RE: Rotating Graphics

[Jim Hurley]

Message: 3
Date: Fri, 5 Mar 2004 11:28:48 -0500
From: "Springer, Paul" <[EMAIL PROTECTED]>
Subject: RE: Rotating Graphics
To: 'How to use Revolution' <[EMAIL PROTECTED]>
Message-ID:
        <[EMAIL PROTECTED]>
Content-Type: text/plain
Dar,

Thanks for the help. As a beginner with RR, I need a little clarification.

1. When you say "Rotate that." Do you mean with a built in command or with a
custom command that is re-calculating where the points should be?
2. Aren't there points already defined for the polygons vertices? Do I need
to somehow use my custom properties instead of those?
-Paul

Hi Paul,

This is tricky stuff in the beginning.

What follows is a variation on something developed by the list. It 
avoids the rounding errors you have encountered, following Dar 
Scott's suggestion, by using a set of custom properties.

There are two components, setAngle and rotatePoly. The latter just 
sets the angle to the existing angle plus the degree of rotation.

You can script the construction of the custom properties, for example

   set the defaultPoints of grc "myPoly" to the points of grc "myPoly"
   set the pivotPoint of grc "myPoly" to line 1 of the points of 
graphic "myPoly"
   set the theAngle of grc "myPoly" to 0

On mouseUP
  --Rotate a polygon 8 times by an angle of 45 about a pivot point
   repeat 8
     rotatePoly "myPoly", 45
     wait 20 ticks --Slow it down so you can see it.
   end repeat
end mouseUP
On setAngle tGraphic, tAngle
  --Uses three custom properties of the polygon
  --1) A default angle called "theAngle" used to define the initial orientation
  --2) A set of default points used to define the initial shape: 
"defaultPoints"
  --3) A pivot point "pivotPoint"

  set the theAngle of grc tGraphic to tAngle
  put the defaultPoints of graphic tGraphic into tPoints
  put the pivotPoint of grc tGraphic into tPivot
  put item 1 of tPivot into xPivot
  put item 2 of tPivot into yPivot
  put empty into newPointList

  put sin(tAngle* pi/180) into S
  put cos(tAngle * pi/180) into C
  --Set points relative to pivot
  
  repeat for each line tLine in tPoints
    put (item 1 of tLine)- xPivot into theX
    put (item 2 of tLine)- yPivot into theY
    put round(C*theX+ S*theY + xPivot)& comma after rotPtlist
    put round(-S*theX + C*theY+  yPivot)after rotPtlist
    put return after rotPtList
  end repeat
  set the points of graphic tGraphic to rotPtlist
end setAngle

on rotatePoly tGraphic, tChange
  put the theAngle of grc tGraphic into tAngle
  setAngle tGraphic, tAngle+tChange
end rotatePoly
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