/// <summary>
/// <code>clip()</code> is the main method of the clipper This
/// is where the conversion from really begins.
/// </summary>
private static IPoly Clip(
OperationType op,
IPoly subj, IPoly clip,
Type polyType)
{
// Create an empty type
IPoly result = CreateNewPoly(polyType) ;
/* Test for trivial NULL result cases */
if( (subj.IsEmpty() && clip.IsEmpty()) ||
(subj.IsEmpty() && ((op == OperationType.GPC_INT) || (op == OperationType.GPC_DIFF))) ||
(clip.IsEmpty() && (op == OperationType.GPC_INT)) )
{
return result ;
}
/* Identify potentialy contributing contours */
if( ((op == OperationType.GPC_INT) || (op == OperationType.GPC_DIFF)) &&
!subj.IsEmpty() && !clip.IsEmpty() )
{
minimax_test(subj, clip, op);
}
/* Build LMT */
LmtTable lmt_table = new LmtTable();
ScanBeamTreeEntries sbte = new ScanBeamTreeEntries();
EdgeTable s_heap = null ;
EdgeTable c_heap = null ;
if (!subj.IsEmpty())
{
s_heap = build_lmt(lmt_table, sbte, subj, SUBJ, op);
}
#if DEBUG
// Show debugging information
Console.WriteLine("");
Console.WriteLine(" ------------ After build_lmt for subj ---------");
lmt_table.print();
#endif
if (!clip.IsEmpty())
{
c_heap = build_lmt(lmt_table, sbte, clip, CLIP, op);
}
#if DEBUG
// Debugging information
Console.WriteLine("");
Console.WriteLine(" ------------ After build_lmt for clip ---------");
lmt_table.print();
#endif
/* Return a NULL result if no contours contribute */
if (lmt_table.top_node == null)
{
return result;
}
/* Build scanbeam table from scanbeam tree */
double[] sbt = sbte.build_sbt();
int[] parity = new int[2] ;
parity[0] = LEFT ;
parity[1] = LEFT ;
/* Invert clip polygon for difference operation */
if (op == OperationType.GPC_DIFF)
{
parity[CLIP]= RIGHT;
}
#if DEBUG
print_sbt(sbt);
#endif
LmtNode local_min = lmt_table.top_node ;
TopPolygonNode out_poly = new TopPolygonNode(); // used to create resulting Poly
AetTree aet = new AetTree();
int scanbeam = 0 ;
/* Process each scanbeam */
while( scanbeam < sbt.Length )
{
/* Set yb and yt to the bottom and top of the scanbeam */
double yb = sbt[scanbeam++];
double yt = 0.0 ;
double dy = 0.0 ;
if( scanbeam < sbt.Length )
{
yt = sbt[scanbeam];
dy = yt - yb;
}
/* === SCANBEAM BOUNDARY PROCESSING ================================ */
/* If LMT node corresponding to yb exists */
if (local_min != null )
{
if (local_min.y == yb)
{
/* Add edges starting at this local minimum to the AET */
for( EdgeNode edge = local_min.first_bound; (edge != null) ; edge= edge.next_bound)
{
add_edge_to_aet( aet, edge );
}
local_min = local_min.next;
}
}
#if DEBUG
aet.print();
#endif
/* Set dummy previous x value */
double px = -Double.MaxValue ;
/* Create bundles within AET */
