Modified Files:

[simgear.git] / simgear / math / interpolater.cxx

diff --git a/simgear/math/interpolater.cxx b/simgear/math/interpolater.cxx
index 206e99a723e5e5c839782e820dd6060e87eb5657..28fd23eee2750032108c876183a504a9bc45e824 100644 (file)
--- a/simgear/math/interpolater.cxx
+++ b/simgear/math/interpolater.cxx
@@ -4,7 +4,7 @@
 //
 // Written by Curtis Olson, started April 1998.
 //
-// Copyright (C) 1998  Curtis L. Olson  - curt@me.umn.edu
+// Copyright (C) 1998  Curtis L. Olson  - http://www.flightgear.org/~curt
 //
 // This library is free software; you can redistribute it and/or
 // modify it under the terms of the GNU Library General Public
@@ -16,10 +16,9 @@
 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 // Library General Public License for more details.
 //
-// You should have received a copy of the GNU Library General Public
-// License along with this library; if not, write to the
-// Free Software Foundation, Inc., 59 Temple Place - Suite 330,
-// Boston, MA  02111-1307, USA.
+// 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., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
 //
 // $Id$
 
@@ -30,76 +29,90 @@
 
 #include STL_STRING
 
-// depricated - #include <simgear/sg_zlib.h>
 #include <simgear/debug/logstream.hxx>
-#include <simgear/misc/fgstream.hxx>
+#include <simgear/misc/sgstream.hxx>
 
 #include "interpolater.hxx"
 
 SG_USING_STD(string);
 
+// Constructor -- starts with an empty table.
+SGInterpTable::SGInterpTable()
+    : size(0)
+{
+}
+
 
 // Constructor -- loads the interpolation table from the specified
 // file
-SGInterpTable::SGInterpTable( const string& file ) {
+SGInterpTable::SGInterpTable( const string& file ) 
+  : size(0)
+{
     SG_LOG( SG_MATH, SG_INFO, "Initializing Interpolator for " << file );
 
-    fg_gzifstream in( file );
+    sg_gzifstream in( file );
     if ( !in.is_open() ) {
         SG_LOG( SG_GENERAL, SG_ALERT, "Cannot open file: " << file );
        exit(-1);
     }
 
-    size = 0;
     in >> skipcomment;
     while ( in ) {
-       if ( size < MAX_TABLE_SIZE ) {
-           in >> table[size][0] >> table[size][1];
-           in >> skipws;
-           size++;
-       } else {
-            SG_LOG( SG_MATH, SG_ALERT,
-                   "fgInterpolateInit(): Exceed max table size = "
-                   << MAX_TABLE_SIZE );
-           exit(-1);
-       }
+      double ind, dep;
+      in >> ind >> dep;
+      in >> skipws;
+      table.push_back(Entry(ind, dep));
+      size++;
     }
 }
 
 
+// Add an entry to the table.
+void SGInterpTable::addEntry (double ind, double dep)
+{
+  table.push_back(Entry(ind,dep));
+  size++;
+}
+
+
 // Given an x value, linearly interpolate the y value from the table
-double SGInterpTable::interpolate(double x) {
+double SGInterpTable::interpolate(double x) const
+{
     int i;
     double y;
 
+    if (size == 0.0) {
+      return 0.0;
+    }
+
     i = 0;
 
-    while ( (x > table[i][0]) && (i < size) ) {
-       // cout << "  i = " << i << " table[i][0] = " << table[i][0] << endl;
+    while ( (i < size) && (x > table[i].ind) ) {
+       // cout << "  i = " << i << " table[i].ind = " << table[i].ind << endl;
        // cout << "  size = " << size << endl;
        i++;
     }
 
     // printf ("i = %d ", i);
 
-    if ( (i == 0) && (x < table[0][0]) ) {
+    if ( i <= 0 ) {
        SG_LOG( SG_MATH, SG_DEBUG, 
                "interpolate(): lookup error, x to small = " << x );
-       return table[0][1];
+       return table[0].dep;
     }
 
-    // cout << " table[size-1][0] = " << table[size-1][0] << endl;
-    if ( x > table[size-1][0] ) {
+    // cout << " table[size-1].ind = " << table[size-1].ind << endl;
+    if ( i >= size ) {
        SG_LOG( SG_MATH, SG_DEBUG, 
                "interpolate(): lookup error, x to big = " << x );
-       return table[size-1][1];
+       return table[size-1].dep;
     }
 
     // y = y1 + (y0 - y1)(x - x1) / (x0 - x1)
-    y = table[i][1] + 
-       ( (table[i-1][1] - table[i][1]) * 
-         (x - table[i][0]) ) /
-       (table[i-1][0] - table[i][0]);
+    y = table[i].dep + 
+       ( (table[i-1].dep - table[i].dep) * 
+         (x - table[i].ind) ) /
+       (table[i-1].ind - table[i].ind);
 
     return(y);
 }