double CMinimizerBase::LineMinimizer(CNumVec &position, double dist0, const CNumVec &direction, bool roughly)
{
LM_direction=&direction;
LM_start_pos=&position;
double pleft, pmin, pright, pnext;
double dleft, dmin, dright, dnext;
pleft=0;
dleft=dist0;
pnext=1;
dnext=LineDistance(pnext);
if(dleft<dnext) // minimum is less than precision (= gradient norm) deep
return(dist0);
// try to bracket a minimum along "direction"
pmin=pleft;
dmin=dleft;
do
{
pleft=pmin;
dleft=dmin;
pmin=pnext;
dmin=dnext;
pnext*=2;
dnext=LineDistance(pnext);
}
while(dmin>dnext);
if(roughly && pmin>50) // stops exact determination if minimum is far from optimal value
{
CNumVec p=direction;
p*=pleft;
position+=p;
return(dmin);
}
pright=pnext;
dright=dnext;
// Further bracket minimum using "GoldenCut"
// Ideally this should be replaced by some function taking into account the
// pretty good reproducible function along the line minimization
bool longer_interval_right=true;
while(pright-pleft>1.0)
{
if(longer_interval_right)
{
pnext=pmin+(pright-pmin)*0.38;
dnext=LineDistance(pnext);
if(dnext<dmin)
{
pleft=pmin;
dleft=dmin;
pmin=pnext;
dmin=dnext;
}
else
{
pright=pnext;
dright=dnext;
longer_interval_right=false;
}
}
else
{
pnext=pmin+(pleft-pmin)*0.38;
dnext=LineDistance(pnext);
if(dnext<dmin)
{
pright=pmin;
dright=dmin;
pmin=pnext;
dmin=dnext;
}
else
{
pleft=pnext;
dleft=dnext;
longer_interval_right=true;
}
}
}
// Change 'position to Minimum position
CNumVec p=direction;
p*=pmin;
position+=p;
return(dmin);
}
int
checkwalls( World *w, View *v )
{
extern fixed view_height;
Wall *wall = (Wall *) w->walls->table, *mem_wall;
double x1, y1, tmp, min = 512.0;
int i;
x1 = FIXED_TO_FLOAT(v->x);
y1 = FIXED_TO_FLOAT(v->y);
if ( x1 == x && y1 == y )
return DONT_INTERSECT;
for (i = 0; i < TABLE_SIZE(w->walls); i++, wall++ ) {
/* Check Distance */
tmp = LineDistance( x1, y1,
FIXED_TO_FLOAT(wall->vertex1->x ),
FIXED_TO_FLOAT(wall->vertex1->y ),
FIXED_TO_FLOAT(wall->vertex2->x ),
FIXED_TO_FLOAT(wall->vertex2->y ) );
if ( fabs(tmp) < fabs( min ) )
{
min = tmp;
mem_wall = wall;
}
}
/* is there any point in checking further. */
if ( fabs( min ) < VECTOR_LEN )
{
/* start examine the wall */
fixed ceiling, floor;
/* Check the outher side of the object */
if ( min > 0.0 )
{
floor = mem_wall->front->floor;
ceiling = mem_wall->front->ceiling;
}
else
{
floor = mem_wall->back->floor;
ceiling = mem_wall->back->ceiling;
}
/* if the stair is less than FIXED_ONE_QUARTER and the
head has goes free and there are enought room. */
if ( FIXED_ONE_QUARTER >= (floor-v->height) && ( ceiling > v->height ) &&
( MAN_SIZE <= (ceiling-floor) ) ) {
if ( s_wall != mem_wall || ( min > 0.0 && side <= 0.0 ) ||
(min <= 0.0 && side > 0.0 ) )
{
if ( min < 0.0 )
view_height = mem_wall->front->floor+MAN_SIZE;
else
view_height = mem_wall->back->floor+MAN_SIZE;
s_wall = mem_wall;
}
}
else
/* am i running towards the wall? */
if ( fabs( min ) < fabs( side ) )
{
s_wall = mem_wall;
slide_wall( &x, &y, x1, y1, side, min );
v->x = FLOAT_TO_FIXED( x );
v->y = FLOAT_TO_FIXED( y );
return 0;
}
}
side = min;
x = x1;
y = y1;
return 0;
}