EdgeNode e0 = aet.top_node ;
EdgeNode e1 = aet.top_node ;
/* Set up bundle fields of first edge */
aet.top_node.bundle[ABOVE, aet.top_node.type ] = (aet.top_node.top.Y != yb) ? 1 : 0;
aet.top_node.bundle[ABOVE, ((aet.top_node.type==0) ? 1 : 0) ] = 0;
aet.top_node.bstate[ABOVE] = BundleState.UNBUNDLED;
for (EdgeNode next_edge= aet.top_node.next ; (next_edge != null); next_edge = next_edge.next)
{
int ne_type = next_edge.type ;
int ne_type_opp = ((next_edge.type==0) ? 1 : 0); //next edge type opposite
/* Set up bundle fields of next edge */
next_edge.bundle[ABOVE, ne_type ]= (next_edge.top.Y != yb) ? 1 : 0;
next_edge.bundle[ABOVE, ne_type_opp ] = 0 ;
next_edge.bstate[ABOVE] = BundleState.UNBUNDLED;
/* Bundle edges above the scanbeam boundary if they coincide */
if ( next_edge.bundle[ABOVE, ne_type] == 1 )
{
if (EQ(e0.xb, next_edge.xb) && EQ(e0.dx, next_edge.dx) && (e0.top.Y != yb))
{
next_edge.bundle[ABOVE, ne_type ] ^= e0.bundle[ABOVE, ne_type ];
next_edge.bundle[ABOVE, ne_type_opp ] = e0.bundle[ABOVE, ne_type_opp ];
next_edge.bstate[ABOVE] = BundleState.BUNDLE_HEAD;
e0.bundle[ABOVE, CLIP] = 0;
e0.bundle[ABOVE, SUBJ] = 0;
e0.bstate[ABOVE] = BundleState.BUNDLE_TAIL;
}
e0 = next_edge;
}
}
int[] horiz = new int[2] ;
horiz[CLIP]= HState.NH;
horiz[SUBJ]= HState.NH;
int[] exists = new int[2] ;
exists[CLIP] = 0 ;
exists[SUBJ] = 0 ;
PolygonNode cf = null ;
/* Process each edge at this scanbeam boundary */
for (EdgeNode edge= aet.top_node ; (edge != null); edge = edge.next )
{
exists[CLIP] = edge.bundle[ABOVE, CLIP] + (edge.bundle[BELOW, CLIP] << 1);
exists[SUBJ] = edge.bundle[ABOVE, SUBJ] + (edge.bundle[BELOW, SUBJ] << 1);
if( (exists[CLIP] != 0) || (exists[SUBJ] != 0) )
{
/* Set bundle side */
edge.bside[CLIP] = parity[CLIP];
edge.bside[SUBJ] = parity[SUBJ];
bool contributing = false ;
int br=0, bl=0, tr=0, tl=0 ;
/* Determine contributing status and quadrant occupancies */
if( (op == OperationType.GPC_DIFF) || (op == OperationType.GPC_INT) )
{
contributing= ((exists[CLIP]!=0) && ((parity[SUBJ]!=0) || (horiz[SUBJ]!=0))) ||
((exists[SUBJ]!=0) && ((parity[CLIP]!=0) || (horiz[CLIP]!=0))) ||
((exists[CLIP]!=0) && (exists[SUBJ]!=0) && (parity[CLIP] == parity[SUBJ]));
br = ((parity[CLIP]!=0) && (parity[SUBJ]!=0)) ? 1 : 0;
bl = ( ((parity[CLIP] ^ edge.bundle[ABOVE, CLIP])!=0) &&
((parity[SUBJ] ^ edge.bundle[ABOVE, SUBJ])!=0) ) ? 1 : 0;
tr = ( ((parity[CLIP] ^ ((horiz[CLIP]!=HState.NH)?1:0)) !=0) &&
((parity[SUBJ] ^ ((horiz[SUBJ]!=HState.NH)?1:0)) !=0) ) ? 1 : 0;
tl = (((parity[CLIP] ^ ((horiz[CLIP]!=HState.NH)?1:0) ^ edge.bundle[BELOW, CLIP])!=0) &&
((parity[SUBJ] ^ ((horiz[SUBJ]!=HState.NH)?1:0) ^ edge.bundle[BELOW, SUBJ])!=0))?1:0;
}
