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Initial revision.

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curt 2000-05-08 17:17:43 +00:00
parent 16ef7b7bbc
commit 665f663043
2 changed files with 158 additions and 0 deletions

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// genstrips.cxx -- Optimize a collection of individual triangles into
// strips.
//
// Written by Curtis Olson, started May 2000.
//
// Copyright (C) 2000 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.
//
// $Id$
#include <simgear/compiler.h>
#include "genstrips.hxx"
// make sure the list is expanded at least to hold "n" and then push
// "i" onto the back of the "n" list.
static void add_and_expand( opt_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);
}
// generate a set of tri-strips from a random collection of triangles.
// Note, the triangle verticies are integer indices into a vertex list
// and not actual vertex data.
opt_list tgGenStrips( const triele_list tris ) {
triele_list remaining = tris;
while ( remaining.size() ) {
// traverse the triangle list and for each node, build a list of
// triangles that attach to it.
// cout << "building by_node list" << endl;
opt_list by_node;
by_node.clear();
for ( int i = 0; i < (int)remaining.size(); ++i ) {
int n1 = remaining[i].get_n1();
int n2 = remaining[i].get_n2();
int n3 = remaining[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 least connected triangle (this is a popular
// heuristic for starting finding a good set of triangle
// strips.)
int min_size = 32768;
int min_tri = -1;
for ( int i = 0; i < (int)remaining.size(); ++i ) {
int n1 = remaining[i].get_n1();
int n2 = remaining[i].get_n2();
int n3 = remaining[i].get_n3();
int metric = 0;
metric += by_node[n1].size();
metric += by_node[n2].size();
metric += by_node[n3].size();
if ( metric < min_size ) {
min_size = metric;
min_tri = i;
}
}
}
}

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// genstrips.hxx -- Optimize a collection of individual triangles into
// strips.
//
// Written by Curtis Olson, started May 2000.
//
// Copyright (C) 2000 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.
//
// $Id$
#ifndef _GENSTRIPS_HXX
#define _GENSTRIPS_HXX
#ifndef __cplusplus
# error This library requires C++
#endif
#include <simgear/compiler.h>
#include <vector>
#include <simgear/math/fg_types.hxx>
#include <Triangulate/trieles.hxx>
FG_USING_STD(vector);
typedef vector < int_list > opt_list;
typedef opt_list::iterator opt_list_iterator;
typedef opt_list::const_iterator const_opt_list_iterator;
// generate a set of tri-strips from a random collection of triangles.
// Note, the triangle verticies are integer indices into a vertex list
// and not actual vertex data.
opt_list tgGenStrips( const triele_list tris );
#endif // _GENSTRIPS_HXX