void NBodyWorldApp::pickParticle( Particle2D*& picked ){
Particle2D* screenObjects[256];
// mouse picking
double rmax = 2.0d;
double r2max = rmax*rmax;
Vec2d vmouse;
vmouse.set( mouse_begin_x, mouse_begin_y );
UINT mfound = world.map.getObjectsInRect( (float)(vmouse.x - rmax ), (float)(vmouse.y - rmax ), (float)(vmouse.x + rmax ), (float)(vmouse.y + rmax ), &(screenObjects[0]) );
//printf( "mfound %i \n", mfound );
int imin = -1;
double r2min = 1e+300;
for( int i=0; i<mfound; i++ ){
Particle2D* p = screenObjects[i];
Vec2d d;
d.set_sub( p->pos, vmouse );
double r2 = d.norm2();
if( r2 < r2max ){
if( r2 < r2min ){ r2min = r2; imin = i; }
}
//printf( " r2 %3.3f r2max %3.3f r2min %3.3f imin %i \n", r2, r2max, r2min, imin );
}
if( imin >= 0 ){
picked = screenObjects[imin];
}else{
picked = NULL;
}
//if( world.picked != NULL ) printf( " MOUSE picked (%f,%f) \n", world.picked->pos.x, world.picked->pos.y );
}
int MoleculeWorldApp::pickMol( const Vec2d& mpos ){
int imin = -1;
double r2min = 1e+300;
for(int i=0; i<world.nMols; i++){
Vec2d d; d.set_sub( mpos, world.pos[i] );
double r2 = d.norm2();
if (r2<r2min){ r2min=r2; imin=i; }
}
return imin;
}