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STL-ified the interpolation table so it is not size limited.

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This commit is contained in:
curt
2001-05-15 21:07:41 +00:00
parent 2afd1c8663
commit e145f903de
2 changed files with 69 additions and 27 deletions
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62
simgear/math/interpolater.cxx
View File

@@ -38,10 +38,18 @@
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 );
sg_gzifstream in( file );
@@ -50,56 +58,62 @@ SGInterpTable::SGInterpTable( const string& 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) && (x < table[0].ind) ) {
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 ( x > table[size-1].ind ) {
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);
}

34
simgear/math/interpolater.hxx
View File

@@ -36,10 +36,12 @@
#include <simgear/compiler.h>
#include <vector>
SG_USING_STD(vector);
#include STL_STRING
SG_USING_STD(string);
#define MAX_TABLE_SIZE 32
/**
* A class that provids a simple linear 2d interpolation lookup table.
@@ -48,23 +50,49 @@ SG_USING_STD(string);
* variable can be anything.
*/
class SGInterpTable {
struct Entry
{
Entry ()
: ind(0.0L), dep(0.0L) {}
Entry (double independent, double dependent)
: ind(independent), dep(dependent) {}
double ind;
double dep;
};
int size;
double table[MAX_TABLE_SIZE][2];
vector<Entry> table;
public:
/**
* Constructor. Creates a new, empty table.
*/
SGInterpTable();
/**
* Constructor. Loads the interpolation table from the specified file.
* @param file name of interpolation file
*/
SGInterpTable( const string& file );
/**
* Add an entry to the table, extending the table's length.
*
* @param ind The independent variable.
* @param dep The dependent variable.
*/
void addEntry (double ind, double dep);
/**
* Given an x value, linearly interpolate the y value from the table.
* @param x independent variable
* @return interpolated dependent variable
*/
double interpolate(double x);
double interpolate(double x) const;
/** Destructor */
~SGInterpTable();