This dusty diskette from ages past was sitting in my closet. "Danger," it says, with a skull.
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' Let's see if we can make us some 3D graphics! In Basic, Hehe.
DECLARE FUNCTION maxval% (v1%, v2%, limit%)
DECLARE FUNCTION minval% (v1%, v2%, v3%)
DECLARE SUB hline (x1%, x2%, y%, c%)
DECLARE FUNCTION min% (v1%, v2%, v3%)
DECLARE FUNCTION max% (v1%, v2%, v3%)
DECLARE SUB pal ()
DECLARE SUB pixel (x%, y%, c%)
DEFINT A-Z 'set default var type to int 'cos it's my fav.
'$STATIC 'use static arrays
CLS 'clear the screen. duh
SCREEN 13 'initialize screen mode 13 (0x013 (19) 4 real)
CONST SCRX = 320 'sort of like #define so I can use SCRX/Y instead
CONST SCRY = 200 'of the actual #'s in case the width changes, etc.
CONST CLRS = 255 'ditto w/ color depth
CONST HLFX = 160 'half the screen width
CONST HLFY = 100 'half screen height (both use lots, should save calc.)
CONST PI = 3.141592654# 'close enuf
CONST VIEWRANGE = 16 'how far before fade to blackness
CONST MSZE = 16 'size of the map (x & y are = )
CONST MHGT = 4 'height of random mountains (TEMP)
CONST MININT = -32768 'lowest possible integer
CONST CONTRAST = 20 'multiplied by light values
CONST AMBIENT = 50 'added to light values
LOCATE 1, 1: COLOR 200: PRINT "Loading"
' make lookup-tables
DIM sine(0 TO 255) AS SINGLE
DIM cosine(0 TO 255) AS SINGLE
FOR i = 0 TO 255
sine(i) = SIN(i) * PI / 200 'Convert rad to "hex"
cosine(i) = COS(i) * PI / 200 'Convert rad to "hex"
NEXT i
'Note to self: REMEMBER I'm using "hexians" (256) NOT degrees (360)
'Layout of the landscape. . . just some random sample data for now!
DIM land(1 TO MSZE, 1 TO MSZE) AS INTEGER 'array containing landscape
RANDOMIZE TIMER 'use timer to seed random
'# generator
FOR x = 1 TO MSZE
FOR y = 1 TO MSZE
land(x, y) = INT(RND * MHGT) 'fill w/ random data
NEXT y
NEXT x
'make a variable to hold edge buffers
TYPE edge
ls AS INTEGER
rs AS INTEGER
END TYPE
DIM edge(0 TO SCRY) AS edge
'. . . and make an gradiant green palette
OUT &H3C8, 0 ' tell port whole palette is coming (otherwise # of color)
FOR i = 0 TO 255
OUT &H3C9, 0 'red
OUT &H3C9, INT(i / 4) 'green
OUT &H3C9, 0 'blue
'Hahaha! I'll never use THIS command again,
'PALETTE i, INT(i / 4) * 256
NEXT i
' Initialize the player variale to hold info on player position
TYPE spot
x AS INTEGER 'x runs horizontally to player (pitch)
y AS INTEGER 'y runs out from player (roll)
z AS INTEGER 'z runs up and down (yaw) aka altitude
'I know these are not std. but they fit better w/ the flat map
END TYPE
DIM pov AS spot
DIM currentpoint AS spot ' used w/i the program loop
pov.x = 8
pov.y = -8
pov.z = 7
'temp
DIM points(1 TO MSZE, 1 TO MSZE) AS spot'uses x and y as screen co-ords & z as
'distance
DIM ver(1 TO 3) AS spot 'vertex: used for drawing polygons, x
'and y are co-ords & z is color
DIM tmp(1 TO 3) AS spot 'used w/ ver for sorting
BEEP
CLS
DO
a$ = INKEY$
SELECT CASE a$
CASE "a": pov.x = pov.x + 1: CLS
CASE "d": pov.x = pov.x - 1: CLS
CASE "w": pov.y = pov.y + 1: CLS
CASE "s": pov.y = pov.y - 1: CLS
CASE "e": pov.z = pov.z + 1: CLS
CASE "c": pov.z = pov.z - 1: CLS
CASE CHR$(27): SYSTEM
END SELECT
FOR x = 1 TO MSZE
FOR y = 1 TO MSZE
'in front of us
rely = y - pov.y
relx = x - pov.x
relz = land(x, y) - pov.z
IF rely > 0 AND ABS(relx) <= rely AND ABS(relz) <= rely THEN
points(x, y).y = HLFY - relz * HLFY / rely
points(x, y).x = HLFX - relx * HLFX / rely
'a^3 = b^3 + c^3 + d^3 to find z (pixel dist.)
