Fixed the problem with the line end points with another method using vectors:
Strict Graphics 800,600,0 Global c:TCircle = TCircle.Create(0,0,50) c.color = TColor.Create(255,255,255) Global l:TLine = TLine.Create(100,100,400,400) l.CalcLength() While Not KeyHit(key_escape) 'Place cicle where mouse is c.x = MouseX() c.y = MouseY() 'Change colour depending on collision status If ccCircleLineIntersect2(c,l) Then c.color.set(255,0,0) Else c.color.set(0,255,0) EndIf 'Draw the scene Cls c.Draw() l.draw() Flip Wend '---------------------------------------------------- Type TCircle Field x# Field y# Field r# 'radius Field Color:TColor Function Create:TCircle(x,y,r) c:TCircle = New TCircle c.x=x c.y=y c.r=r Return c End Function Method Draw() If Color<>Null Then Color.Apply DrawOval(x-r,y-r,r*2,r*2) If Color<>Null Then Color.Restore End Method End Type Type TLine Field sx# Field sy# Field ex# Field ey# Field length# Field Color:TColor Function Create:TLine(sx,sy,ex,ey) l:TLine = New TLine l.sx=sx l.sy=sy l.ex=ex l.ey=ey Return l End Function Method CalcLength#() length = Sqr((ex-sx)*(ex-sx)+(ey-sy)*(ey-sy)) End Method Method Draw(DrawLastPixel=True) If Color<>Null Then Color.Apply DrawLine(sx,sy,ex,ey,DrawLastPixel) If Color<>Null Then Color.Restore End Method End Type Type TColor 'I'm using American spelling to keep it more like the Blitz commands. Field R=0 Field G=0 Field B=0 Field Alpha#=1 Function Create:TColor(r,g,b,alpha#=1) Local c:TColor = New TColor c.Set(r,g,b,alpha) Return c End Function Method Set(tR,tG,tB,talpha#=1) R = tR G = tG B = tB Alpha = tAlpha End Method Method Get(tR Var,tG Var,tB Var) tR = R tG = G tB = B End Method Method GetFull(tR Var,tG Var,tB Var, tAlpha# Var) tR = R tG = G tB = B tAlpha = Alpha End Method Method Apply() SetColor R,G,B SetAlpha Alpha End Method Method ApplyNoAlpha() SetColor R,G,B End Method Method Copy(c:TColor) R=c.R G=c.G B=c.B Alpha=c.Alpha End Method Method Restore() SetColor 255,255,255 SetAlpha 1 End Method End Type Type TVector Field x# Field y# Function Create:TVector(x,y) Local v:TVector = New TVector v.x=x v.y=y Return v End Function Method AddVector(v:TVector) x:+v.x y:+v.y End Method Method CopyFrom(source:TVector) x=source.x y=source.y End Method Method DotProduct#(v2:TVector) Return x*v2.x + y*v2.y End Method Method Multiply(multiplier#) x:*multiplier y:*multiplier End Method Method SubtractVector(v:TVector) x:-v.x y:-v.y End Method End Type Function ccCircleLineIntersect%(c:TCircle,l:TLine) 'Make sure you precalc the line length Local x0# = c.x Local y0# = c.y Local x1# = l.sx Local y1# = l.sy Local x2# = l.ex Local y2# = l.ey Local n# = Abs((x2-x1)*(y1-y0)-(x1-x0)*(y2-y1)) Local d# = l.length Local dist# = n/d If dist > c.r Return False Local d1# = Sqr((x0-x1)*(x0-x1)+(y0-y1)*(y0-y1)) If d1-c.r > d Return False Local d2# = Sqr((x0-x2)*(x0-x2)+(y0-y2)*(y0-y2)) If d2-c.r > d Return False Return True End Function Function ccCircleLineIntersect2%(c:TCircle,l:TLine) Local cv:TVector = TVector.Create(c.x,c.y) Local p1:TVector = TVector.Create(l.sx,l.sy) Local p2:TVector = TVector.Create(l.ex,l.ey) Local dir:TVector = ccVectorSubtract(p2,p1) Local diff:TVector = ccVectorSubtract(cv,p1) Local t# = diff.DotProduct(dir) / dir.DotProduct(dir) If t < 0 Then t = 0 If t > 1 Then t = 1 Local closest:TVector = ccVectorAdd(p1, ccVectorMultiply(dir,t)) Local d:TVector = ccVectorSubtract(cv,closest) Local distsqr# = d.DotProduct(d) Return distsqr <= c.r * c.r End Function Function ccVectorAdd:TVector(v1:TVector,v2:TVector) Local result:TVector = New TVector result.CopyFrom(v1) result.AddVector(v2) Return result End Function Function ccVectorSubtract:TVector(v1:TVector,v2:TVector) Local result:TVector = New TVector result.CopyFrom(v1) result.SubtractVector(v2) Return result End Function Function ccVectorMultiply:TVector(v:TVector,multiplier#) Local result:TVector = New TVector result.CopyFrom(v) result.Multiply(multiplier) Return result End Function