Speedup for flatcurves and NURBS curves getval() functions

rtengine/curves.cc

@@ -70,6 +70,18 @@ void Curve::AddPolygons ()
     poly_y.push_back(y3);
 }
 
+void Curve::fillDyByDx ()
+{
+    dyByDx.resize(poly_x.size() - 1);
+
+    for(unsigned int i = 0; i < poly_x.size() - 1; i++) {
+        double dx = poly_x[i + 1] - poly_x[i];
+        double dy = poly_y[i + 1] - poly_y[i];
+        dyByDx[i] = dy / dx;
+
+    }
+}
+
 void Curve::fillHash()
 {
     hash.resize(hashSize + 2);

rtengine/curves.h

@@ -336,6 +336,7 @@ protected:
     // end of variables used in Parametric curves only
     std::vector<double> poly_x;     // X points of the faceted curve
     std::vector<double> poly_y;     // Y points of the faceted curve
+    std::vector<double> dyByDx;
     std::vector<HashEntry> hash;
     unsigned short hashSize;        // hash table's size, between [10, 100, 1000]
 
@@ -369,6 +370,7 @@ protected:
     }
 
     void fillHash();
+    void fillDyByDx();
 
 public:
     Curve ();
@@ -406,7 +408,7 @@ public:
 class FlatCurve : public Curve
 {
 
-protected:
+private:
     FlatCurveType kind;
     double* leftTangent;
     double* rightTangent;

rtengine/diagonalcurves.cc

@@ -72,11 +72,15 @@ DiagonalCurve::DiagonalCurve (const std::vector<double>& p, int poly_pn)
 
             if(x[0] == 0.f && x[1] == 0.f)
                 // Avoid crash when first two points are at x = 0 (git Issue 2888)
+            {
                 x[1] = 0.01f;
+            }
 
             if(x[0] == 1.f && x[1] == 1.f)
                 // Avoid crash when first two points are at x = 1 (100 in gui) (git Issue 2923)
+            {
                 x[0] = 0.99f;
+            }
 
             if (!identity) {
                 if (kind == DCT_Spline && N > 2) {
@@ -260,6 +264,8 @@ void DiagonalCurve::NURBS_set ()
     // adding the final horizontal segment, always (see under)
     poly_x.push_back(3.0);      // 3.0 is a hack for optimization purpose of the getVal method (the last value has to be beyond the normal range)
     poly_y.push_back(y[N - 1]);
+
+    fillDyByDx();
 }
 
 double DiagonalCurve::getVal (double t) const
@@ -303,7 +309,7 @@ double DiagonalCurve::getVal (double t) const
         // do a binary search for the right interval:
         unsigned int k_lo = 0, k_hi = N - 1;
 
-        while (k_hi - k_lo > 1) {
+        while (k_hi > 1 + k_lo) {
             unsigned int k = (k_hi + k_lo) / 2;
 
             if (x[k] > t) {
@@ -347,7 +353,7 @@ double DiagonalCurve::getVal (double t) const
         k_hi = hash.at(i).higherValue;
 
         // do a binary search for the right interval :
-        while (k_hi - k_lo > 1) {
+        while (k_hi > 1 + k_lo) {
             unsigned int k = (k_hi + k_lo) / 2;
 
             if (poly_x[k] > t) {
@@ -357,13 +363,7 @@ double DiagonalCurve::getVal (double t) const
             }
         }
 
-        if (k_lo == k_hi) {
+        return poly_y[k_lo] + (t - poly_x[k_lo]) * dyByDx[k_lo];
-            k_hi = k_lo + 1;
-        }
-
-        double dx = poly_x[k_hi] - poly_x[k_lo];
-        double dy = poly_y[k_hi] - poly_y[k_lo];
-        return poly_y[k_lo] + (t - poly_x[k_lo]) * ( dy ) / dx;
         break;
     }
 

rtengine/flatcurves.cc

@@ -16,21 +16,14 @@
  *  You should have received a copy of the GNU General Public License
  *  along with RawTherapee.  If not, see <http://www.gnu.org/licenses/>.
  */
-#include <glib.h>
-#include <glib/gstdio.h>
 #include "curves.h"
 #include <cmath>
 #include <vector>
-#include "mytime.h"
-#include <cstring>
-
-#include <gtkmm.h>
-#include <fstream>
 
 namespace rtengine
 {
 
-FlatCurve::FlatCurve (const std::vector<double>& p, bool isPeriodic, int poly_pn) : kind(FCT_Empty), leftTangent(NULL), rightTangent(NULL), identityValue(0.5), periodic(isPeriodic)
+FlatCurve::FlatCurve (const std::vector<double>& p, bool isPeriodic, int poly_pn) : kind(FCT_Empty), leftTangent(nullptr), rightTangent(nullptr), identityValue(0.5), periodic(isPeriodic)
 {
 
     ppn = poly_pn > 65500 ? 65500 : poly_pn;
@@ -341,17 +334,7 @@ void FlatCurve::CtrlPoints_set ()
     poly_x.push_back(3.0);      // 3.0 is a hack for optimization purpose of the getVal method (the last value has to be beyond the normal range)
     poly_y.push_back(sc_y[j - 1]);
 
-    /*
+    fillDyByDx();
-    // Checking the values
-    Glib::ustring fname = "Curve.xyz"; // TopSolid'Design "plot" file format
-    std::ofstream f (fname.c_str());
-    f << "$" << std::endl;;
-    for (unsigned int iter = 0; iter < poly_x.size(); iter++) {
-        f << poly_x[iter] << ", " << poly_y[iter] << ", 0." << std::endl;;
-    }
-    f << "$" << std::endl;;
-    f.close ();
-    */
 }
 
 double FlatCurve::getVal (double t) const
@@ -367,10 +350,10 @@ double FlatCurve::getVal (double t) const
         }
 
         // do a binary search for the right interval:
-        int k_lo = 0, k_hi = poly_x.size() - 1;
+        unsigned int k_lo = 0, k_hi = poly_x.size() - 1;
 
-        while (k_hi - k_lo > 1) {
+        while (k_hi > 1 + k_lo) {
-            int k = (k_hi + k_lo) / 2;
+            unsigned int k = (k_hi + k_lo) / 2;
 
             if (poly_x[k] > t) {
                 k_hi = k;
@@ -379,9 +362,7 @@ double FlatCurve::getVal (double t) const
             }
         }
 
-        double dx = poly_x[k_hi] - poly_x[k_lo];
+        return poly_y[k_lo] + (t - poly_x[k_lo]) * dyByDx[k_lo];
-        double dy = poly_y[k_hi] - poly_y[k_lo];
-        return poly_y[k_lo] + (t - poly_x[k_lo]) * dy / dx;
         break;
     }