; getAngle.pbi


Procedure.f getAngle(mx,my, px,py, mode.l=1)
; returns the angle of a line going from point
; [mx,my] to point [px,py] in radian
; mode=1 (default):
; pointing to the right means 0 degrees
; pointing to the top means 90 degrees, ect
; [math y-axis]
; mode=-1:
; pointing to the right means 0 degrees
; pointing to the bottom means 90 degrees, ect
; [screen y-axis.]

  Static xd.l, yd.l, alpha.f
  xd=px-mx
  yd=py-my
  
  If xd>0
    If     yd<0 :: alpha=         ATan(-yd / xd )
    ElseIf yd>=0 :: alpha= 2*#PI - ATan( yd / xd )
    EndIf
  ElseIf xd<0
    If     yd<0 :: alpha=   #PI - ATan(-yd /-xd )
    ElseIf yd>=0 :: alpha=   #PI + ATan( yd /-xd )
    EndIf
  ElseIf xd=0
    If     yd>0 : alpha=   #PI*1.5
    ElseIf yd<0 : alpha=   #PI*0.5
    EndIf
  EndIf
  If mode=-1
    alpha = 2*#PI-alpha
  EndIf
;   If Not Random(200)
;     Debug Str(xd) + " | " + Str(yd) + " | " + StrF(alpha)
;   EndIf
  ProcedureReturn alpha
EndProcedure


; [merge_end]







; Debug "---- EXAMPLE - getAngle.pbi"
; Debug getAngle(400,400, 450,350)    *180/#PI
; Debug getAngle(400,400, 350,350)    *180/#PI
; Debug getAngle(400,400, 350,450)    *180/#PI
; Debug getAngle(400,400, 450,450)    *180/#PI
; Debug ""
; Debug getAngle(0,0, -50,-1)*180/#PI
; Debug getAngle(0,0, -50,0)*180/#PI
; Debug getAngle(0,0, -50,1)*180/#PI
; Debug ""
; Debug getAngle(100,100, 50,99)*180/#PI
; Debug getAngle(100,100, 50,100)*180/#PI
; Debug getAngle(100,100, 50,101)*180/#PI
; Debug "----"
; OpenWindow(0,100,100,400,400,"")
; Repeat
; StartDrawing(WindowOutput(0)) :: Box(0,0,400,400,$333333)
;   Circle(200,200,2,$ff00)::Circle(WindowMouseX(0),WindowMouseY(0),2,$ff00)
;   a.f = getAngle(200,200,WindowMouseX(0),WindowMouseY(0))
;   LineXY(200,200,WindowMouseX(0),WindowMouseY(0),$ff0000) :: DrawText(10,10,Str(a*180/#PI)+"°")
; StopDrawing()
; Until WaitWindowEvent(100) = #PB_Event_CloseWindow






; IDE Options = PureBasic 4.20 Beta 2 (Windows - x86)
; CursorPosition = 16
; Folding = -
; CompileSourceDirectory