source: GTP/trunk/Lib/Geom/shared/GTGeometry/src/libs/gfx/geom/3D.h @ 1025

#ifndef GFXGEOM_3D_INCLUDED // -*- C++ -*-
#define GFXGEOM_3D_INCLUDED

#include <gfx/math/Vec3.h>
#include <gfx/math/Vec4.h>
#include <gfx/tools/Array.h>

//
// Generally useful geometric functions
//

namespace simplif
{
        extern Vec3 randomPoint(const Vec3&, const Vec3&);  // on segment
        extern Vec3 randomPoint(const Vec3&, const Vec3&, const Vec3&); // in triangle

        extern real triangleArea(const Vec3&, const Vec3&, const Vec3&);
        extern real triangleCompactness(const Vec3&, const Vec3&, const Vec3&);

        class Bounds
        {
        public:

                Vec3 min, max;
                Vec3 center;
                real radius;
                unsigned int points;

                Bounds() { reset(); }

                void reset();
                void addPoint(const Vec3&);
                void complete();
        };

        class Plane
        {
                //
                // A plane is defined by the equation:  n*p + d = 0
                Vec3 n;
                real d;

        public:

                Plane() : n(0,0,1) { d=0; } // -- this will define the XY plane
                Plane(const Vec3& p, const Vec3& q, const Vec3& r) { calcFrom(p,q,r); }
                Plane(const array<Vec3>& verts) { calcFrom(verts); }
                Plane(const Plane& p) { n=p.n; d=p.d; }

                void calcFrom(const Vec3& p, const Vec3& q, const Vec3& r);
                void calcFrom(const array<Vec3>&);

                bool isValid() const { return n[X]!=0.0 || n[Y]!=0.0 || n[Z]!= 0.0; }
                void markInvalid() { n[X] = n[Y] = n[Z] = 0.0; }

                real distTo(const Vec3& p) const { return n*p + d; }
                const Vec3& normal() const { return n; }

                void coeffs(real *a, real *b, real *c, real *dd) const {
                        *a=n[X]; *b=n[Y]; *c=n[Z]; *dd=d;
                }
                Vec4 coeffs() const { return Vec4(n,d); }
        };


        //
        // A triangular face in 3D (ie. a 2-simplex in E3)
        //
        class Face3
        {
        protected:
                Plane P;

        private:
                void recalcPlane() { P.calcFrom(vertexPos(0),vertexPos(1),vertexPos(2)); }
                void recalcPlane(const Vec3& a,const Vec3& b,const Vec3& c)
                { P.calcFrom(a,b,c); }

        public:
                Face3(const Vec3& a,const Vec3& b,const Vec3& c)
                : P(a,b,c)
                { }

                //
                // Basic primitive operations on faces
                virtual const Vec3& vertexPos(int i) const = 0;
                virtual void vertexPos(int i, const Vec3&) = 0; 
                const Plane& plane() { if(!P.isValid()) recalcPlane();   return P;}
                void invalidatePlane() { P.markInvalid(); }

                real distTo(const Vec3& p) const;
                real area();
        };
}



// GFXGEOM_3D_INCLUDED
#endif