
    LINE (X1% + X, DT% + ((ymoves - 1) * (H%) / 30))-(X1% + X + 1, DT% + ((ymoves) * (H%) / 30)), Textures(K%, X, ymoves), B
  NEXT
  NEXT
  'LINE (X1%, DT%)-STEP(4, H%), K%, BF
  X1% = X1% + 5
NEXT
SWAP WorkPg%, ViewPg%
SCREEN , , WorkPg%, ViewPg%
RETURN

' Level data
DATA  9,  1,  9,  1,  1,  1,  1,  1,  1,  1,  9,  1
DATA  1,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  9
DATA  9,  0,  2, 10,  0,  0,  0,  0,  0, 0,  0,  1
DATA  1,  0, 10,  2,  0,  0,  0,  0,  0,  0,  0,  9
DATA  9,  0,  0,  0,  0,  5,  0,  0,  0, 0,  0,  1
DATA  1,  0,  0,  0,  0,  4,  0,  0,  0,  0,  0,  9
DATA  9,  0,  0,  0,  0,  6,  0,  0,  0,  0,  0,  1
DATA  1,  0, 13,  0,  0,  4,  0,  0,  0, 12,  0,  9
DATA  9,  0,  5,  0,  0,  5,  0,  0,  0,  0,  0,  1
DATA  1,  0, 13,  0,  0,  0,  0,  0,  0, 12,  0,  9
DATA  9,  0,  5,  0,  0,  0,  0,  0,  0,  4,  0,  1
DATA  1,  9,  1,  9,  1,  9,  1,  9,  1,  9,  1,  9