else if( op == OperationType.GPC_XOR )
{
contributing= (exists[CLIP]!=0) || (exists[SUBJ]!=0);
br= (parity[CLIP]) ^ (parity[SUBJ]);
bl= (parity[CLIP] ^ edge.bundle[ABOVE, CLIP]) ^ (parity[SUBJ] ^ edge.bundle[ABOVE, SUBJ]);
tr= (parity[CLIP] ^ ((horiz[CLIP]!=HState.NH)?1:0)) ^ (parity[SUBJ] ^ ((horiz[SUBJ]!=HState.NH)?1:0));
tl= (parity[CLIP] ^ ((horiz[CLIP]!=HState.NH)?1:0) ^ edge.bundle[BELOW, CLIP])
^ (parity[SUBJ] ^ ((horiz[SUBJ]!=HState.NH)?1:0) ^ edge.bundle[BELOW, SUBJ]);
}
else if( op == OperationType.GPC_UNION )
{
contributing= ((exists[CLIP]!=0) && (!(parity[SUBJ]!=0) || (horiz[SUBJ]!=0))) ||
((exists[SUBJ]!=0) && (!(parity[CLIP]!=0) || (horiz[CLIP]!=0))) ||
((exists[CLIP]!=0) && (exists[SUBJ]!=0) && (parity[CLIP] == parity[SUBJ]));
br= ((parity[CLIP]!=0) || (parity[SUBJ]!=0))?1:0;
bl= (((parity[CLIP] ^ edge.bundle[ABOVE, CLIP])!=0) || ((parity[SUBJ] ^ edge.bundle[ABOVE, SUBJ])!=0))?1:0;
tr= ( ((parity[CLIP] ^ ((horiz[CLIP]!=HState.NH)?1:0))!=0) ||
((parity[SUBJ] ^ ((horiz[SUBJ]!=HState.NH)?1:0))!=0) ) ?1:0;
tl= ( ((parity[CLIP] ^ ((horiz[CLIP]!=HState.NH)?1:0) ^ edge.bundle[BELOW, CLIP])!=0) ||
((parity[SUBJ] ^ ((horiz[SUBJ]!=HState.NH)?1:0) ^ edge.bundle[BELOW, SUBJ])!=0) ) ? 1:0;
}
else
{
throw new Exception("Unknown op");
}
/* Update parity */
parity[CLIP] ^= edge.bundle[ABOVE, CLIP];
parity[SUBJ] ^= edge.bundle[ABOVE, SUBJ];
/* Update horizontal state */
if (exists[CLIP]!=0)
{
horiz[CLIP] = HState.next_h_state[horiz[CLIP], ((exists[CLIP] - 1) << 1) + parity[CLIP]];
}
if( exists[SUBJ]!=0)
{
horiz[SUBJ] = HState.next_h_state[horiz[SUBJ], ((exists[SUBJ] - 1) << 1) + parity[SUBJ]];
}
if (contributing)
{
double xb = edge.xb;
VertexType vclass = (VertexType)
( tr + (tl << 1) + (br << 2) + (bl << 3));
switch (vclass)
{
case VertexType.EMN:
case VertexType.IMN:
edge.outp[ABOVE] = out_poly.add_local_min(xb, yb);
px = xb;
cf = edge.outp[ABOVE];
break;
case VertexType.ERI:
if (xb != px)
{
cf.add_right( xb, yb);
px= xb;
}
edge.outp[ABOVE]= cf;
cf= null;
break;
case VertexType.ELI:
edge.outp[BELOW].add_left( xb, yb);
px= xb;
cf= edge.outp[BELOW];
break;
case VertexType.EMX:
if (xb != px)
{
cf.add_left( xb, yb);
px= xb;
}
out_poly.merge_right(cf, edge.outp[BELOW]);
cf= null;
break;
case VertexType.ILI:
if (xb != px)
{
cf.add_left( xb, yb);
px= xb;
}
edge.outp[ABOVE]= cf;
cf= null;
break;
case VertexType.IRI:
edge.outp[BELOW].add_right( xb, yb );
px= xb;
cf= edge.outp[BELOW];
edge.outp[BELOW]= null;
break;
case VertexType.IMX:
if (xb != px)
{
cf.add_right( xb, yb );
px= xb;
}
out_poly.merge_left(cf, edge.outp[BELOW]);
cf= null;
edge.outp[BELOW]= null;
break;
case VertexType.IMM:
if (xb != px)
{
cf.add_right( xb, yb);
px= xb;
