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rectangle contains point

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  rectangle contains point bob smith <bob@coolfone.comze.com> - 2012-10-05 12:00 -0700
    Re: rectangle contains point markspace <-@.> - 2012-10-05 12:20 -0700
    Re: rectangle contains point Eric Sosman <esosman@comcast-dot-net.invalid> - 2012-10-05 15:23 -0400
      Re: rectangle contains point bob smith <bob@coolfone.comze.com> - 2012-10-05 14:16 -0700
    Re: rectangle contains point Jeff Higgins <jeff@invalid.invalid> - 2012-10-05 15:43 -0400

#19139 — rectangle contains point

So, I have a rectangle class as follows:

public class My_Rectangle {
	double x, y, width, height;
	AffineTransform aft;

Anyone know a good strategy for checking if a point is in the rectangle?

The main difficulty is the transform.

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#19142

On 10/5/2012 12:00 PM, bob smith wrote:
> So, I have a rectangle class as follows:
>
> public class My_Rectangle {
> 	double x, y, width, height;
> 	AffineTransform aft;
>
> Anyone know a good strategy for checking if a point is in the rectangle?
>
> The main difficulty is the transform.


http://lmgtfy.com/?q=computational+geometery

Seriously, it's a big subject.  I don't have any easy answers.

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#19143

On 10/5/2012 3:00 PM, bob smith wrote:
> So, I have a rectangle class as follows:
>
> public class My_Rectangle {
> 	double x, y, width, height;
> 	AffineTransform aft;
>
> Anyone know a good strategy for checking if a point is in the rectangle?
>
> The main difficulty is the transform.

     I'll assume that x/y/width/height represent an untransformed
rectangle, and that you want to test whether the point is inside
the quadrilateral formed by transforming the rectangle with aft.
If that's the question, I see two approaches:

     - Transform the rectangle and represent the result as a
       Polygon, then use Polygon's contains() method.

     - Inverse-transform the point and test whether the transformed
       point is inside the original rectangle.

     If that's not the question, please explain more fully.

-- 
Eric Sosman
esosman@comcast-dot-net.invalid

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#19148

On Friday, October 5, 2012 2:23:18 PM UTC-5, Eric Sosman wrote:
> On 10/5/2012 3:00 PM, bob smith wrote:
> 
> > So, I have a rectangle class as follows:
> 
> >
> 
> > public class My_Rectangle {
> 
> > 	double x, y, width, height;
> 
> > 	AffineTransform aft;
> 
> >
> 
> > Anyone know a good strategy for checking if a point is in the rectangle?
> 
> >
> 
> > The main difficulty is the transform.
> 
> 
> 
>      I'll assume that x/y/width/height represent an untransformed
> 
> rectangle, and that you want to test whether the point is inside
> 
> the quadrilateral formed by transforming the rectangle with aft.
> 
> If that's the question, I see two approaches:
> 
> 
> 
>      - Transform the rectangle and represent the result as a
> 
>        Polygon, then use Polygon's contains() method.
> 
> 
> 
>      - Inverse-transform the point and test whether the transformed
> 
>        point is inside the original rectangle.
> 
> 
> 
>      If that's not the question, please explain more fully.
> 
> 
> 
> -- 
> 
> Eric Sosman
> 
> esosman@comcast-dot-net.invalid

Excellent ideas.  I went with inverse transform, and it works.

Thanks.

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#19144

On 10/05/2012 03:00 PM, bob smith wrote:
> So, I have a rectangle class as follows:
>
> public class My_Rectangle {
> 	double x, y, width, height;
> 	AffineTransform aft;
>
> Anyone know a good strategy for checking if a point is in the rectangle?
>
> The main difficulty is the transform.
John B. Matthews provided a strategy for this
in a reply to another of your recent posts.

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