' original upload code:- ?BRS931
' new uploda code LZW978
' Raycaster maze
' uses a simple ray casting technique (see lodev.org for tutorial) to draw
' vertical stripes down the graphics window.
' Each stripe is drawn to a size dependent upon the distance of the wall from the viewer.
' "Rays" are cast across a viewing plane in front of the viewer, from left to right.
' the height of the wall stripe depends on the distance of the wall from the viewer.
InitialSetUp:
' set up screen width and height
' values also used to determine the width and height of the "viewing plane"
' "size" is used to determine the width of each vertical line drawn.
' a smaller value makes the walls sharper, but draws slower (there are more lines)
' a larger value makes the walls blockier, but draws more quickly
'w = 511
'h = 384
w = 511
h = 384
size = 8
'intensity of light source. The lower the number the further you can see.
intensity = 50
GraphicsWindow.Width = w
GraphicsWindow.Height = h
GraphicsWindow.CanResize = 1
GraphicsWindow.BackgroundColor = "black"
'
' set up the player's start position and direction
' these are the x/y co-ordinates of the world map
' nb absolute values place the player at grid intersections!!
posX = 5.5
posY = 10.5
dirX = 1
dirY = 0
planeX = 0
'
' plane y is the size of the viewing plane in degrees
' (altering this gives different perspective views)
planeY = 0.66
completed = 1
'
' movespeed is how far forward you move each step.
' bigger values create bigger steps, lower values mean smaller (smoother) steps
' rotspeed is how much you rotate left/right when you turn
' a value of 1/3 of rotspeed seems about right
moveSpeed = 0.2
rotSpeed = 0.07
' set up the key press interrupts
GraphicsWindow.Keydown = OnKeydown
GraphicsWindow.Keyup = OnKeyup
' call the setupmap subroutine to draw the initial map view
setupmap()
main()
Loop:
Goto loop
Sub onkeydown
If completed = 1 Then 'ensures that will not try to draw, when previous frame is still drawing
keypress = GraphicsWindow.LastKey
moveX = dirX * movespeed
moveY = dirY * movespeed
' checks that nothing is in front then moves forward
If keypress = "Up" Then
If worldMap[Math.Floor(posX + moveX)][Math.Floor(posy)] = 0 Then
posX = posX + moveX
Endif
If worldMap[Math.Floor(posx)][math.Floor(posY + moveY)] = 0 Then
posY = posY + moveY
Endif
Endif
' checks that nothing is in behind then moves backwards
If keypress = "Down" Then
If worldMap[Math.Floor(posX - dirX * moveX)][Math.Floor(posy)] = 0 Then
posX = posX - moveX
Endif
If worldMap[Math.Floor(posx)][math.Floor(posY - moveY)] = 0 Then
posY = posY - moveY
Endif
Endif
' rotate the view anticlockwise if turning left
If keypress = "Left" Then
oldDirx = dirX
CosrotspeedL = Math.Cos(-1 * rotspeed)
SinrotspeedL = Math.Sin(-1 * rotspeed)
dirX = dirX * CosrotspeedL - dirY * SinrotspeedL
dirY = oldDirX * SinrotspeedL + dirY * CosrotspeedL
oldPlanex = planeX
planeX = planeX * CosrotspeedL - planeY * SinrotspeedL
planeY = oldPlaneX * SinrotspeedL + planeY * CosrotspeedL
'
'
EndIf
' rotate the view clockwise if turning right
If keypress = "Right" Then
oldDirx = dirX
CosrotspeedR = Math.Cos(rotspeed)
SinrotspeedR = Math.Sin(rotspeed)
dirX = dirX * CosrotspeedR - dirY * SinrotspeedR
dirY = oldDirX * SinrotspeedR + dirY * CosrotspeedR
oldPlaneX = planeX
planeX = planeX * CosrotspeedR - planeY * SinrotspeedR
planeY = oldPlaneX * SinrotspeedR + planeY * CosrotspeedR
'
'
EndIf
'call main subroutine to draw the new frame/view
main()
EndIf
EndSub
Sub OnKeyUp
keypress = ""
EndSub
sub main
completed = 0
For x = 0 To w / size ' calculate ray position and direction
cameraX = 2 * x / (w / size) - 1 ' x-coordinate in camera space
rayPosX = posX
rayPosY = posY
rayDirX = dirX + planeX * cameraX
rayDirY = dirY + planeY * cameraX
'
'which box of the map we're in
mapX = Math.Floor(rayPosX)
mapY = Math.Floor(rayPosY)
' length of ray from current position to next x or y-side
sideDistX = 0
sideDistY = 0
' length of ray from one x or y-side to next x or y-side
deltaDistX = Math.SquareRoot(1 + (rayDirY * rayDirY) / (rayDirX * rayDirX))
deltaDistY = Math.SquareRoot(1 + (rayDirX * rayDirX) / (rayDirY * rayDirY))
perpWallDist = 0
'what direction to step in x or y-direction (either +1 or -1)
stepX = 0
stepY = 0
hit = 0 ' was there a wall hit?
