void NaturalSpline::Get(DBL p, EXPRESS& v)
{
if (SplineEntries.size() == 1)
memcpy(&v, &SplineEntries.front().vec, sizeof(EXPRESS));
else
{
if (!Coeffs_Computed)
Precompute_Cubic_Coeffs(this);
/* Find which spline segment we're in. i is the control point at the end of the segment */
SplineEntryList::size_type i = findt(this, p);
for(int k=0; k<5; k++)
{
/* If outside the spline range, return the first or last point */
if(i == 0)
v[k] = SplineEntries.front().vec[k];
else if(i >= SplineEntries.size())
v[k] = SplineEntries.back().vec[k];
/* Else, normal case. cubic_interpolate can handle the case of not enough points */
else
v[k] = natural_interpolate(SplineEntries, i-1, k, p);
}
}
}
DBL Get_Spline_Val(SPLINE *sp, DBL p, EXPRESS v, int *Terms)
{
int i, k;
int last;
SPLINE_ENTRY * se;
*Terms = sp->Terms;
if(!sp->Coeffs_Computed)
{
switch(sp->Type)
{
case NATURAL_SPLINE:
Precompute_Cubic_Coeffs(sp);
break;
default:
break;
}
}
// check if the value is in the cache
if((sp->Cache_Point == p) && (sp->Cache_Type == sp->Type))
{
if(sp->Cache_Valid == true) // doing this here is more efficient as it is rarely false [trf]
{
Assign_Express(v, sp->Cache_Data);
return sp->Cache_Data[0];
}
}
// init some cache data
sp->Cache_Valid = false;
sp->Cache_Type = sp->Type;
sp->Cache_Point = p;
last = sp->Number_Of_Entries-1;
se = sp->SplineEntries;
if(last == 0)
{/* if only one entry then return this */
for(k=0; k<5; k++)
v[k] = se[0].vec[k];
return se[0].vec[0];
}
/* Find which spline segment we're in. i is the control point at the end of the segment */
i = findt(sp, p);
switch(sp->Type)
{
case LINEAR_SPLINE:
for(k=0; k<5; k++)
{
/* If outside spline range, return first or last point */
if(i == 0)
v[k] = se[0].vec[k];
else if(i > last)
v[k] = se[last].vec[k];
/* Else, normal case */
else
v[k] = linear_interpolate(se, i-1, k, p);
}
break;
case QUADRATIC_SPLINE:
for(k=0; k<5; k++)
{
/* If outside the spline range, return the first or last point */
if(i == 0)
v[k] = se[0].vec[k];
else if(i > last)
v[k] = se[last].vec[k];
/* If not enough points, reduce order */
else if(last == 1)
v[k] = linear_interpolate(se, i-1, k, p);
/* Normal case: between the second and last points */
else if(i > 1)
{
v[k] = quadratic_interpolate(se, i-1, k, p);
}
else /* Special case: between first and second points */
{
v[k] = quadratic_interpolate(se, i, k, p);
}
}
break;
case NATURAL_SPLINE:
for(k=0; k<5; k++)
{
/* If outside the spline range, return the first or last point */
if(i == 0)
v[k] = se[0].vec[k];
else if(i > last)
v[k] = se[last].vec[k];
/* Else, normal case. cubic_interpolate can handle the case of not enough points */
else
v[k] = natural_interpolate(se, i-1, k, p);
}
break;
case CATMULL_ROM_SPLINE:
for(k=0; k<5; k++)
{
/* If only two points, return their average */
if(last == 1)
v[k] = (se[0].vec[k] + se[1].vec[k])/2.0;
/* Catmull-Rom: If only three points, return the second one */
/* Catmull-Rom: Can't interpolate before second point or after next-to-last */
else if(i < 2)
v[k] = se[1].vec[k];
else if(i >= last)
v[k] = se[last-1].vec[k];
/* Else, normal case */
else
v[k] = catmull_rom_interpolate(se, i-1, k, p);
}
break;
default:
Error("Unknown spline type %d found.\n", sp->Type);
}
// put data in cache
Assign_Express(sp->Cache_Data, v);
sp->Cache_Valid = true;
return v[0];
}
