CGAL users discussion list

["Kenneth Tham" <>]

Hi,
    Attached is my code that gives the error. The error occurs when the join 
function is called. I have commented out the code that checks for orientation 
of the Polygon Q as that also gives an error. The interesting thing is that 
if the first three points are not added in Polygon Q, the resulting polygon 
is anti-clockwise oriented. But when the 3 points are added, it cannot pass 
the checking. Thanks for your help.
 
Regards,
Kenneth
 

        -----Original Message----- 
        From: 

 on behalf of Ophir Setter 
        Sent: Thu 2/14/2008 4:53 PM 
        To: 

 
        Cc: 
        Subject: Re: [cgal-discuss] CGAL::join Function
        
        
        What number type? - You shoiuld use a kernel that supports exact 
construction and exact predicates.
        
        I think the best way is if you send code and data that creates the 
bug.
        
        
        On Thu, Feb 14, 2008 at 10:45 AM, Kenneth Tham 
<>
 wrote:
        

                Hi,
                    I am using a Kernel class inheriting from 
CGAL::Cartesian<Number_type>.
                Regards,
                Kenneth
                 

                        -----Original Message-----
                        From: 

 
[mailto:]On
 Behalf Of Ophir Setter
                        Sent: Thursday, February 14, 2008 3:41 PM
                        To: 

                        Subject: Re: [cgal-discuss] CGAL::join Function
                        
                        
                        Can send the code that generates the code? 
                        What kernel are you using?
                        Can you send the data that causes this assertion?
                        
                        
                        
                        On Thu, Feb 14, 2008 at 8:47 AM, Kenneth Tham 
<>
 wrote:
                        

                                Hi,
                                  Thanks for your help. I am now trying to 
debug the algorithm for joining the polygons. There is one case where it 
needs to merge about 300 polygons. After about 200 times, the program gives 
the error as shown in the attached file. I'm not really sure what it means. 
Can anybody help? Thanks.
                                Regards,
                                Kenneth
                                



                                -----Original Message-----
                                From: Efi Fogel 
[mailto:]
                                Sent: Tuesday, February 12, 2008 10:23 PM
                                To: 

                                Subject: Re: [cgal-discuss] CGAL::join 
Function
                                
                                
                                Kenneth Tham wrote:
                                
                                >Hi,
                                >    I am using the CGAL::join function for 
joining polygon_with_holes_2 objects. In my program, I use the join function 
for about 10000 times consequtively(trying to join a polygon to a set of 
polygons). My program takes quite a long time to process this part ( several 
minutes ). Is it normal for this function to take this amount of time? Thanks.
                                >Regards,
                                >Kenneth
                                >
                                >
                                >
                                First of all you should call the join 
function just once with a range of
                                input polygons (or polygons with holes). If 
you intend to perform other
                                operations in a sequence, you should call the 
join member function of
                                Polygon_set_2 instead of the global join 
function. Finally, I assume you
                                are using a exact-prediacte 
exact-construction kernel (for a good
                                reason). This means that all operations are 
caried out in an exact
                                maner. You can try to expedite the 
computation by reducing the bit
                                length of the input coordinates.
                                
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