Microsoft Small Basic

Program Listing: BRS931

List Program

Main:
w = 1023 ' screen width
h = 768 'screen height
size = 10
'w = 512 ' screen width
'h = 384 'screen height
GraphicsWindow.Width = w
GraphicsWindow.Height = h
GraphicsWindow.CanResize = 1
GraphicsWindow.BackgroundColor = "black"
posX = 5.5
posY = 10.5 ' x and y start positions
dirX = 1
dirY = 0 ' initial direction vector
planeX = 0
' planeY = 0.66 ' the 2d raycaster version of camera plane
planeY = 0.66 ' the 2d raycaster version of camera plane
time = 0 ' time of current frame
oldTime = 0 ' time of previous frame
completed = 1
moveSpeed = 0.4
rotSpeed = 0.1
'moveSpeed = 0.2
'rotSpeed = 0.07

GraphicsWindow.Keydown = OnKeydown
GraphicsWindow.Keyup = OnKeyup

setupmap()
main()
Loop:
Goto loop

Sub onkeydown
If completed = 1 Then
keypress = GraphicsWindow.LastKey

'move forward if nothing is in front
If keypress = "Up" Then
If worldMap[Math.Floor(posX + dirX * moveSpeed)][Math.Floor(posy)] = 0 Then
posX = posX + dirX * moveSpeed
Endif
If worldMap[Math.Floor(posx)][math.Floor(posY + dirY * movespeed)] = 0 Then
posY = posY + dirY * movespeed
Endif
Endif

' move backwards if nothing is behind
If keypress = "Down" Then
If worldMap[Math.Floor(posX - dirX * moveSpeed)][Math.Floor(posy)] = 0 Then
posX = posX - dirX * moveSpeed
Endif
If worldMap[Math.Floor(posx)][math.Floor(posY - dirY * movespeed)] = 0 Then
posY = posY - dirY * movespeed
Endif
Endif

If keypress = "Left" Then
oldDirx = dirX
dirX = dirX * Math.cos(-1 * rotSpeed) - dirY * Math.sin(-1 * rotSpeed)
dirY = oldDirX * Math.sin(-1 * rotSpeed) + dirY * Math.cos(-1 * rotSpeed)
oldPlanex = planeX
planeX = planeX * Math.cos(-1 * rotSpeed) - planeY * Math.sin(-1 * rotSpeed)
planeY = oldPlaneX * Math.sin(-1 * rotSpeed) + planeY * Math.cos(-1 * rotSpeed)
'
'
EndIf

If keypress = "Right" Then
oldDirx = dirX
dirX = dirX * Math.cos(rotSpeed) - dirY * Math.sin(rotSpeed)
dirY = oldDirX * Math.sin(rotSpeed) + dirY * Math.cos(rotSpeed)
oldPlaneX = planeX
planeX = planeX * Math.cos(rotSpeed) - planeY * Math.sin(rotSpeed)
planeY = oldPlaneX * Math.sin(rotSpeed) + planeY * Math.cos(rotSpeed)
'
'
EndIf
main()
EndIf
EndSub

Sub OnKeyUp
keypress = ""
EndSub


sub main
completed = 0
'For x = 0 To w / 2 ' calculate ray position and direction
' cameraX = 2 * x / w - 1 ' x-coordinate in camera space
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?

' calculate step and initial sideDist
If rayDirX < 0 Then
stepX = -1
sideDistX = (rayPosX - mapX) * deltaDistX
Else
stepX = 1
sideDistX = (mapX + 1.0 - rayPosX) * deltaDistX
EndIf
If rayDirY < 0 then
stepY = -1
sideDistY = (rayPosY - mapY) * deltaDistY
Else
stepY = 1
sideDistY = (mapY + 1.0 - rayPosY) * deltaDistY
EndIf


' perform DDA
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 (oblique distance will give fisheye effect!)
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 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
coldistr = math.SquareRoot(lineHeight*50)
coldistg = math.SquareRoot(lineHeight*50)
coldistb = math.SquareRoot(lineHeight*50)

' red
If worldMap[mapx][mapy] = 2 Then
coldistr = math.SquareRoot(lineHeight*50)
coldistg = 2
coldistb = 2
EndIf
'green
If worldMap[mapx][mapy] = 3 Then
coldistr = 2
coldistg = math.SquareRoot(lineHeight*50)
coldistb = 2
EndIf
'blue
If worldMap[mapx][mapy] = 4 Then
coldistr = 2
coldistg = 2
coldistb = math.SquareRoot(lineHeight*50)
EndIf
'magenta
If worldMap[mapx][mapy] = 5 Then
coldistr = math.SquareRoot(lineHeight*50)
coldistg = 2
coldistb = math.SquareRoot(lineHeight*50)
EndIf
'yellow
If worldMap[mapx][mapy] = 6 Then
coldistr = math.SquareRoot(lineHeight*50)
coldistg = math.SquareRoot(lineHeight*50)
coldistb = 2
EndIf



If coldistr > 200 Then
coldistr = 200
EndIf
If coldistg > 200 Then
coldistg = 200
EndIf
If coldistb > 200 Then
coldistb = 200
EndIf
colour = GraphicsWindow.GetColorFromRGB(coldistr, coldistg, coldistb)
'colour = "#202020"
If side = 1 Then
colour = GraphicsWindow.GetColorFromRGB(coldistr / 2, coldistg / 2, coldistb / 2)
'colour = "#505050"
EndIf


'//draw the pixels of the stripe as a vertical line
GraphicsWindow.PenWidth = size
GraphicsWindow.PenColor = colour
'GraphicsWindow.DrawLine (x,drawStart,x,drawEnd)
GraphicsWindow.DrawLine (x * size,drawStart,x * size,drawEnd)
GraphicsWindow.PenColor = "blue"
GraphicsWindow.DrawLine (x * size,0,x*size,drawstart-1)
GraphicsWindow.PenColor = "black"
GraphicsWindow.DrawLine (x * size,drawend+1,x*size,h)

EndFor
completed = 1
Endsub







Sub setupmap
mapwidth = 21
mapheight = 21
'define the map in the mapline array as strings
mapline[1] = "155555511111111555555"
mapline[2] = "600000000000000000005"
mapline[3] = "600000002000005000051"
mapline[4] = "600000000000305000051"
mapline[5] = "600000002600305022201"
mapline[6] = "604020006000005000001"
mapline[7] = "604031006016604444441"
mapline[8] = "600000000010004000001"
mapline[9] = "600230000010004000001"
mapline[10] = "100000000000004000003"
mapline[11] = "100002200022000000003"
mapline[12] = "100000000000000000033"
mapline[13] = "100002200022000333033"
mapline[14] = "100000000000000033031"
mapline[15] = "103333311111111011011"
mapline[16] = "100000011110000000002"
mapline[17] = "100000001110000000002"
mapline[18] = "100200000110000000002"
mapline[19] = "100000000116543211302"
mapline[20] = "100000000000000000003"
mapline[21] = "111111111116543211222"

'
' 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