Added PickVertSW to offer an alternative for selection for hw that does not support opengl selection

wrap/gl/pick.h

@@ -60,6 +60,54 @@ public:
     fi=NULL;
     return false;
   }
+
+   static Point3f Proj(const Eigen::Matrix4f &M, const float * viewport, Point3f &p)
+   {
+     const float vx=viewport[0];
+     const float vy=viewport[1];
+     const float vw2=viewport[2]/2.0f;
+     const float vh2=viewport[3]/2.0f;
+     Eigen::Vector4f vp(p[0],p[1],p[2],1.0f);
+     Eigen::Vector4f vpp = M*vp;
+     Eigen::Vector4f ndc = vpp/vpp[3];
+
+     Point3f sc(
+         vw2*ndc[0] + vx+vw2,
+         vh2*ndc[1] + vy+vh2,
+         ndc[2]
+         );
+
+     return sc;
+   }
+
+   static int PickVertSW(int x, int y, MESH_TYPE &m, std::vector<VertexPointer> &result, int width=4, int height=4,bool sorted=true)
+   {
+     result.clear();
+     Eigen::Matrix4d mp,mm;
+     Eigen::Matrix4f M;
+     GLint viewport[4];
+     Box2f reg;
+     reg.Add(Point2f(x-width/2.0f,y-height/2.0f));
+     reg.Add(Point2f(x+width/2.0f,y+height/2.0f));
+     glGetIntegerv(GL_VIEWPORT,viewport);
+     float viewportF[4];
+     for(int i=0;i<4;++i) viewportF[i]=viewport[i];
+
+     glGetDoublev(GL_PROJECTION_MATRIX ,mp.data());
+     glGetDoublev(GL_MODELVIEW_MATRIX,mm.data());
+     M = (mp*mm).cast<float>();
+     for(VertexIterator vi=m.vert.begin();vi!=m.vert.end();++vi)if(!vi->IsD())
+     {
+       Point3f pp = Proj(M,viewportF,vi->P());
+       if(pp[0]<reg.min[0]) continue;
+       if(pp[0]>reg.max[0]) continue;
+       if(pp[1]<reg.min[1]) continue;
+       if(pp[1]>reg.max[1]) continue;
+       result.push_back(&*vi);
+     }
+     return result.size();
+   }
+
   static int PickVert(int x, int y, MESH_TYPE &m, std::vector<VertexPointer> &result, int width=4, int height=4,bool sorted=true)
   {
       result.clear();