Geometry Boost List: [ggl] Re: Help needed with Intersection operation

Subject: [ggl] Re: Help needed with Intersection operation
From: Barend Gehrels (barend)
Date: 2011-08-28 23:16:49

Hi Christophe,

On 20-8-2011 0:13, Christoph Keller wrote:
> Hello Angus,
>
> thanks for providing the code. However if I do that using double 
> precision, i get a triangle as output, that has little to do with the 
> intersection.
>
> I made a mistake posting my Data. One element had a different value. I 
> also used correct, as you suggested, but as I expected this changes 
> nothing.
>
> I posted my complete code below. Note that the y-value 
> 29.884635544079821 cannot belong to the first polygon.

Right, it indeed should not. Though the output triangle in general 
represents the (more or less) right difference, it is apparently not 
precise enough for your purposes. If you use ttmath, you will get the 
(more) correct output. I will see if it can be improved for double as well.

>
> So it seems we found two errors.

It is unclear to me which is the other error.

> The question for me is if I should develop my own intersection code?

That is not the intention.

Regards, Barend

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