Ray Casting

BlitzMax Forums/BlitzMax Programming/Ray Casting

MattVonFat (Posted 2005) [#1]

I've been trying for a week now to get some simple ray casting working. I have made 3 different versions (issues with me not saving properly :P) and only two of them had any sort of workability. When I started I just did horizontal checks and I could get a strait wall but when I started to use verticle checks aswell I started to get problems. There should be any problems with the verticle checks as it is a copy of the horizontal version with the bits that need to be changed changed. Here's what I have so far. Its part of a corner and even though there should be some walls that were from verticle checks there isnt (they should be in red - horizontal in blue). The littl map at the bottom shows which direction the person is pointing. Rem RAY CASTING The ray casting test program. will hopefully work! End Rem SuperStrict Type Point Field X:Int Field Y:Int Field GX:Int Field GY:Int Field XA:Int Field YA:Int Field Distance:Int Field Exist:Int=True End Type Global H:Point 'Horizontal checks Global V:Point 'Verticle checks Global Width:Int=4, Height:Int=4 Global Grid:Int[Width,Height] SetUpGrid() Global PlayerX:Int = 256 Global PlayerY:Int = 256 Global PlayerR:Float = 135 Global CurrentRayAngle:Float, Count1:Int, CDistance:Float, CosB:Float, Proj:Float, Direction:String Graphics 800, 600, 32 Trace() While Not KeyHit(KEY_ESCAPE) If KeyHit(KEY_LEFT) Then PlayerR:+1; Trace() If KeyHit(KEY_RIGHT) Then PlayerR:-1; Trace() Wend Function Trace() CurrentRayAngle = PlayerR+30.0 Cls For Count1 = 0 To 319 'Go through columns H = New Point V = New Point TraceH() TraceV() If V.Exist = False And H.Exist = False Else If V.Exist = True And H.Exist = True If V.Exist < H.Exist Then CDistance = V.Distance; Direction ="V" If H.Exist < V.Exist Then CDistance = H.Distance; Direction = "H" Else If V.Exist = True Then CDistance = V.Distance; Direction = "V" If H.Exist = True Then CDistance = H.Distance; Direction = "H" End If CosB = (30.0)-((60.0/320.0)*Float(Count1)) 'Sort out distance problems - H.Distance:*Cos(CosB) '- find correct distance Proj = 64.0/H.Distance*277.0 'work out slice height DrawSlice(Proj,Direction) End If CurrentRayAngle:-(60.0/320.0) H=Null V=Null Next DrawMap() Flip End Function Function TraceH() If PlayerR < 180 And PlayerR > 0 Then H.Y = Floor(PlayerY/64)*64-1 If PlayerR > 180 And PlayerR < 0 Then H.Y = Floor(PlayerY/64)*64+64 H.GY = H.Y/64 H.X = PlayerX+(PlayerY-H.Y)/Tan(CurrentRayAngle) H.GX = H.X/64 If H.GX > -1 And H.GX < Width And H.GY > -1 And H.GY < Height If Grid[H.GX,H.GY] = 1 'We hit an object! H.Distance = Sqr(((PlayerX-H.X)*(PlayerX-H.X))+((PlayerY-H.Y)*(PlayerY-H.Y))) Else 'Better keep looking! Repeat 'We may need to go through this alot If PlayerR < 180 And PlayerR > 0 Then H.YA = -64 If PlayerR > 180 And PlayerR < 0 Then H.YA = 64 H.Y:+H.YA H.GY = H.Y/64 H.XA = 64/Tan(CurrentRayAngle) H.X:+H.XA H.GX=H.X/64 If H.GX > -1 And H.GX < Width And H.GY > -1 And H.GY < Height If Grid[H.GX,H.GY] = 1 'We hit an object! H.Distance = Sqr(((PlayerX-H.X)*(PlayerX-H.X))+((PlayerY-H.Y)*(PlayerY-H.Y))) Exit End If Else H.Exist = False Exit End