'Texture data
'Text. 1
DATA 0, 8, 0, 0
DATA 8, 7, 8,
DATA 7, 7, 7, 8
DATA 7, 7, 7, 8
DATA 8, 8, 8, 0
DATA 8, 7,8,0
DATA 8, 7,8,0
DATA 8, 7,8,0
DATA 8, 7,8,0
DATA 8, 7,8,0
DATA 8, 7,8,0
DATA 8, 7,8,0
DATA 8, 8,8,8
DATA 7, 7,7,7
DATA 8, 8,8,8
DATA 8, 7,8,0
DATA 8, 7,8,0
DATA 8, 7,8,0
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DATA 8, 7,8,0
DATA 8, 7,8,0
DATA 8, 7,8,0
DATA 8, 7, 8, 0
DATA 8, 7, 8,2
DATA 8, 2, 8, 2
DATA 2, 10, 2, 2
DATA 2, 2, 10, 2
DATA 2, 2, 2, 2
'Text. 2
DATA 8, 8, 8, 8
DATA 8, 8, 8, 8
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DATA 7, 7, 7, 7
DATA 7, 15, 7, 15
DATA 15, 15, 15, 15
DATA 15, 15, 15, 15
DATA 15, 15, 15, 15
DATA 15, 15, 15, 15
DATA 15, 15, 15, 15
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DATA 7, 15, 7, 15
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'Text. 3
DATA 8, 8, 8, 8
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DATA 7, 15, 7, 15
DATA 15, 15, 15, 15
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DATA 15, 15, 15, 15
DATA 15, 15, 15, 15
DATA 15, 15, 15, 15
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DATA 15, 15, 15, 15
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DATA 15, 15, 15, 15
DATA 15, 15, 15, 15
DATA 15, 15, 15, 15
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DATA 15, 15, 15, 15
DATA 15, 15, 15, 15
DATA 15, 15, 15, 15
DATA 15, 15, 15, 15
DATA 7, 15, 7, 15
DATA 7, 7, 7, 7
DATA 8, 7, 8, 7
DATA 8, 8, 8, 8
DATA 8, 8, 8, 8
'Text. 4
DATA 4, 4, 4, 4
DATA 4, 8, 4, 8
DATA 8, 7, 8, 7
DATA 7, 7, 7, 7
DATA 7, 15, 7, 15
DATA 15, 15, 15, 15
DATA 15, 15, 15, 15
DATA 15, 15, 15, 15
DATA 15, 15, 15, 15
DATA 15, 15, 15, 15
DATA 15, 15, 15, 15
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DATA 15, 15, 15, 15
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DATA 15, 15, 15, 15
DATA 15, 15, 15, 15
DATA 15, 15, 15, 15
DATA 15, 15, 15, 15
DATA 7, 15, 7, 15
DATA 7, 7, 7, 7
DATA 8, 7, 8, 7
DATA 4, 8, 4, 8
DATA 4, 4, 4, 4
'Text. 5
DATA 4, 8, 4, 8
DATA 8, 8, 8, 8
DATA 8, 7, 8, 7
DATA 7, 7, 7, 7
DATA 7, 15, 7, 15
DATA 15, 15, 15, 15
DATA 15, 15, 15, 15
DATA 15, 15, 15, 15
DATA 15, 15, 15, 15
DATA 15, 15, 15, 15
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DATA 15, 15, 15, 15
DATA 15, 15, 15, 15
DATA 15, 15, 15, 15
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DATA 15, 15, 15, 15
DATA 15, 15, 15, 15
DATA 15, 15, 15, 15
DATA 15, 15, 15, 15
DATA 15, 15, 15, 15
DATA 15, 15, 15, 15
DATA 15, 15, 15, 15
DATA 15, 15, 15, 15
DATA 15, 15, 15, 15
DATA 7, 15, 7, 15
DATA 7, 7, 7, 7
DATA 8, 7, 8, 7
DATA 8, 8, 8, 8
DATA 8, 4, 8, 4
'Text. 6
DATA 4, 6, 4, 6
DATA 4, 4, 4, 4
DATA 8, 4, 8, 4
DATA 7, 7, 7, 7
DATA 7, 15, 7, 15
DATA 15, 15, 15, 15
DATA 15, 15, 15, 15
DATA 15, 15, 15, 15
DATA 15, 15, 15, 15
DATA 15, 15, 15, 15
DATA 15, 15, 15, 15
DATA 15, 15, 15, 15
DATA 15, 15, 15, 15
DATA 15, 15, 15, 15
DATA 15, 15, 15, 15
DATA 15, 15, 15, 15
DATA 15, 15, 15, 15
DATA 15, 15, 15, 15
DATA 15, 15, 15, 15
DATA 15, 15, 15, 15
DATA 15, 15, 15, 15
DATA 15, 15, 15, 15
DATA 15, 15, 15, 15
DATA 15, 15, 15, 15
DATA 15, 15, 15, 15
DATA 7, 15, 7, 15
DATA 7, 7, 7, 7
DATA 4, 7, 4, 7
DATA 4, 4, 4, 4
DATA 4, 6, 4, 6
'Text. 7
DATA 8, 8, 8, 8
DATA 8, 8, 8, 8
DATA 8, 7, 8, 7
DATA 7, 7, 7, 7
DATA 7, 15, 7, 15
DATA 15, 15, 15, 15
DATA 15, 15, 15, 15
DATA 15, 15, 15, 15
DATA 15, 15, 15, 15
DATA 15, 15, 15, 15
DATA 15, 15, 15, 15
DATA 15, 15, 15, 15
DATA 15, 15, 15, 15
DATA 15, 15, 15, 15
DATA 15, 15, 15, 15
DATA 15, 15, 15, 15
DATA 15, 15, 15, 15
DATA 15, 15, 15, 15
DATA 15, 15, 15, 15
DATA 15, 15, 15, 15
DATA 15, 15, 15, 15
DATA 15, 15, 15, 15
DATA 15, 15, 15, 15
DATA 15, 15, 15, 15
DATA 15, 15, 15, 15
DATA 7, 15, 7, 15
DATA 7, 7, 7, 7
DATA 8, 7, 8, 7
DATA 8, 8, 8, 8
DATA 8, 8, 8, 8
'Text. 8
DATA 8, 8, 8, 8
DATA 8, 8, 8, 8
DATA 8, 7, 8, 7
DATA 7, 7, 7, 7
DATA 7, 15, 7, 15
DATA 15, 15, 15, 15
DATA 15, 15, 15, 15
DATA 15, 15, 15, 15
DATA 15, 15, 15, 15
DATA 15, 15, 15, 15
DATA 15, 15, 15, 15
DATA 15, 15, 15, 15
DATA 15, 15, 15, 15
DATA 15, 15, 15, 15
DATA 15, 15, 15, 15
DATA 15, 15, 15, 15
DATA 15, 15, 15, 15
DATA 15, 15, 15, 15
DATA 15, 15, 15, 15
DATA 15, 15, 15, 15
DATA 15, 15, 15, 15
DATA 15, 15, 15, 15
DATA 15, 15, 15, 15