points(x, y).z = (ABS(relz) ^ 3 + ABS(rely) ^ 3 + ABS(relx) ^ 3) ^ (1 / 3)
ELSE points(x, y).z = -1
IF points(x, y).y < 0 OR points(x, y).y > SCRY OR points(x, y).x < 0 OR points(x, y).x > SCRX OR points(x, y).z > VIEWRANGE THEN points(x, y).z = -1
END IF
NEXT y
NEXT x
FOR y = MSZE - 1 TO 1 STEP -1
FOR x = MSZE - 1 TO 1 STEP -1
'if the current point has not been flagged as offscreen, out of FOV, or not w/i range of VIEWRANGE (z=-1)
IF points(x, y).z >= 0 THEN
'seperate into two triangles
FOR p = 0 TO 1
'get points of tri.
IF p = 0 THEN
ver(1).x = points(x, y).x: ver(1).y = points(x, y).y: ver(1).z = points(x, y).z
ver(2).x = points(x, y + 1).x: ver(2).y = points(x, y + 1).y: ver(2).z = points(x, y + 1).z
ver(3).x = points(x + 1, y + 1).x: ver(3).y = points(x + 1, y + 1).y: ver(3).z = points(x + 1, y + 1).z
ELSE
'sides 1 & 3 are reversed so will be
'in same rotational order (this could
'be more efficient - swap lables)
ver(3).x = points(x, y).x: ver(3).y = points(x, y).y: ver(3).z = points(x, y).z
ver(1).x = points(x + 1, y + 1).x: ver(1).y = points(x + 1, y + 1).y: ver(1).z = points(x + 1, y + 1).z
'side 2 is other corner of square
ver(2).x = points(x + 1, y).x: ver(2).y = points(x + 1, y).y: ver(2).z = points(x + 1, y).z
END IF
'translate tri. so ver[1] is origin
'of tmp, w/ V2 & V3 as vectors
tmp(2).x = ver(2).x - ver(1).x
tmp(2).y = ver(2).y - ver(1).y
tmp(3).x = ver(3).x - ver(1).x
tmp(3).y = ver(3).y - ver(1).y
'if we are facing the polygon (uses
'vectors to find if c.clockwise)
IF tmp(2).x * tmp(3).y < tmp(3).x * tmp(2).y THEN
'sort ver[] tp-bt
GOSUB sort
'find tri. height
dy = ver(1).y - ver(3).y
'delta-y for short side 1
dy1 = ver(1).y - ver(2).y
'slope of long side
m! = (ver(3).x - ver(1).x) / dy
'find width at middle
midwidth = ver(2).x - (ver(1).x + (m! * dy1))
'if long side is on the left
'IF midwidth > 1 THEN
'if width is big enough to see
IF ABS(midwidth) > 1 THEN
'if height is big enough to see
IF dy > 1 THEN
'delta-y of short side 2
dy2 = ver(2).y - ver(3).y
'slope of short side 1 (clause prevents div by 0)
IF ABS(dy1) > 0 THEN m1! = (ver(2).x - ver(1).x) / dy1
'slope of short side 2 (clause prevents division by 0)
IF ABS(dy2) > 0 THEN m2! = (ver(3).x - ver(2).x) / dy2
'calculate the color
'colr = points(x, y).y - points(x + 1, y + 1).y + 30'VIEWRANGE - ver(1).z + 20
IF p = 0 THEN
colr = (land(x, y + 1) - (land(x, y) + land(x + 1, y + 1)) / 2) * CONTRAST + AMBIENT
ELSE
colr = ((land(x, y) + land(x + 1, y + 1)) / 2 - land(x + 1, y)) * CONTRAST + AMBIENT
END IF
FOR h = 0 TO dy
ypos = ver(1).y - h
IF h <= dy1 THEN
LINE (ver(1).x + (m! * h), ypos)-(ver(1).x + (m1! * h), ypos), colr
'xa = ver(1).x + (m! * h)
'xb = ver(1).x + (m1! * h)
'x1 = minval(xa, xb, 0)
'x2 = maxval(xa, xb, SCRX)
'hline x1, x2, ypos, colr
ELSE
LINE (ver(1).x + (m! * h), ypos)-(ver(2).x + (m2! * (h - dy1)), ypos), colr
'xa = ver(1).x + (m! * h)
'xb = ver(2).x + (m2! * h)
