Rotator 1.1

Added on 6/10/1999

Compatibilities:
behavior D6_5 Mac

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Note that you can easily add more motion options... the exitFrame handler dispatches the event to the chosen method.

property spriteNum
property myStartArt, numberOfGraphics
property rotateType, spriteTarget, rotationDuration
property oldLoc, rotateAngle, startTime

--======  EXTERNAL EVENTS:

on beginSprite me
  GetArtwork me
  set oldLoc to the loc of sprite spriteNum
  set rotateAngle to 360.0/numberOfGraphics
  set startTime to the ticks
  set rotationDuration to rotationDuration * 60.0/ numberOfGraphics
end

on exitFrame me
  case (rotateType) of
    "Align with sprite's motion": RotateWithMotion me
    "Point to mouse": PointToMouse me
    "Point at another sprite": PointAtSprite me
    "Time based": IncrementTimer me
  end case
end

--======  VARIOUS OPTIONS FOR MOTION:

on RotateWithMotion me
  set newLoc to the loc of sprite spriteNum
  set delta to newLoc - oldLoc
  if abs(the locH of delta) < 1 AND abs(the locV of delta) < 1 then exit
  set theAngle to GetAngle(newLoc - oldLoc)
  set offset to integer(theAngle/rotateAngle) mod numberOfGraphics
  set the member of sprite spriteNum to myStartArt + offset
  set oldLoc to newLoc
end

on PointToMouse me
  set theAngle to GetAngle(point(the mouseH, the mouseV) - the loc of sprite spriteNum)
  set offset to integer(theAngle/rotateAngle) mod numberOfGraphics
  set the member of sprite spriteNum to myStartArt + offset
end

on PointAtSprite me
  set myLoc to the loc of sprite spriteNum
  set targetLoc to the loc of sprite spriteTarget
  set theAngle to GetAngle(targetLoc - myLoc)
  set offset to integer(theAngle/rotateAngle) mod numberOfGraphics
  set the member of sprite spriteNum to myStartArt + offset
end

on IncrementTimer me
  set now to (the ticks - startTime) / rotationDuration
  set offset to integer(now) mod numberOfGraphics
  set the member of sprite spriteNum to myStartArt + offset
end

--======  UTILITY ROUTINES:

--  Takes x,y position, converts to 0-360 angle.
--  Origin is at top and direction is clockwise.
on GetAngle thePoint
  set x to the locH of thePoint
  set y to the locV of thePoint

  if y = 0 then set y = 0.0001

  set angle to atan(float(x) / y) * -180/pi()

  if y >= 0 and x >= 0 then
    set angle = 180 + angle
  else if x < 0 and y >= 0 then
    set angle = 180 + angle
  else if y < 0 and x < 0 then
    set angle = 360 + angle
  else
    nothing
  end if

  return angle

end

--  Counts how many graphics follow this one in the Cast:
on GetArtwork me
  set myStartArt to the number of member (the member of sprite spriteNum)
  set numberOfGraphics to 0
  repeat while the type of member (myStartArt + numberOfGraphics) = #bitmap
    set numberOfGraphics to numberOfGraphics + 1
  end repeat
end

--======  STANDARD BEHAVIOR HANDLERS:

on getPropertyDescriptionList me
  set theProps to [:]

  set c to "What causes sprite to rotate?"
  set f to #string
  set r to ["Align with sprite's motion", "Point to mouse", "Point at another sprite", "Time based"]
  set d to getAt(r,1)
  set typeProps to [#comment: c, #format: f, #range: r, #default: d]
  addProp theProps, #rotateType, typeProps

  set c to "If tracking sprite, which?"
  set f to #integer
  set d to 1
  addProp theProps, #spriteTarget, [#comment: c, #format: f, #default: d]

  set c to "If timebased, how many seconds?"
  set f to #float
  set d to 3
  addProp theProps, #rotationDuration, [#comment: c, #format: f, #default: d]

  return theProps
end

on getBehaviorDescription me
  set line1 to "   This behavior will rotate a sprite so that it is always¬
  aligned with its motion, or so it always points to the mouse or another¬
  sprite, or so that it rotates fully in a certain amount of time." &RETURN
  set line2 to "   It uses consecutive graphics in the Cast. These start¬
  from the upright position and proceed clockwise. End the sequence with an¬
  empty cast slot or a member which is not a graphic. Drag the first,¬
  upright, member to the Stage." & RETURN
  set line3 to "   (Example: Member 15 is an upright arrow. It is rotated¬
  360d in the Paint Window and AutoDistort is used to make 8 more members.¬
  Delete the duplicate upright arrow in slot 23. You now have 8 graphics in a¬
  row, rotating  clockwise.)" & RETURN
  set line4 to "   This behavior only affects the sprite's graphic, and so¬
  other simultaneous behaviors can affect motion, or handle mouse events,¬
  etc. It does not test for whether it is applied to a graphic." & RETURN
  set line5 to "   I hope the options are clear. I caught divide-by-zero¬
  errors and think the math is okay. There can be a flip if y=0. I haven't¬
  tested all options in all environments yet. Please let me know what I'm not¬
  seeing, okay? "
  return line1 & line2 & line3 & line4 & line5
end

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