--- /dev/null
+// genfans.cxx -- Combine individual triangles into more optimal fans.
+//
+// Written by Curtis Olson, started March 1999.
+//
+// Copyright (C) 1999 Curtis L. Olson - curt@flightgear.org
+//
+// This program is free software; you can redistribute it and/or
+// modify it under the terms of the GNU General Public License as
+// published by the Free Software Foundation; either version 2 of the
+// License, or (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful, but
+// WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+// General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with this program; if not, write to the Free Software
+// Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+//
+// $Id$
+// (Log is kept at end of this file)
+
+
+#include "genfans.hxx"
+
+
+// make sure the list is expanded at least to hold "n" and then push
+// "i" onto the back of the "n" list.
+void FGGenFans::add_and_expand( reverse_list& by_node, int n, int i ) {
+ int_list empty;
+
+ int size = (int)by_node.size();
+ if ( size > n ) {
+ // ok
+ } else {
+ // cout << "capacity = " << by_node.capacity() << endl;
+ // cout << "size = " << size << " n = " << n
+ // << " need to push = " << n - size + 1 << endl;
+ for ( int i = 0; i < n - size + 1; ++i ) {
+ by_node.push_back(empty);
+ }
+ }
+
+ by_node[n].push_back(i);
+}
+
+
+// given an input triangle, shuffle nodes so that "center" is the
+// first node, but maintain winding order.
+static FGTriEle canonify( const FGTriEle& t, int center ) {
+ if ( t.get_n1() == center ) {
+ // already ok
+ return t;
+ } else if ( t.get_n2() == center ) {
+ return FGTriEle( t.get_n2(), t.get_n3(), t.get_n1(), 0.0 );
+ } else if ( t.get_n3() == center ) {
+ return FGTriEle( t.get_n3(), t.get_n1(), t.get_n2(), 0.0 );
+ } else {
+ cout << "ERROR, index doesn't refer to this triangle!!!" << endl;
+ exit(-1);
+ }
+}
+
+static int_list make_best_fan( const triele_list& master_tris,
+ const int center, const int_list& local_tris )
+{
+ int_list best_result;
+
+ // try starting with local triangle to find the best fan arrangement
+ for ( int start = 0; start < (int)local_tris.size(); ++start ) {
+ cout << "trying with first triangle = " << local_tris[start] << endl;
+
+ int_list tmp_result;
+ tmp_result.clear();
+
+ FGTriEle current_tri;
+ FGTriEle test;
+ current_tri = canonify( master_tris[local_tris[start]], center );
+ tmp_result.push_back( local_tris[start] );
+
+ // follow the ring
+ int next = -1;
+ bool matches = true;
+ while ( (next != start) && matches ) {
+ // find next triangle in ring
+ matches = false;
+ for ( int i = 0; i < (int)local_tris.size(); ++i ) {
+ test = canonify( master_tris[local_tris[i]], center );
+ if ( current_tri.get_n3() == test.get_n2() ) {
+ if ( i != start ) {
+ cout << " next triangle = " << local_tris[i] << endl;
+ current_tri = test;
+ tmp_result.push_back( local_tris[i] );
+ matches = true;
+ next = i;
+ break;
+ }
+ }
+ }
+ }
+
+ if ( tmp_result.size() == local_tris.size() ) {
+ // we found a complete usage, no need to go on
+ cout << "we found a complete usage, no need to go on" << endl;
+ best_result = tmp_result;
+ break;
+ } else if ( tmp_result.size() > best_result.size() ) {
+ // we found a better way to fan
+ cout << "we found a better fan arrangement" << endl;
+ best_result = tmp_result;
+ }
+ }
+
+ return best_result;
+}
+
+
+static bool in_fan(int index, const int_list& fan ) {
+ const_int_list_iterator current = fan.begin();
+ const_int_list_iterator last = fan.end();
+
+ for ( ; current != last; ++current ) {
+ if ( index == *current ) {
+ return true;
+ }
+ }
+
+ return false;
+}
+
+
+// recursive build fans from triangle list
+fan_list FGGenFans::greedy_build( triele_list tris ) {
+ cout << "starting greedy build of fans" << endl;
+
+ while ( ! tris.empty() ) {
+ reverse_list by_node;
+ by_node.clear();
+
+ // traverse the triangle list and for each node, build a list of
+ // triangles that attach to it.
