[geos-commits] [SCM] GEOS branch main updated. b8222e43d37e560850d523ac7321705a0b84262d

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- Log -----------------------------------------------------------------
commit b8222e43d37e560850d523ac7321705a0b84262d
Merge: c679bff3e 50f3c5f56
Author: Paul Ramsey <pramsey at cleverelephant.ca>
Date:   Mon Feb 3 12:43:50 2025 -0800

    Merge branch 'tinko92-orientation-tighter-error-bound'


commit 50f3c5f56b7c463968d1e35870673b2970bc4afc
Author: Paul Ramsey <pramsey at cleverelephant.ca>
Date:   Mon Feb 3 12:41:36 2025 -0800

    Update comment on orientationIndexFilter()

diff --git a/include/geos/algorithm/CGAlgorithmsDD.h b/include/geos/algorithm/CGAlgorithmsDD.h
index 44e64c0cc..7641e5f46 100644
--- a/include/geos/algorithm/CGAlgorithmsDD.h
+++ b/include/geos/algorithm/CGAlgorithmsDD.h
@@ -77,15 +77,22 @@ public:
      * A filter for computing the orientation index of three coordinates.
      *
      * If the orientation can be computed safely using standard DP arithmetic,
-     * this routine returns the orientation index. Otherwise, a value `i > 1` is
-     * returned. In this case the orientation index must be computed using some
-     * other more robust method.
+     * this routine returns the orientation index.
      *
      * The filter is fast to compute, so can be used to avoid the use of slower
      * robust methods except when they are really needed, thus providing better
      * average performance.
      *
-     * Uses an approach due to Jonathan Shewchuk, which is in the public domain.
+     * Jonathan Shewchuk
+     * Robust Adaptive Floating-Point Geometric Predicates
+     * Proceedings of the Twelfth Annual Symposium on Computational Geometry, ACM,
+     * May 1996
+     *
+     * Ozaki, K., Bünger, F., Ogita, T. et al.
+     * Simple floating-point filters for the two-dimensional orientation problem.
+     * Bit Numer Math 56, 729–749 (2016).
+     * https://doi.org/10.1007/s10543-015-0574-9
+     *
      */
     static inline int orientationIndexFilter(
         double pax, double pay,
@@ -95,7 +102,7 @@ public:
         double const detleft = (pax - pcx) * (pby - pcy);
         double const detright = (pay - pcy) * (pbx - pcx);
         double const det = detleft - detright;
-        // Coefficient due to https://doi.org/10.1007/s10543-015-0574-9
+        // Coefficient as per Ozaki et al
         double const error = std::abs(detleft + detright)
                              * 3.3306690621773724e-16;
         if (std::abs(det) >= error)

commit c525cb41e12a6490085f7493ecd87dd59099a909
Merge: c679bff3e 8e4e03ee3
Author: Paul Ramsey <pramsey at cleverelephant.ca>
Date:   Mon Feb 3 12:36:50 2025 -0800

    Merge branch 'orientation-tighter-error-bound' of github.com:tinko92/geos into tinko92-orientation-tighter-error-bound


commit 8e4e03ee3b871181b801a38d8aedd36b5d8899f0
Author: tinko92 <mail at tinkobartels.de>
Date:   Sun Oct 27 09:16:25 2024 +0800

    Use Ozaki et al.'s error bound and single-branch evaluation in orientation index filter.

diff --git a/include/geos/algorithm/CGAlgorithmsDD.h b/include/geos/algorithm/CGAlgorithmsDD.h
index ef251c3ee..a3ca957ce 100644
--- a/include/geos/algorithm/CGAlgorithmsDD.h
+++ b/include/geos/algorithm/CGAlgorithmsDD.h
@@ -20,6 +20,7 @@
 
 #include <geos/export.h>
 #include <geos/math/DD.h>
+#include <cmath>
 
 // Forward declarations
 namespace geos {
@@ -92,41 +93,14 @@ public:
         double pbx, double pby,
         double pcx, double pcy)
     {
-        /**
-         * A value which is safely greater than the relative round-off
-         * error in double-precision numbers
-         */
-        double constexpr DP_SAFE_EPSILON =  1e-15;
-
-        double detsum;
         double const detleft = (pax - pcx) * (pby - pcy);
         double const detright = (pay - pcy) * (pbx - pcx);
         double const det = detleft - detright;
-
-        if(detleft > 0.0) {
-            if(detright <= 0.0) {
-                return orientation(det);
-            }
-            else {
-                detsum = detleft + detright;
-            }
-        }
-        else if(detleft < 0.0) {
-            if(detright >= 0.0) {
-                return orientation(det);
-            }
-            else {
-                detsum = -detleft - detright;
-            }
-        }
-        else {
-            return orientation(det);
-        }
-
-        double const errbound = DP_SAFE_EPSILON * detsum;
-        if((det >= errbound) || (-det >= errbound)) {
-            return orientation(det);
-        }
+        // Coefficient due to https://doi.org/10.1007/s10543-015-0574-9
+        double const error = std::abs(detleft + detright)
+                             * 3.3306690621773724e-16;
+        if (std::abs(det) >= error)
+            return (det > 0) - (det < 0);
         return CGAlgorithmsDD::FAILURE;
     };
 
@@ -188,6 +162,3 @@ protected:
 
 } // namespace geos::algorithm
 } // namespace geos
-
-
-

-----------------------------------------------------------------------

Summary of changes:
 include/geos/algorithm/CGAlgorithmsDD.h | 56 ++++++++++-----------------------
 1 file changed, 17 insertions(+), 39 deletions(-)


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