/// <summary>
/// Maintain halfspaces in ascending opening angle order
/// Called after each add, which puts a new halfspace at the
/// end of the arraylist. "Bubble" the new addition to its proper
/// place. Also assign a "Sign" from to this Convex
/// One of: Positive, negative, zero, mixed.
/// </summary>
/// <param name="sign">The sign of the most recently added halfspace</param>
private void sortandsign(Halfspace.Sign sign) {
int i;
int cnt;
Halfspace hs;
Halfspace hsprev;
Object o;
cnt = _halfspaces.Count;
for(i = cnt-1; i>0; i--){
hs = (Halfspace) _halfspaces[i];
hsprev = (Halfspace) _halfspaces[i-1];
if (hs.hangle > hsprev.hangle){
// New halfspace has wider angle than previous one
// so we are done!
break;
} else {
// new halfspace needs to trade places with previous one
o = hsprev;
_halfspaces[i-1] = hs;
_halfspaces[i] = o;
}
} // Done sorting, now update sign
if(cnt == 1){
this._sign = sign;
return;
}
switch(this._sign){
case Halfspace.Sign.Negative:
if (sign == Halfspace.Sign.Positive)
this._sign = Halfspace.Sign.Mixed;
break;
case Halfspace.Sign.Positive:
if (sign == Halfspace.Sign.Negative)
this._sign = Halfspace.Sign.Mixed;
break;
case Halfspace.Sign.Zero:
this._sign = sign;
break;
case Halfspace.Sign.Mixed:
// Mixed stays mixed
break;
}
}
private void prune() {
// NEW: Check if this halfspace is the whole sphere, if so, remove it.
int clen = _halfspaces.Count;
bool hasPositive = false;
bool hasNegative = false;
bool hasZero = false;
bool[] removethese = new bool[clen];
bool removeall = false;
if (clen < 1)
return;
for (int i = 0; i < clen; i++) {
Halfspace hi = (Halfspace)_halfspaces[i];
removethese[i] = false;
if (clen > 1 && hi.isUniversal()) {
// _halfspaces.RemoveAt(i);
removethese[i] = true;
}
if (hi.isNull()) {
removeall = true;
break;
}
}
if (removeall) {
_halfspaces.Clear();
hasZero = true; // force consistency.
} else {
for (int i = clen - 1; i >= 0; i--) {
if (removethese[i]) {
_halfspaces.RemoveAt(i);
} else {
Halfspace hi = (Halfspace)_halfspaces[i];
switch (hi.sign) {
case Halfspace.Sign.Negative: hasNegative = true; break;
case Halfspace.Sign.Positive: hasPositive = true; break;
case Halfspace.Sign.Zero: hasZero = true; break;
}
}
}
}
if (hasPositive && hasNegative) {
_sign = Halfspace.Sign.Mixed;
} else if (hasPositive) {
_sign = Halfspace.Sign.Positive;
} else if (hasNegative) {
_sign = Halfspace.Sign.Negative;
} else {
_sign = Halfspace.Sign.Zero;
}
if (_sign == Halfspace.Sign.Zero && !hasZero) {
throw new Exception("Convex.prune() internal inconsistency");
}
// end new.
}
private void init(){
_halfspaces = new ArrayList(); // will change
_corners = new ArrayList();
_sign = Halfspace.Sign.Zero;
_boundingCircle = new Halfspace();
_htm = new HtmTrixel();
}
private void clear(){
_halfspaces = null;
_corners = null;
_sign = Halfspace.Sign.Zero;
_boundingCircle = null;
_htm = new HtmTrixel();
}
public void OLDsimplify() {
prune(); // remove redundant halfspaces, adjust sign.