If Forever End If Else H.Exist = False 'There is nothing in this line of sight (shouldnt happen with default map) End If End Function Function TraceV() If PlayerR > 90 And PlayerR < 270 V.X = Floor(PlayerX/64)*64-1 Else V.X = Floor(PlayerX/64)*64+64 End If V.GX = V.X/64 V.Y = PlayerY+(PlayerX-V.X)*Tan(CurrentRayAngle) V.GY = V.Y/64 If V.GX > -1 And V.GX < Width And V.GY > -1 And V.GY < Height If Grid[V.GX,V.GY] = 1 'We hit an object! V.Distance = Sqr(((PlayerX-V.X)*(PlayerX-V.X))+((PlayerY-V.Y)*(PlayerY-V.Y))) Else 'Better keep looking! Repeat 'We may need to go through this alot If PlayerR > 90 And PlayerR < 270 V.XA = -64 Else V.XA = 64 End If V.X:+V.XA V.GX = V.X/64 V.YA = 64*Tan(CurrentRayAngle) V.Y:+V.YA V.GY=V.Y/64 If V.GX > -1 And V.GX < Width And V.GY > -1 And V.GY < Height If Grid[V.GX,V.GY] = 1 'We hit an object! V.Distance = Sqr(((PlayerX-V.X)*(PlayerX-V.X))+((PlayerY-V.Y)*(PlayerY-V.Y))) Exit End If Else V.Exist = False Exit End If Forever End If Else V.Exist = False 'There is nothing in this line of sight (shouldnt happen with default map) End If End Function Function DrawSlice(Height:Int,Dir:String) If Dir = "H" Then SetColor 0, 0, 255 If Dir = "V" Then SetColor 255, 0, 0 DrawLine(Count1,100-(Height/2),Count1,100+(Height/2)) End Function Function DrawMap() Local CountA:Int,CountB:Int SetColor 0, 255, 0 DrawLine 320, 0, 320, 200 DrawLine 0, 200, 320, 200 DrawText "PlayerX: " + PlayerX, 330, 10 DrawText "PlayerY: " + PlayerY, 330, 30 DrawText "PlayerR: " + PlayerR, 330, 50 For CountA = 3 To 0 Step -1 For CountB = 3 To 0 Step -1 If Grid[CountA,CountB] = 1 SetColor 255, 0, 0 If Grid[CountA,CountB] = 0 SetColor 255, 255, 255 DrawHollowRect(100+(64*CountA),300+(64*CountB),64,64) Next Next SetColor 0, 0, 255 Plot PlayerX+100, PlayerY+300 SetColor 0, 255, 0 DrawLine PlayerX+100, PlayerY+300, PlayerX+(300*Sin(PlayerR-270)+100), PlayerY+(300*Cos(PlayerR-270)+300) DrawLine PlayerX+100, PlayerY+300, PlayerX+(300*Sin((PlayerR-30)-270)+100), PlayerY+(300*Cos((PlayerR-30)-270)+300) DrawLine PlayerX+100, PlayerY+300, PlayerX+(300*Sin((PlayerR+30)-270)+100), PlayerY+(300*Cos((PlayerR+30)-270)+300) End Function Function DrawHollowRect(x:Int, y:Int, w:Int, h:Int) DrawLine x, y, x+w, y DrawLine x, y, x, y+h DrawLine x+w, y, x+w, y+h DrawLine x, y+h, x+w, y+h End Function Function SetUpGrid() Grid[0,0] = 1 Grid[1,0] = 1 Grid[2,0] = 1 Grid[3,0] = 1 Grid[0,1] = 1 'Grid[0,2] = 1 'Grid[0,3] = 1 End Function I'm sure that the problem is simple to work out, and I would have liked to have been able to work it out myself, but I just can't get it. I've gone through the permadi tutorial over and over and have been checking each equation to make sure that I didn't didnt divide when I should have multiplied and other little errors like that, but I'm sure I've sorted all those little things out now. Any help that can be given on this problem is highly appreciated. Thanks Matthew

GW (Posted 2005) [#2]

Did you check the raycasting demo that comes with Bmax?

MattVonFat (Posted 2005) [#3]

I thought I'd seen a demo with BlitzMAX but when I looked for it I couldn't find it. I had a look through them again just now but it doesnt seem to be there.