+
+ for ( int i = 0; i < (int)tris.size(); ++i ) {
+ int n1 = tris[i].get_n1();
+ int n2 = tris[i].get_n2();
+ int n3 = tris[i].get_n3();
+
+ add_and_expand( by_node, n1, i );
+ add_and_expand( by_node, n2, i );
+ add_and_expand( by_node, n3, i );
+ }
+
+ // find the node in the tris list that attaches to the most
+ // triangles
+
+ int_list biggest_group;
+ reverse_list_iterator r_current = by_node.begin();
+ reverse_list_iterator r_last = by_node.end();
+ int index = 0;
+ int counter = 0;
+ for ( ; r_current != r_last; ++r_current ) {
+ if ( r_current->size() > biggest_group.size() ) {
+ biggest_group = *r_current;
+ index = counter;
+ }
+ ++counter;
+ }
+ cout << "master triangle pool = " << tris.size() << endl;
+ cout << "biggest_group = " << biggest_group.size() << endl;
+ cout << "center node = " << index << endl;
+
+ // make the best fan we can out of this group
+ int_list best_fan = make_best_fan( tris, index, biggest_group );
+
+ // add this fan to the fan list
+ fans.push_back( best_fan );
+
+ // delete the triangles in best_fan out of tris and repeat
+ triele_list_iterator t_current = tris.begin();
+ triele_list_iterator t_last = tris.end();
+ counter = 0;
+ for ( ; t_current != t_last; ++t_current ) {
+ if ( in_fan(counter, best_fan) ) {
+ // cout << "erasing " << counter << " from master tri pool"
+ // << endl;
+ tris.erase( t_current );
+ }
+ ++counter;
+ }
+ }
+
+ cout << "end of greedy build of fans" << endl;
+ cout << "average fan size = " << ave_size() << endl;
+
+ return fans;
+}
+
+
+// report average fan size
+double FGGenFans::ave_size() {
+ double sum;
+
+ fan_list_iterator current = fans.begin();
+ fan_list_iterator last = fans.end();
+ for ( ; current != last; ++current ) {
+ sum += current->size();
+ }
+
+ return sum / (double)fans.size();
+}
+
+
+// $Log$
+// Revision 1.1 1999/03/29 13:08:35 curt
+// Initial revision.
+//
--- /dev/null
+// genfans.hxx -- Combine individual triangles into more optimal fans.
+//
+// Written by Curtis Olson, started March 1999.
+//
+// Copyright (C) 1999 Curtis L. Olson - curt@flightgear.org
+//
+// This program is free software; you can redistribute it and/or
+// modify it under the terms of the GNU General Public License as
+// published by the Free Software Foundation; either version 2 of the
+// License, or (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful, but
+// WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+// General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with this program; if not, write to the Free Software
+// Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+//
+// $Id$
+// (Log is kept at end of this file)
+
+
+#ifndef _GENFANS_HXX
+#define _GENFANS_HXX
+
+
+#ifndef __cplusplus
+# error This library requires C++
+#endif
+
+
+#include <Include/compiler.h>
+
+#include <vector>
+
+#include <Main/construct_types.hxx>
+#include <Triangulate/trieles.hxx>
+
+FG_USING_STD(vector);
+
+
+typedef vector < int_list > fan_list;
+typedef fan_list::iterator fan_list_iterator;
+typedef fan_list::const_iterator const_fan_list_iterator;
+
+typedef vector < int_list > reverse_list;
+typedef reverse_list::iterator reverse_list_iterator;
+typedef reverse_list::const_iterator const_reverse_list_iterator;
+
+
+
+class FGGenFans {
+
+private:
+
+ fan_list fans;
+
+ // make sure the list is expanded at least to hold "n" and then
+ // push "i" onto the back of the "n" list.
+ void add_and_expand( reverse_list& by_node, int n, int i );
+
+public:
+
+ // Constructor && Destructor
+ inline FGGenFans() { }
+ inline ~FGGenFans() { }
+
+ // recursive build fans from triangle list
+ // fan_list greedy_build( triele_list tris );
+ fan_list greedy_build( triele_list tris );
+
+ // report average fan size
+ double ave_size();
+};
+
+
+#endif // _GENFANS_HXX
+
+
+// $Log$
+// Revision 1.1 1999/03/29 13:08:35 curt
+// Initial revision.
+//
projects / flightgear.git / commitdiff