if (_halfspaces.Count < 1)
return;
if (_sign == Halfspace.Sign.Zero) {
simplify0(); // treat ZERO convexes separately
return;
}
int i, j;
int clen;
bool redundancy = true;
while (redundancy) {
redundancy = false;
clen = _halfspaces.Count;
for (i = 0; i < clen; i++) {
Halfspace hi = (Halfspace)_halfspaces[i];
for (j = 0; j < i; j++) {
Halfspace hj = (Halfspace)_halfspaces[j];
Halfspace.Position iPosj;
// don't bother with two zero constraints
if (hi.sign == Halfspace.Sign.Zero &&
hj.sign == Halfspace.Sign.Zero)
continue;
// both pos or zero
if ((hi.sign == Halfspace.Sign.Positive
|| hi.sign == Halfspace.Sign.Zero) &&
(hj.sign == Halfspace.Sign.Positive ||
hj.sign == Halfspace.Sign.Zero)) {
// was: if ( (iPosj = testConstraints(i,j)) == 0 ) continue; // intersection
if ((iPosj = hi.relativePosition(hj)) == Halfspace.Position.Intersecting) continue;
if (iPosj == Halfspace.Position.Disjoint) { // disjoint ! convex is empty
_halfspaces.Clear();
return;
}
// one is redundant
if (iPosj == Halfspace.Position.Surrounds) {
// was: constraints_.erase(constraints_.en d()-i-1);
// was later:constraints_.erase(constraints_.begin()+i);
_halfspaces.RemoveAt(i);
} else if (iPosj == Halfspace.Position.Contained) {
// was: constraints_.erase(constraints_.en d()-j-1);
// later: was constraints_.erase(constraints_.begin()+j);
_halfspaces.RemoveAt(j);
} else
continue; // intersection
redundancy = true; // we did cut out a constraint -> do the loop again
break;
}
// both neg
if ((hi.sign == Halfspace.Sign.Negative) &&
(hj.sign == Halfspace.Sign.Negative)) {
//was: if ( (iposj = testConstraints(i,j)) <= 0 ) continue; // ok
iPosj = hi.relativePosition(hj);
if (iPosj == Halfspace.Position.Intersecting || iPosj == Halfspace.Position.Disjoint)
continue;
// one is redundant
if (iPosj == Halfspace.Position.Surrounds) {
//was: constraints_.erase(constraints_.en d()-1-j);
// later was:constraints_.erase(constraints_.begin()+j);
_halfspaces.RemoveAt(j);
} else if (iPosj == Halfspace.Position.Contained) {
//was : constraints_.erase(constraints_.en d()-1-i);
// later was: constraints_.erase(constraints_.begin()+i);
_halfspaces.RemoveAt(i);
} else
continue; // intersection
redundancy = true; // we did cut out a constraint -> do the loop again
break;
}
// one neg, one pos/zero
// was:if( (iposj = testConstraints(i,j)) == 0) continue; // ok: intersect
if ((iPosj = hi.relativePosition(hj)) == Halfspace.Position.Intersecting)
continue;
if (iPosj == Halfspace.Position.Disjoint) { // neg is redundant
if (hi.sign == Halfspace.Sign.Negative) {
//was: constraints_.erase(constraints_.en d()-1-i);
//was later:constraints_.erase(constraints_.begin()+i);
_halfspaces.RemoveAt(i);
} else {
//was: constraints_.erase(constraints_.en d()-1-j);
// was later: constraints_.erase(constraints_.begin()+j);
_halfspaces.RemoveAt(j);
}
redundancy = true; // we did cut out a constraint -> do the loop again
break;
}
// if the negative constraint is inside the positive: continue
if ((hi.sign == Halfspace.Sign.Negative && iPosj == Halfspace.Position.Contained) ||
(hj.sign == Halfspace.Sign.Negative && iPosj == Halfspace.Position.Surrounds))
continue;
// positive constraint in negative: convex is empty!