side = 0 ' was a NS or a EW wall hit?
' perform DDA
' trace a "ray" until it hits a wall, and determine if it's an "X" (horizontal) or "Y" (vertical) wall
While hit = 0 ' jump to next map square, OR in x-direction, OR in y-direction
If sideDistX < sideDistY Then
sideDistX = sideDistX + deltaDistX
mapX = mapx + stepX
side = 0
Else
sideDistY = sideDistY + deltaDistY
mapY = mapy + stepY
side = 1
EndIf
' Check if ray has hit a wall
If worldMap[mapX][mapY] > 0 Then
hit = 1
EndIf
EndWhile
' Calculate distance projected on camera direction.
If side = 0 Then
perpWallDist = Math.Abs((mapX - rayPosX + (1 - stepX) / 2) / rayDirX)
Else
perpWallDist = Math.Abs((mapY - rayPosY + (1 - stepY) / 2) / rayDirY)
EndIf
' Calculate height of line to draw on screen
lineHeight = Math.Abs(h / perpWallDist)
lineHeight = Math.Round (lineheight)
'if height if line to be drawn is > than height of graphics window then limit height of line
If lineHeight > h Then
lineHeight = h
EndIf
'
' calculate lowest and highest pixel to fill in current stripe
drawStart = (lineHeight * -1) / 2 + h / 2
If drawStart < 0 Then
drawStart = 0
EndIf
drawEnd = lineHeight / 2 + h / 2
If drawEnd >= h Then
drawEnd = h - 1
EndIf
' set up the colours depending on the block numbers
' default colour is grey (RGB values are equal)
' red
If worldMap[mapx][mapy] = 2 Then
coldistr = coladj
coldistg = 0
coldistb = 0
EndIf
'green
If worldMap[mapx][mapy] = 3 Then
coldistr = 0
coldistg = coladj
coldistb = 0
EndIf
'blue
If worldMap[mapx][mapy] = 4 Then
coldistr = 0
coldistg = 0
coldistb = coladj
EndIf
'magenta
If worldMap[mapx][mapy] = 5 Then
coldistr = coladj
coldistg = 0
coldistb = coladj
EndIf
'yellow
If worldMap[mapx][mapy] = 6 Then
coldistr = coladj
coldistg = coladj
coldistb = 0
EndIf
colour = GraphicsWindow.GetColorFromRGB(coldistr, coldistg, coldistb)
If side = 1 Then
colour = GraphicsWindow.GetColorFromRGB(coldistr / 1.3, coldistg / 1.3, coldistb / 1.3)
EndIf
'draw the pixels of the stripe as a vertical line
GraphicsWindow.PenWidth = size
GraphicsWindow.PenColor = colour
'
' if the colour intensity is > 0 then draw the line,
GraphicsWindow.DrawLine (x * size,drawStart,x * size,drawEnd)
GraphicsWindow.PenColor = "black"
GraphicsWindow.DrawLine (x * size,0,x*size,drawstart)
GraphicsWindow.PenColor = "black"
GraphicsWindow.DrawLine (x * size,drawend,x*size,h)
'
' define some parameters that state how big the map is
mapsizex = Text.GetLength (mapline[1])
mapsizey = array.GetItemCount (mapline)
'
'try to read this in and convert it into a two dimensional array
For yloop = 1 To mapsizey
For xloop = 1 To mapsizex
worldmap[xloop][yloop] = Text.GetSubText(mapline[yloop],xloop,1)
EndFor
EndFor
EndSub
Program Listing: RVR504