DATA 15, 15, 15, 15
DATA 15, 15, 15, 15
DATA 7, 15, 7, 15
DATA 7, 7, 7, 7
DATA 8, 7, 8, 7
DATA 8, 8, 8, 8
DATA 8, 8, 8, 8
'Text. 9
DATA 8, 8, 8, 8
DATA 8, 8, 8, 8
DATA 8, 7, 8, 7
DATA 7, 7, 7, 7
DATA 7, 15, 7, 15
DATA 15, 15, 15, 15
DATA 15, 15, 15, 15
DATA 15, 15, 15, 15
DATA 15, 15, 15, 15
DATA 15, 15, 15, 15
DATA 15, 15, 15, 15
DATA 15, 15, 15, 15
DATA 15, 15, 15, 15
DATA 15, 15, 15, 15
DATA 15, 15, 15, 15
DATA 15, 15, 15, 15
DATA 15, 15, 15, 15
DATA 15, 15, 15, 15
DATA 15, 15, 15, 15
DATA 15, 15, 15, 15
DATA 15, 15, 15, 15
DATA 15, 15, 15, 15
DATA 15, 15, 15, 15
DATA 15, 15, 15, 15
DATA 15, 15, 15, 15
DATA 7, 15, 7, 15
DATA 7, 7, 7, 7
DATA 8, 7, 8, 7
DATA 8, 8, 8, 8
DATA 8, 8, 8, 8
'Text. 10
DATA 8, 8, 8, 8
DATA 8, 8, 8, 8
DATA 8, 7, 8, 7
DATA 7, 7, 7, 7
DATA 7, 15, 7, 15
DATA 15, 15, 15, 15
DATA 15, 15, 15, 15
DATA 15, 15, 15, 15
DATA 15, 15, 15, 15
DATA 15, 15, 15, 15
DATA 15, 15, 15, 15
DATA 15, 15, 15, 15
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DATA 15, 15, 15, 15
DATA 15, 15, 15, 15
DATA 15, 15, 15, 15
DATA 15, 15, 15, 15
DATA 15, 15, 15, 15
DATA 15, 15, 15, 15
DATA 15, 15, 15, 15
DATA 15, 15, 15, 15
DATA 15, 15, 15, 15
DATA 15, 15, 15, 15
DATA 15, 15, 15, 15
DATA 15, 15, 15, 15
DATA 7, 15, 7, 15
DATA 7, 7, 7, 7
DATA 8, 7, 8, 7
DATA 8, 8, 8, 8
DATA 8, 8, 8, 8
'Text. 11
DATA 8, 8, 8, 8
DATA 8, 8, 8, 8
DATA 8, 7, 8, 7
DATA 7, 7, 7, 7
DATA 7, 15, 7, 15
DATA 15, 15, 15, 15
DATA 15, 15, 15, 15
DATA 15, 15, 15, 15
DATA 15, 15, 15, 15
DATA 15, 15, 15, 15
DATA 15, 15, 15, 15
DATA 15, 15, 15, 15
DATA 15, 15, 15, 15
DATA 15, 15, 15, 15
DATA 15, 15, 15, 15
DATA 15, 15, 15, 15
DATA 15, 15, 15, 15
DATA 15, 15, 15, 15
DATA 15, 15, 15, 15
DATA 15, 15, 15, 15
DATA 15, 15, 15, 15
DATA 15, 15, 15, 15
DATA 15, 15, 15, 15
DATA 15, 15, 15, 15
DATA 15, 15, 15, 15
DATA 7, 15, 7, 15
DATA 7, 7, 7, 7
DATA 8, 7, 8, 7
DATA 8, 8, 8, 8
DATA 8, 8, 8, 8
'Text. 12
DATA 8, 8, 8, 8
DATA 8, 8, 8, 8
DATA 8, 7, 8, 7
DATA 7, 7, 7, 7
DATA 7, 15, 7, 15
DATA 15, 15, 15, 15
DATA 15, 15, 15, 15
DATA 15, 15, 15, 15
DATA 15, 15, 15, 15
DATA 15, 15, 15, 15
DATA 15, 15, 15, 15
DATA 15, 15, 15, 15
DATA 15, 15, 15, 15
DATA 15, 15, 15, 15
DATA 15, 15, 15, 15
DATA 15, 15, 15, 15
DATA 15, 15, 15, 15
DATA 15, 15, 15, 15
DATA 15, 15, 15, 15
DATA 15, 15, 15, 15
DATA 15, 15, 15, 15
DATA 15, 15, 15, 15
DATA 15, 15, 15, 15
DATA 15, 15, 15, 15
DATA 15, 15, 15, 15
DATA 7, 15, 7, 15
DATA 7, 7, 7, 7
DATA 8, 7, 8, 7
DATA 8, 8, 8, 8
DATA 8, 8, 8, 8
'Text. 13
DATA 8, 8, 8, 8
DATA 8, 8, 8, 8
DATA 8, 7, 8, 7
DATA 7, 7, 7, 7
DATA 7, 15, 7, 15
DATA 15, 15, 15, 15
DATA 15, 15, 15, 15
DATA 15, 15, 15, 15
DATA 15, 15, 15, 15
DATA 15, 15, 15, 15
DATA 15, 15, 15, 15
DATA 15, 15, 15, 15
DATA 15, 15, 15, 15
DATA 15, 15, 15, 15
DATA 15, 15, 15, 15
DATA 15, 15, 15, 15
DATA 15, 15, 15, 15
DATA 15, 15, 15, 15
DATA 15, 15, 15, 15
DATA 15, 15, 15, 15
DATA 15, 15, 15, 15
DATA 15, 15, 15, 15
DATA 15, 15, 15, 15
DATA 15, 15, 15, 15
DATA 15, 15, 15, 15
DATA 7, 15, 7, 15
DATA 7, 7, 7, 7
DATA 8, 7, 8, 7
DATA 8, 8, 8, 8
DATA 8, 8, 8, 8
'Text. 14
DATA 8, 8, 8, 8
DATA 8, 8, 8, 8
DATA 8, 7, 8, 7
DATA 7, 7, 7, 7
DATA 7, 15, 7, 15
DATA 15, 15, 15, 15
DATA 15, 15, 15, 15
DATA 15, 15, 15, 15
DATA 15, 15, 15, 15
DATA 15, 15, 15, 15
DATA 15, 15, 15, 15
DATA 15, 15, 15, 15
DATA 15, 15, 15, 15
DATA 15, 15, 15, 15
DATA 15, 15, 15, 15
DATA 15, 15, 15, 15
DATA 15, 15, 15, 15
DATA 15, 15, 15, 15
DATA 15, 15, 15, 15
DATA 15, 15, 15, 15
DATA 15, 15, 15, 15
DATA 15, 15, 15, 15
DATA 15, 15, 15, 15
DATA 15, 15, 15, 15
DATA 15, 15, 15, 15
DATA 7, 15, 7, 15
DATA 7, 7, 7, 7
DATA 8, 7, 8, 7
DATA 8, 8, 8, 8
DATA 8, 8, 8, 8
'Text. 15
DATA 8, 8, 8, 8
DATA 8, 8, 8, 8
DATA 8, 7, 8, 7
DATA 7, 7, 7, 7
DATA 7, 15, 7, 15
DATA 15, 15, 15, 15
DATA 15, 15, 15, 15
DATA 15, 15, 15, 15
DATA 15, 15, 15, 15
DATA 15, 15, 15, 15
DATA 15, 15, 15, 15
DATA 15, 15, 15, 15
DATA 15, 15, 15, 15
DATA 15, 15, 15, 15
DATA 15, 15, 15, 15
DATA 15, 15, 15, 15
DATA 15, 15, 15, 15
DATA 15, 15, 15, 15
DATA 15, 15, 15, 15
DATA 15, 15, 15, 15
DATA 15, 15, 15, 15
DATA 15, 15, 15, 15
DATA 15, 15, 15, 15
DATA 15, 15, 15, 15
DATA 15, 15, 15, 15
DATA 7, 15, 7, 15
DATA 7, 7, 7, 7
DATA 8, 7, 8, 7
DATA 8, 8, 8, 8
DATA 8, 8, 8, 8