_halfspaces.Clear();
return;
} // for (i...)
if (redundancy) break;
}
}// while(redundancy)
// reset the sign of the convex
_sign = ((Halfspace)_halfspaces[0]).sign;
for (i = 1; i < _halfspaces.Count; i++) {
Halfspace hi = (Halfspace)_halfspaces[i];
switch (_sign) {
case Halfspace.Sign.Negative:
if (hi.sign == Halfspace.Sign.Positive)
_sign = Halfspace.Sign.Mixed;
break;
case Halfspace.Sign.Positive:
if (hi.sign == Halfspace.Sign.Negative)
_sign = Halfspace.Sign.Mixed;
break;
case Halfspace.Sign.Zero:
_sign = hi.sign;
break;
case Halfspace.Sign.Mixed:
break;
}
}
if (_halfspaces.Count == 1) // for one constraint, it is itself the BC
_boundingCircle.copy((Halfspace)_halfspaces[0]);
else if (_sign == Halfspace.Sign.Positive)
_boundingCircle.copy((Halfspace)_halfspaces[0]);
}
//// ////////////////////////// SIMPLIFICATION /////////////////////
//
//
// ///////////SIMPLIFY/////////////////////////////////////
// simplify:
//
/// <summary>
/// We have the following decision tree for the
/// simplification of convexes:
///
/// Always test two constraints against each other. We have
///
/// * If both halfspaces are Positive or Zero
/// # If they intersect: keep both
/// # If one lies inside the other: drop the *larger* one
/// # Else: disjunct. Clear the convex, stop.
///
/// * If both constraints are Negative
/// # If they intersect or are disjunct: ok
/// # Else: one lies in the other, drop smaller 'hole'
///
/// * Mixed: one Positive one Negative
/// # No intersection, disjunct: Positive is redundant
/// # Intersection: keep both
/// # POS inside NEG: empty convex, stop.
/// # NEG inside POS: keep both.
/// Eliminate reduntand Halfspaces
///
/// Simplification eliminates redundant Halfspaces.
/// For example, a halfspace that completely surrounds
/// another halfspace is eliminated. If two halfspaces
/// in the Convex are disjoint, then the Convex is empty
/// </summary>
public void simplify() {
prune(); // remove redundant halfspaces, adjust sign.
if (_halfspaces.Count < 1)
return;
if(_sign == Halfspace.Sign.Zero) {
simplify0(); // treat zERO convexes separately
return;
}
int i,j;
int clen;
bool restart = true;
while(restart) {
restart = false;
clen = _halfspaces.Count;
for(i = 0; i < clen; i++) {
Halfspace hi = (Halfspace) _halfspaces[i];
for (j = 0; j < i; j++) {
Halfspace hj = (Halfspace)_halfspaces[j];
Halfspace.Position iPosj;
// don't bother with two zero constraints
if (hi.sign == Halfspace.Sign.Zero &&
hj.sign == Halfspace.Sign.Zero)
continue;
// No longer need to look at sign of halfspace, relativeposition does the work
iPosj = hi.relativePosition(hj);
if (iPosj == Halfspace.Position.Intersecting)
continue;
if (iPosj == Halfspace.Position.Disjoint) { // disjoint ! convex is empty
_halfspaces.Clear();
return;
}
if (iPosj == Halfspace.Position.Surrounds) {
_halfspaces.RemoveAt(i);
restart = true;
break;
} else if (iPosj == Halfspace.Position.Contained) {
_halfspaces.RemoveAt(j);
restart = true;
break;
}
} // for j
if(restart) break;
} // for i
}// while(redundancy)
// reset the sign of the convex
_sign = ((Halfspace) _halfspaces[0]).sign;
for(i = 1; i < _halfspaces.Count; i++) {
Halfspace hi = (Halfspace) _halfspaces[i];
switch(_sign){
case Halfspace.Sign.Negative:
if(hi.sign == Halfspace.Sign.Positive)
_sign = Halfspace.Sign.Mixed;
break;
case Halfspace.Sign.Positive:
if(hi.sign == Halfspace.Sign.Negative)
_sign = Halfspace.Sign.Mixed;
break;
case Halfspace.Sign.Zero:
_sign = hi.sign;
break;
case Halfspace.Sign.Mixed:
break;
}
}
if (_halfspaces.Count == 1) // for one constraint, it is itself the BC
_boundingCircle.copy((Halfspace) _halfspaces[0]);
else if (_sign == Halfspace.Sign.Positive)
_boundingCircle.copy((Halfspace) _halfspaces[0]);
}
