mouse within oval filled area

Pierre Sahores sc at sahores-conseil.com
Sun Nov 13 02:40:44 EST 2011

```James,

"Magnifique*!

Pierre

Le 13 nov. 2011 à 07:01, James Hurley a écrit :

> Hugh,
>
> Would this help? The script below will draw a polygon that looks like an ellipse with a start and stop angle.
>
> The trouble with the start angle and the arcangle in RR is that they are not polar angles but are related in a complex way:
>
> arcAngle = arctangent( b/a * tangent(polarangle)
>
>
> And then use a mousewithin handler for the "oval" grc--actually a polygon
>
>
> local a,b
>
> on mouseUp
>   put 10 into tStartAngle -- Or whatever
>   put 250 into tEndAngle -- Or whatever
>   put 200 into a --Semi major axis
>   put 100 into b -- Semi minor axis
>   put 300 into x0 -- The origin
>   put 250 into y0 -- The origin
>   put x0,y0 & cr into tPoints
>   --Construct the points for the ellipse
>   repeat with i = tStartANgle to tEndANgle
>      put  r(i) into tR
>      put round ( x0 + r(i) * cos(i*pi/180)), round(y0+r(i) * sin(i*pi/180)) into temp
>      put temp & cr after tPoints
>   end repeat
>
>   put x0,y0 after tPoints
>   --Construct the graphic
>   if there is no grc "oval" then create grc "oval"
>   set the style of grc "oval" to "polygon"
>   set the opaque of grc "oval" to true
>   set the points of grc "oval" to tPoints
> end mouseUp
>
>
> function r tA --Radial distance to the ellipse as afunction of the angle
>   put (cos(tA*pi/180))^2 / (a*a) + (sin(tA*pi/180))^2 / (b*b) into temp
>   return 1/sqrt(temp)
> end r
>
>> Has anyone worked out how to test if the mouseLoc is within the filled area
>> of an oval graphic (defined by startAngle and arcAngle)? I was thinking
>> polar coordinates, but this assumes a circle and a fixed radius which is not
>> necessarily the case. A btter math brain than mine is needed!
>>
>> Hugh Senior
>> FLCo
>
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--
Pierre Sahores
mobile : 06 03 95 77 70
www.sahores-conseil.com

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