}
out_poly.merge_left(cf, edge.outp[BELOW]);
edge.outp[BELOW]= null;
edge.outp[ABOVE] = out_poly.add_local_min(xb, yb);
cf= edge.outp[ABOVE];
break;
case VertexType.EMM:
if (xb != px)
{
cf.add_left( xb, yb);
px= xb;
}
out_poly.merge_right(cf, edge.outp[BELOW]);
edge.outp[BELOW]= null;
edge.outp[ABOVE] = out_poly.add_local_min(xb, yb);
cf= edge.outp[ABOVE];
break;
case VertexType.LED:
if (edge.bot.Y == yb)
edge.outp[BELOW].add_left( xb, yb);
edge.outp[ABOVE]= edge.outp[BELOW];
px= xb;
break;
case VertexType.RED:
if (edge.bot.Y == yb)
edge.outp[BELOW].add_right( xb, yb );
edge.outp[ABOVE]= edge.outp[BELOW];
px= xb;
break;
default:
break;
} /* End of switch */
} /* End of contributing conditional */
} /* End of edge exists conditional */
#if DEBUG
out_poly.print();
#endif
} /* End of AET loop */
/* Delete terminating edges from the AET, otherwise compute xt */
for (EdgeNode edge = aet.top_node ; (edge != null); edge = edge.next)
{
if (edge.top.Y == yb)
{
EdgeNode prev_edge = edge.prev;
EdgeNode next_edge= edge.next;
if (prev_edge != null)
prev_edge.next = next_edge;
else
aet.top_node = next_edge;
if (next_edge != null )
next_edge.prev = prev_edge;
/* Copy bundle head state to the adjacent tail edge if required */
if ((edge.bstate[BELOW] == BundleState.BUNDLE_HEAD) && (prev_edge!=null))
{
if (prev_edge.bstate[BELOW] == BundleState.BUNDLE_TAIL)
{
prev_edge.outp[BELOW]= edge.outp[BELOW];
prev_edge.bstate[BELOW]= BundleState.UNBUNDLED;
if ( prev_edge.prev != null)
{
if (prev_edge.prev.bstate[BELOW] == BundleState.BUNDLE_TAIL)
{
prev_edge.bstate[BELOW] = BundleState.BUNDLE_HEAD;
}
}
}
}
}
else
{
if (edge.top.Y == yt)
edge.xt= edge.top.X;
else
edge.xt= edge.bot.X + edge.dx * (yt - edge.bot.Y);
}
}
if (scanbeam < sbte.sbt_entries )
{
/* === SCANBEAM INTERIOR PROCESSING ============================== */
/* Build intersection table for the current scanbeam */
ItNodeTable it_table = new ItNodeTable();
it_table.build_intersection_table(aet, dy);
/* Process each node in the intersection table */
for (ItNode intersect = it_table.top_node ; (intersect != null); intersect = intersect.next)
{
e0= intersect.ie[0];
e1= intersect.ie[1];
/* Only generate output for contributing intersections */
if ( ((e0.bundle[ABOVE, CLIP]!=0) || (e0.bundle[ABOVE, SUBJ]!=0)) &&
((e1.bundle[ABOVE, CLIP]!=0) || (e1.bundle[ABOVE, SUBJ]!=0)))
{
PolygonNode p = e0.outp[ABOVE];
PolygonNode q = e1.outp[ABOVE];
double ix = intersect.point.X;
double iy = intersect.point.Y + yb;
int in_clip = ( ( (e0.bundle[ABOVE, CLIP]!=0) && !(e0.bside[CLIP]!=0)) ||
( (e1.bundle[ABOVE, CLIP]!=0) && (e1.bside[CLIP]!=0)) ||
(!(e0.bundle[ABOVE, CLIP]!=0) && !(e1.bundle[ABOVE, CLIP]!=0) &&
