Re: [boost] interest on a geometry library

From: rodolfo_at_[hidden]
Date: 2006-03-23 11:57:08

On Thu, Mar 23, 2006 at 10:51:42AM +0100, Theodore Papadopoulo wrote:
> On Wed, 2006-03-22 at 21:52 +0100, Janek Kozicki wrote:
> Euclidean::Point<N>
> Euclidean::Line<N>           // not very different from projective
> line ??
> Euclidean::SemiLine<N>
> Euclidean::Segment<N>
> Euclidean::Simplex<N>

I like this way of representing them. And for instance, Point<2> can
be a specialization that adds members x and y, them being references to
coord[0] and coord[1], same thing with Point<3>.

As those geometry classes are (and will) be used a lot, the main usage
should be kept trivial and simple (or as others may say: KISS methodology).

using namespace euclidean;

template <unsigned D, class T>
struct point
{
    T coord[D]; // someone wrote about a smallvector type... 
};

template <class T>
struct point<2, T>
{
    point() : x(coord[0]), y(coord[1]) {}
    point(const T &_x, const T &_y) : x(coord[0]=_x), y(coord[1]=_y) {}
    T coord[2];
    T &x, &y;
};

something similar for rects

template <unsigned D, class T>
point<D, T> cross(const point<D, T> &pt1, const point<D, T> &pt2)
{
    return // cross product, we should add specializations for each
           // dimension
}

template <unsigned D, class T>
T dot(const point<D, T> &pt1, const point<D, T> &pt2)
{
    return // same thing, specializations for each dimension
}

point<2,double> pt1(3,4); point<2> pt2(5,6);
point<2,double> pt3 = cross(pt1, pt2);
double d = dot(pt2, pt3);
rect<2,double> rc(p2, pt3);
double a = rc.area(); // or area(rc)?

[]s
Rodolfo Lima

                
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