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[Yue Biek <>]

Hello,

This time I used the Lazy_exact type for my Point class,but I met problems once more,the problems are discribed as follows.

The Point Class  in my code is:

Class MyPoint

{ 

private:

MP_FT pos[2]; //used to store x and y coordinate 

public:

       MP_FT & x() {return *pos;}

}

I used the following code to show my problem. in main function:

int main()

{

        Point p(0.1, 0.2);

MP_FT x = p.x();

std::cout << p.x() << std::endl;

}

but the code show faults:the wrong place is in Interval_nt.h and the code is:

bool is_point() const

 {

    return sup() == inf();

 }

Thank you!

2011/5/13 Efraim Fogel <>

You need to use exact-predicate and exact-construction kernel.
When you attach code, attach it in a way that it can be compiled and executed, and perhaps even read by a human being.

Yue Biek wrote:

My OS is win7(32bit) and environment is  VS2008,When I used the MinKowski_2 in CGAL_3.8, I found the Union operation of two Boundarys is something wrong.

the function are usd in Minkowski_sum_decomp_2.h
*The exact line is :*
sum_holes = unite(boundary_segments.begin(), boundary_segments.end(),sum_bound, sum_holes);

My target is to morph between two non-convex but simple polygons.
At first,when I morph between a triangle and a rectangle,the "unite" operation is right.and the morph process is right.
However,when the input are two non-convex polygons(PandQ.dat),though the MinKowski sums of the two polygons can be calcuated, the "unite" operation are something wrong. when the input are two non convex polygons, the "unite" operation are right the in the first time,but in the second time ,it fails.

Part of source code are here,Polygon P and Polygon Q are defined before hand,and they are all non-convex and simple(PandQ.dat).

    glClear(GL_COLOR_BUFFER_BIT);
float delt=0.11;
while(true)
{
for(float t=0.1;t<=0.9;t+=delt)
{
glClear(GL_COLOR_BUFFER_BIT);
Polygon s_temp;
Polygon t_temp;

for(size_t i=0;i!=P.size();i++)
{
double temp_x=P[i].x()*(1-t);
double temp_y=P[i].y()*(1-t);
Point temp_p(temp_x,temp_y);
s_temp.push_back(temp_p);
}

for(size_t i=0;i!=Q.size();i++)
{
double temp_x=Q[i].x()*t;
double temp_y=Q[i].y()*t;
Point temp_p(temp_x,temp_y);
t_temp.push_back(temp_p);
}

Polygon_with_holes sum=minkowski_sum_2(s_temp,t_temp,ssab_decomp);
                                                               std::cout << "P = "; print_polygon (s_temp);
std::cout << "Q = "; print_polygon (t_temp);
std::cout << "P (+) Q = ";print_polygon(sum.outer_boundary());

if(!sum.is_unbounded())
{
glBegin(GL_LINE_LOOP);
for(Polygon::iterator cur=sum.outer_boundary().vertices_begin();cur!=sum.outer_boundary().vertices_end();cur++)
{
 glVertex2f(cur->x(),cur->y());
}
glEnd();
glFlush();
}
else
{
for (Polygon_with_holes::Hole_iterator iter=sum.holes_begin();iter!=sum.holes_end();++iter)
{
Polygon::iterator piter=iter->vertices_begin();
glBegin(GL_LINE_LOOP);
for(;piter!=iter->vertices_end();piter++)
{
double temp_x=piter->x();
double temp_y=piter->y();
glVertex2f(temp_x,temp_y);
}
glEnd();
}
}
sum.clear();
s_temp.clear();
t_temp.clear();
if(s_temp.is_empty())
{
cout<<"empty "<<endl;
}
if(t>1.0||t<0.1)
{
delt=-delt;
}
}
}

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