(e0.bside[CLIP]!=0) && (e1.bside[CLIP]!=0) ) ) ? 1 : 0;
int in_subj = ( ( (e0.bundle[ABOVE, SUBJ]!=0) && !(e0.bside[SUBJ]!=0)) ||
( (e1.bundle[ABOVE, SUBJ]!=0) && (e1.bside[SUBJ]!=0)) ||
(!(e0.bundle[ABOVE, SUBJ]!=0) && !(e1.bundle[ABOVE, SUBJ]!=0) &&
(e0.bside[SUBJ]!=0) && (e1.bside[SUBJ]!=0) ) ) ? 1 : 0;
int tr=0, tl=0, br=0, bl=0 ;
/* Determine quadrant occupancies */
if( (op == OperationType.GPC_DIFF) || (op == OperationType.GPC_INT) )
{
tr= ((in_clip!=0) && (in_subj!=0)) ? 1 : 0;
tl= (((in_clip ^ e1.bundle[ABOVE, CLIP])!=0) && ((in_subj ^ e1.bundle[ABOVE, SUBJ])!=0))?1:0;
br= (((in_clip ^ e0.bundle[ABOVE, CLIP])!=0) && ((in_subj ^ e0.bundle[ABOVE, SUBJ])!=0))?1:0;
bl= (((in_clip ^ e1.bundle[ABOVE, CLIP] ^ e0.bundle[ABOVE, CLIP])!=0) &&
((in_subj ^ e1.bundle[ABOVE, SUBJ] ^ e0.bundle[ABOVE, SUBJ])!=0) ) ? 1:0;
}
else if( op == OperationType.GPC_XOR )
{
tr= (in_clip)^ (in_subj);
tl= (in_clip ^ e1.bundle[ABOVE, CLIP]) ^ (in_subj ^ e1.bundle[ABOVE, SUBJ]);
br= (in_clip ^ e0.bundle[ABOVE, CLIP]) ^ (in_subj ^ e0.bundle[ABOVE, SUBJ]);
bl= (in_clip ^ e1.bundle[ABOVE, CLIP] ^ e0.bundle[ABOVE, CLIP])
^ (in_subj ^ e1.bundle[ABOVE, SUBJ] ^ e0.bundle[ABOVE, SUBJ]);
}
else if( op == OperationType.GPC_UNION )
{
tr= ((in_clip!=0) || (in_subj!=0)) ? 1 : 0;
tl= (((in_clip ^ e1.bundle[ABOVE, CLIP])!=0) || ((in_subj ^ e1.bundle[ABOVE, SUBJ])!=0)) ? 1 : 0;
br= (((in_clip ^ e0.bundle[ABOVE, CLIP])!=0) || ((in_subj ^ e0.bundle[ABOVE, SUBJ])!=0)) ? 1 : 0;
bl= (((in_clip ^ e1.bundle[ABOVE, CLIP] ^ e0.bundle[ABOVE, CLIP])!=0) ||
((in_subj ^ e1.bundle[ABOVE, SUBJ] ^ e0.bundle[ABOVE, SUBJ])!=0)) ? 1 : 0;
}
else
{
throw new Exception("Unknown op type, "+op);
}
VertexType vclass = (VertexType)
( tr + (tl << 1) + (br << 2) + (bl << 3));
switch (vclass)
{
case VertexType.EMN:
e0.outp[ABOVE] = out_poly.add_local_min(ix, iy);
e1.outp[ABOVE] = e0.outp[ABOVE];
break;
case VertexType.ERI:
if (p != null)
{
p.add_right(ix, iy);
e1.outp[ABOVE]= p;
e0.outp[ABOVE]= null;
}
break;
case VertexType.ELI:
if (q != null)
{
q.add_left(ix, iy);
e0.outp[ABOVE]= q;
e1.outp[ABOVE]= null;
}
break;
case VertexType.EMX:
if ((p!=null) && (q!=null))
{
p.add_left( ix, iy);
out_poly.merge_right(p, q);
e0.outp[ABOVE]= null;
e1.outp[ABOVE]= null;
}
break;
case VertexType.IMN:
e0.outp[ABOVE] = out_poly.add_local_min(ix, iy);
e1.outp[ABOVE]= e0.outp[ABOVE];
break;
case VertexType.ILI:
if (p != null)
{
p.add_left(ix, iy);
e1.outp[ABOVE]= p;
e0.outp[ABOVE]= null;
}
break;
case VertexType.IRI:
if (q!=null)
{
q.add_right(ix, iy);
e0.outp[ABOVE]= q;
e1.outp[ABOVE]= null;
}
break;
case VertexType.IMX:
if ((p!=null) && (q!=null))
{
p.add_right(ix, iy);
out_poly.merge_left(p, q);
