Thanks very much, I've actually come up with a different method, using a circle instead of just a point for the player. Basically I check the distance from the center of the circle to each line segment, and if that distance is less than the circle's radius then it's colliding. If it's colliding then I change the velocity vector of the circle to be parallel with the line, then I multiply the velocity vector by the cosine of the difference between the angle of the line and the angle of the player, and this slows down the player depending on how directly he's facing the wall.
Once again I'm pretty bad at explaining so I'll post my new code and you can take a look at it.
SuperStrict
Type TPoint
Field X:Float
Field Y:Float
Function Create:TPoint(X:Float, Y:Float)
Local Point:TPoint = New TPoint
Point.X = X
Point.Y = Y
Return Point
EndFunction
EndType
Type TLine
Field P1:TPoint
Field P2:TPoint
Method New()
P1 = New TPoint
P2 = New TPoint
EndMethod
Function Create:TLine(X1:Float, Y1:Float, X2:Float, Y2:Float)
Local Line:TLine = New TLine
Line.P1.X = X1
Line.P1.Y = Y1
Line.P2.X = X2
Line.P2.Y = Y2
Return Line
EndFunction
EndType
Graphics(1024, 768, 1)
Global g_ColPoint:TPoint = New TPoint
Global g_IntersectPoint:TPoint = New TPoint
Local LineList:TList = CreateList()
LineList.AddLast(TLine.Create(100, 100, 500, 100))
LineList.AddLast(TLine.Create(500, 100, 500, 500))
LineList.AddLast(TLine.Create(250, 100, 250, 500))
Local PlayerPos:TPoint = New TPoint
PlayerPos.X = 350
PlayerPos.Y = 250
Local PlayerVel:TPoint = New TPoint
Local PlayerOldPos:TPoint = New TPoint
Local PlayerRadius:Float = 8.0
Local PlayerAng:Float = 0.0
Local ColPoint:TPoint = New TPoint
Repeat
Cls
DrawText("Control the circle with the arrowkeys - UP = Move forward - DOWN = Move backward - RIGHT = Turn right - LEFT = Turn left", 10, 10)
PlayerOldPos.X = PlayerPos.X
PlayerOldPos.Y = PlayerPos.Y
PlayerVel.X = 0.0
PlayerVel.Y = 0.0
If KeyDown(KEY_UP)
PlayerVel.X = Sin(PlayerAng) * 4.0
PlayerVel.Y = Cos(PlayerAng) * 4.0
EndIf
If KeyDown(KEY_LEFT)
PlayerAng = PlayerAng + 4.0
EndIf
If KeyDown(KEY_RIGHT)
PlayerAng = PlayerAng - 4.0
EndIf
If KeyDown(KEY_DOWN)
PlayerVel.X = -Sin(PlayerAng) * 4.0
PlayerVel.Y = -Cos(PlayerAng) * 4.0
EndIf
For Local L:TLine = EachIn LineList
If DistanceToLineSegment(L.P1.X, L.P1.Y, L.P2.X, L.P2.Y, PlayerPos.X + PlayerVel.X, PlayerPos.Y + PlayerVel.Y) <= PlayerRadius
Local LineAng:Float
Local PlayerAng:Float
Local AngDif:Float
LineAng = ATan((L.P2.Y - L.P1.Y) / (L.P2.X - L.P1.X))
PlayerAng = ATan(PlayerVel.Y / PlayerVel.X)
AngDif = PlayerAng - LineAng
If PlayerVel.X > 0.0
PlayerVel.X = Cos(LineAng) * 4.0 * Cos(AngDif)
PlayerVel.Y = Sin(LineAng) * 4.0 * Cos(AngDif)
Else
PlayerVel.X = Cos(LineAng) * 4.0 * -Cos(AngDif)
PlayerVel.Y = Sin(LineAng) * 4.0 * -Cos(AngDif)
EndIf
EndIf
Next
PlayerPos.X = PlayerPos.X + PlayerVel.X
PlayerPos.Y = PlayerPos.Y + PlayerVel.Y
DrawCircle(PlayerPos.X, PlayerPos.Y, PlayerRadius)
DrawLineList(LineList)
Flip
Until KeyHit(KEY_ESCAPE)
Function DrawLineList(List:TList)
For Local L:TLine = EachIn List
DrawLine(L.P1.X, L.P1.Y, L.P2.X, L.P2.Y)
Next
EndFunction
Function DistanceToLineSegment:Double(ax:Double,ay:Double, bx:Double,by:Double, px:Double,py:Double)
'Returns the distance from p to
' the closest point on line segment a-b.
Local dx:Double=bx-ax
Local dy:Double=by-ay
Local t:Double = ( (py-ay)*dy + (px-ax)*dx ) / (dy*dy + dx*dx)
If t<0
dx=ax
dy=ay
ElseIf t>1
dx=bx
dy=by
Else
dx = ax+t*dx
dy = ay+t*dy
End If
dx:-px
dy:-py
g_ColPoint.X = PX + DX
g_ColPoint.Y = PY + DY
Return Sqr(dx*dx + dy*dy)
End Function
Function DistanceToLine:Double(ax:Double,ay:Double, bx:Double,by:Double, px:Double,py:Double)
'Returns the distance from p to the closest point
' ont the line passing through a and b.
Local dx:Double=bx-ax
Local dy:Double=by-ay
Return ( (ay-py)*dx + (px-ax)*dy ) / Sqr(dy*dy + dx*dx)
EndFunction
Function LineIntersection(line11x:Float, line11y:Float, line12x:Float, line12y:Float, line21x:Float, line21y:Float, line22x:Float, line22y:Float)
'Calculate intersection point.
g_IntersectPoint.X = line11x + (((line22x-line21x)*(line11y-line21y)-(line22y-line21y)*(line11x-line21x))/((line22y-line21y)*(line12x-line11x)-(line22x-line21x)*(line12y-line11y)))*(line12x-line11x)
g_IntersectPoint.Y = line11y + (((line22x-line21x)*(line11y-line21y)-(line22y-line21y)*(line11x-line21x))/((line22y-line21y)*(line12x-line11x)-(line22x-line21x)*(line12y-line11y)))*(line12y-line11y)
EndFunction
Function CCW:Int(P1:TPoint, P2:TPoint, P3:TPoint)
Local DX1:Int
Local DX2:Int
Local DY1:Int
Local DY2:Int
DX1 = P2.x - P1.x
DY1 = P2.y - P1.y
DX1 = P3.x - P1.x
DY2 = P3.y - P1.y;
If dx1*dy2 > dy1*dx2
Return 1
EndIf
If dx1*dy2 < dy1*dx2
Return -1
EndIf
If (dx1*dx2 < 0) Or (dy1*dy2 < 0)
Return -1
EndIf
If (dx1*dx1 + dy1*dy1) < (dx2*dx2 + dy2*dy2)
Return 1
EndIf
Return 0
EndFunction
Function DrawCircle(xCentre:Float, yCentre:Float, Radius:Float)
DrawOval(xCentre - (Radius), yCentre - (Radius), Radius * 2, Radius * 2)
EndFunction
There are still quite a few problems with it--the circle occasionally gets stuck on outside corners, and sometimes it will just randomly disappear--so if you have a better method (and you probably do) then I'd appreciate it if you could do the write-up on your blog, although I'm still going to attempt to improve this one as well.
Thanks!
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