'x1 = minval(xa, xb, 0)
'x2 = maxval(xa, xb, SCRX)
'hline x1, x2, ypos, colr
END IF
NEXT h
END IF
END IF
'END IF
'if long side is on the right
'IF midwidth < -1 THEN
'END IF
'else is too thin to see
'LINE (ver(1).x, ver(1).y)-(ver(2).x, ver(2).y), 255'VIEWRANGE - ver(1).z
'LINE (ver(2).x, ver(2).y)-(ver(3).x, ver(3).y), 255'VIEWRANGE - ver(1).z
'LINE (ver(3).x, ver(3).y)-(ver(1).x, ver(1).y), 255'VIEWRANGE - ver(1).z
END IF
NEXT p
END IF
NEXT x
NEXT y
LOOP
sort:
'assign tmp the values of ver
FOR i = 1 TO 3
tmp(i).x = ver(i).x
tmp(i).y = ver(i).y
tmp(i).z = ver(i).z
NEXT i
'order them top to bottom [1st pnt]
flag = max(tmp(1).y, tmp(2).y, tmp(3).y)
'used to skip 3rd calculation
topflag = flag
'assign values to the first vertex
ver(1).x = tmp(flag).x: ver(1).y = tmp(flag).y: ver(1).z = tmp(flag).z
'make y lowest possible # 4 further compares
tmp(flag).y = MININT
'order top-bottom 2 (prev. top is now -32768)
flag = max(tmp(1).y, tmp(2).y, tmp(3).y)
'add to flag to find which of 3 is not used
topflag = topflag + flag
'assign values to the 2nd vertex
ver(2).x = tmp(flag).x: ver(2).y = tmp(flag).y: ver(2).z = tmp(flag).z
'use topflag to find last point in order
SELECT CASE topflag
CASE 3 'used 1 & 2
flag = 3
CASE 4 'used 1 & 3
flag = 2
CASE 5 'used 2 & 3
flag = 1
CASE ELSE 'just in case
BEEP
flag = 1
END SELECT
'assign values to the 3rd vertex
ver(3).x = tmp(flag).x: ver(3).y = tmp(flag).y: ver(3).z = tmp(flag).z
RETURN
SUB hline (x1, x2, y, c)
FOR i = x1 TO x2
pixel i, y, c
NEXT i
END SUB
''''''''''''''''
' Returns 1, 2, or 3, depending on which value: 1st, 2nd, or 3d is largest
FUNCTION max (v1, v2, v3)
r = 0
IF v1 >= v2 AND v1 >= v3 THEN r = 1
IF v2 >= v1 AND v2 >= v3 THEN r = 2
IF v3 >= v2 AND v3 >= v1 THEN r = 3
max = r
END FUNCTION
''''''''''''''''
' Returns the largest of the three values passed to it w/i limit
FUNCTION maxval (v1, v2, limit)
r = 0
IF v1 >= v2 THEN r = v1
IF v2 >= v1 THEN r = v2
IF r > limit THEN r = limit
maxval = r
END FUNCTION
''''''''''''''''
' Returns the smallest of the three values passed to it w/i limit
FUNCTION minval (v1, v2, limit)
r = 0
IF v1 <= v2 THEN r = v1
IF v2 <= v1 THEN r = v2
IF r < limit THEN r = limit
minval = r
END FUNCTION
'This SUB does the same thing as PSET only by writing directly to the video
'memory which *should* be much faster (Muahahaha!)
'
SUB pixel (x, y, c)
DEF SEG = &HA000 'A000h is where the video mem. starts in mode
'13h, which we're using
IF x < 0 OR x > SCRX THEN EXIT SUB 'make sure x is on the screen
IF y < 0 OR y > SCRY THEN EXIT SUB 'make sure y is on the screen
'(We do NOT want to be writing directly into
'memory somewhere we're not supposed to!)
IF c < 0 OR c > CLRS THEN EXIT SUB 'make sure c is w/i the color palette
y& = y 'needed to prevent overflow (where's an
'unsigned int when you need it?)
POKE y& * SCRX + x, c 'put c into the right spot offset from A000h
'(pixels go lt-rt, tp-bt in a linear fashion)
END SUB