DEFINT A-Z
DEFSNG A-Z

SUB CreateBackground

SCREEN , , 2, 0: CLS
' Sky
LINE (0, 0)-(319, 99), 0, BF
' Moon (Prev. a Sun)
CIRCLE (50, 30), 10, 8: PAINT (50, 30), 14, 8
'CIRCLE (53, 27), 2, 8: PAINT (53, 27), 8, 8
CIRCLE (43, 29), 10, 0: PAINT (43, 29), 0, 0
' Clouds moved after moon so they would overlap it
FOR Cnt% = 1 TO 10
  X% = INT(RND * 320)
  Y% = INT(RND * 80) + 10
  R% = INT(RND * 50)
  AR! = RND / 10
  CIRCLE (X%, Y%), R%, 15, , , AR!: PAINT (X%, Y%), 15
NEXT

 'Building (gray)
LINE (200, 20)-(220, 15), 8
LINE (220, 15)-(240, 20), 8
LINE (200, 20)-(200, 99), 8
LINE (240, 20)-(240, 99), 8
LINE (200, 99)-(240, 99), 8
PAINT (220, 50), 8
FOR Cnt% = 1 TO 20 ' Lights
  PSET (INT(RND * 38 + 201), INT(RND * 80 + 20)), 14
NEXT
LINE (200, 20)-(220, 15), 0 ' Building (border)
LINE (220, 15)-(240, 20), 0
LINE (219, 15)-(219, 99), 0
LINE (200, 20)-(200, 99), 0
LINE (240, 20)-(240, 99), 0
PCOPY 2, 3
FOR Y% = 100 TO 199
  FOR X% = 0 TO 319
    IF RND AND 1 THEN PSET (X%, Y%), 8
  NEXT
NEXT

SCREEN , , 3, 0
FOR Y% = 100 TO 199
  FOR X% = 0 TO 319
    IF RND AND 1 THEN PSET (X%, Y%), 8
  NEXT
NEXT

SCREEN , , 0, 0

END SUB

DEFINT A-Z
SUB GetKeypress (Keycode%)
DO: Ky$ = INKEY$: LOOP UNTIL LEN(Ky$)
Keycode% = ASC(Ky$): IF Keycode% = 0 THEN Keycode% = -ASC(MID$(Ky$, 2, 1))

END SUB