I want to draw multiple polygons as though they

are the same curve. My current approach is

as follows. Make a new polygon that is constructed

by adding the first point to each polygon, then

append all these polygons, followed in opposite

order by the first points of each polygon.

I then make a copy of the current pen and set

the pen to transparant and use the above result

as argument to DrawPolygon. I then restore the

pen, copy the brush and set it to transparant

and call DrawPolygon with the original polygons.

after which I restore the brush.

This is all rather involved so I was wondering

if there is a better way to tangle this problem.

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--

Antoon Pardon

Antoon Pardon <Antoon.Pardon@rece.vub.ac.be> writes:

I want to draw multiple polygons as though they

are the same curve. My current approach is

as follows. Make a new polygon that is constructed

by adding the first point to each polygon, then

append all these polygons, followed in opposite

order by the first points of each polygon.

I then make a copy of the current pen and set

the pen to transparant and use the above result

as argument to DrawPolygon. I then restore the

pen, copy the brush and set it to transparant

and call DrawPolygon with the original polygons.

after which I restore the brush.

FWIW, that's pretty exactly what I did in Thuban

(http://thuban.intevation.org/). I don't think there's a simpler way.

Bernhard

## ···

--

Intevation GmbH http://intevation.de/

Sketch http://sketch.sourceforge.net/

MapIt! http://www.mapit.de/

Bernhard Herzog wrote:

Antoon Pardon <Antoon.Pardon@rece.vub.ac.be> writes:

> I want to draw multiple polygons as though they

> are the same curve.

FWIW, that's pretty exactly what I did in Thuban

(http://thuban.intevation.org/). I don't think there's a simpler way.

It sounds like the issue may be settled, but I, for one, am totally

confused about what it is you want to do!

What does "as though they are the same curve" mean? I'm afraid even with

your descriptin of a solution, I have no idea what hte result would be.

Care to make another attempt at an explaination?

-Chris

## ···

--

Christopher Barker, Ph.D.

Oceanographer

NOAA/OR&R/HAZMAT (206) 526-6959 voice

7600 Sand Point Way NE (206) 526-6329 fax

Seattle, WA 98115 (206) 526-6317 main reception

Chris.Barker@noaa.gov

Well if you draw a polygon, it is the winding rule that decides whether

a particular point will be colored or not. What I want is that the

winding rule is applied to multiple polygon. The result is that for

instance the intersection of two polygons will not be colored. This

can be very usefull if you want to draw a shape with holes in it.

## ···

On Tue, Nov 26, 2002 at 03:41:47PM -0800, Chris Barker wrote:

Bernhard Herzog wrote:

>

> Antoon Pardon <Antoon.Pardon@rece.vub.ac.be> writes:

>

> > I want to draw multiple polygons as though they

> > are the same curve.

> FWIW, that's pretty exactly what I did in Thuban

> (http://thuban.intevation.org/). I don't think there's a simpler way.

It sounds like the issue may be settled, but I, for one, am totally

confused about what it is you want to do!

What does "as though they are the same curve" mean? I'm afraid even with

your descriptin of a solution, I have no idea what hte result would be.

Care to make another attempt at an explaination?

--

Antoon Pardon

Antoon Pardon wrote:

> What does "as though they are the same curve" mean? I'm afraid even with

> your descriptin of a solution, I have no idea what hte result would be.

> Care to make another attempt at an explaination?

>

Well if you draw a polygon, it is the winding rule that decides whether

a particular point will be colored or not. What I want is that the

winding rule is applied to multiple polygon. The result is that for

instance the intersection of two polygons will not be colored. This

can be very usefull if you want to draw a shape with holes in it.

Thanks, I get it now, and I certainly can't come up with anything more

elegant that what you already have. I may in fact borrow your idea at

some point.

thanks,

-Chris

## ···

--

Christopher Barker, Ph.D.

Oceanographer

NOAA/OR&R/HAZMAT (206) 526-6959 voice

7600 Sand Point Way NE (206) 526-6329 fax

Seattle, WA 98115 (206) 526-6317 main reception

Chris.Barker@noaa.gov