e0.outp[ABOVE]= null;
e1.outp[ABOVE]= null;
}
break;
case VertexType.IMM:
if ((p!=null) && (q!=null))
{
p.add_right(ix, iy);
out_poly.merge_left(p, q);
e0.outp[ABOVE] = out_poly.add_local_min(ix, iy);
e1.outp[ABOVE]= e0.outp[ABOVE];
}
break;
case VertexType.EMM:
if ((p!=null) && (q!=null))
{
p.add_left(ix, iy);
out_poly.merge_right(p, q);
e0.outp[ABOVE] = out_poly.add_local_min(ix, iy);
e1.outp[ABOVE] = e0.outp[ABOVE];
}
break;
default:
break;
} /* End of switch */
} /* End of contributing intersection conditional */
/* Swap bundle sides in response to edge crossing */
if (e0.bundle[ABOVE, CLIP]!=0)
e1.bside[CLIP] = (e1.bside[CLIP]==0)?1:0;
if (e1.bundle[ABOVE, CLIP]!=0)
e0.bside[CLIP]= (e0.bside[CLIP]==0)?1:0;
if (e0.bundle[ABOVE, SUBJ]!=0)
e1.bside[SUBJ]= (e1.bside[SUBJ]==0)?1:0;
if (e1.bundle[ABOVE, SUBJ]!=0)
e0.bside[SUBJ]= (e0.bside[SUBJ]==0)?1:0;
/* Swap e0 and e1 bundles in the AET */
EdgeNode prev_edge = e0.prev;
EdgeNode next_edge = e1.next;
if (next_edge != null)
{
next_edge.prev = e0;
}
if (e0.bstate[ABOVE] == BundleState.BUNDLE_HEAD)
{
bool search = true;
while (search)
{
prev_edge= prev_edge.prev;
if (prev_edge != null)
{
if (prev_edge.bstate[ABOVE] != BundleState.BUNDLE_TAIL)
{
search= false;
}
}
else
{
search= false;
}
}
}
if (prev_edge == null)
{
aet.top_node.prev = e1;
e1.next = aet.top_node;
aet.top_node = e0.next;
}
else
{
prev_edge.next.prev = e1;
e1.next = prev_edge.next;
prev_edge.next = e0.next;
}
e0.next.prev = prev_edge;
e1.next.prev = e1;
e0.next = next_edge;
#if DEBUG
out_poly.print();
#endif
} /* End of IT loop*/
/* Prepare for next scanbeam */
for ( EdgeNode edge = aet.top_node; (edge != null); edge = edge.next)
{
EdgeNode next_edge = edge.next;
EdgeNode succ_edge = edge.succ;
if ((edge.top.Y == yt) && (succ_edge!=null))
{
/* Replace AET edge by its successor */
succ_edge.outp[BELOW]= edge.outp[ABOVE];
succ_edge.bstate[BELOW]= edge.bstate[ABOVE];
succ_edge.bundle[BELOW, CLIP]= edge.bundle[ABOVE, CLIP];
succ_edge.bundle[BELOW, SUBJ]= edge.bundle[ABOVE, SUBJ];
EdgeNode prev_edge = edge.prev;
if ( prev_edge != null )
prev_edge.next = succ_edge;
else
aet.top_node = succ_edge;
if (next_edge != null)
next_edge.prev= succ_edge;
succ_edge.prev = prev_edge;
succ_edge.next = next_edge;
}
else
{
/* Update this edge */
edge.outp[BELOW]= edge.outp[ABOVE];
edge.bstate[BELOW]= edge.bstate[ABOVE];
edge.bundle[BELOW, CLIP]= edge.bundle[ABOVE, CLIP];
edge.bundle[BELOW, SUBJ]= edge.bundle[ABOVE, SUBJ];
edge.xb= edge.xt;
}
edge.outp[ABOVE]= null;
}
}
} /* === END OF SCANBEAM PROCESSING ================================== */
/* Generate result polygon from out_poly */
result = out_poly.getResult(polyType);
return result ;
}