From 848f54d4a77f38a234ec2facdb5eefd1442bc1b4 Mon Sep 17 00:00:00 2001
From: Klaus Basan <klaus.basan@klausbasan.de>
Date: Thu, 16 May 2019 14:43:11 +0200
Subject: [PATCH] Ref T668, clamp time fraction [0,1]

---
 src/blackmisc/simulation/interpolatorfunctions.h |  6 ++++++
 src/blackmisc/simulation/interpolatorlinear.cpp  | 15 ++++++++-------
 src/blackmisc/simulation/interpolatorpbh.cpp     |  5 ++++-
 3 files changed, 18 insertions(+), 8 deletions(-)

diff --git a/src/blackmisc/simulation/interpolatorfunctions.h b/src/blackmisc/simulation/interpolatorfunctions.h
index fc5f13504..df7a5c5cc 100644
--- a/src/blackmisc/simulation/interpolatorfunctions.h
+++ b/src/blackmisc/simulation/interpolatorfunctions.h
@@ -21,6 +21,12 @@ namespace BlackMisc
             return timeFraction >= 0.0 && timeFraction <= 1.0;
         }
 
+        //! Valid time fraction [0,1], this allows minor overshooting
+        inline bool isAcceptableTimeFraction(double timeFraction)
+        {
+            return timeFraction >= 0.0 && timeFraction <= 1.01;
+        }
+
         //! Clamp time fraction [0,1]
         inline double clampValidTimeFraction(double timeFraction)
         {
diff --git a/src/blackmisc/simulation/interpolatorlinear.cpp b/src/blackmisc/simulation/interpolatorlinear.cpp
index ec0759311..ec2708e9c 100644
--- a/src/blackmisc/simulation/interpolatorlinear.cpp
+++ b/src/blackmisc/simulation/interpolatorlinear.cpp
@@ -66,14 +66,15 @@ namespace BlackMisc
             {
                 BLACK_VERIFY_X(CAircraftSituation::isValidVector(oldVec), Q_FUNC_INFO, "Invalid old vector");
                 BLACK_VERIFY_X(CAircraftSituation::isValidVector(newVec), Q_FUNC_INFO, "Invalid new vector");
-                BLACK_VERIFY_X(isValidTimeFraction(m_simulationTimeFraction), Q_FUNC_INFO, "Invalid fraction");
+                BLACK_VERIFY_X(isAcceptableTimeFraction(m_simulationTimeFraction), Q_FUNC_INFO, "Invalid fraction");
             }
 
             // Interpolate position: pos = (posB - posA) * t + posA
             CCoordinateGeodetic newPosition;
-            newPosition.setNormalVector((newVec[0] - oldVec[0]) * m_simulationTimeFraction + oldVec[0],
-                                        (newVec[1] - oldVec[1]) * m_simulationTimeFraction + oldVec[1],
-                                        (newVec[2] - oldVec[2]) * m_simulationTimeFraction + oldVec[2]);
+            const double tf = clampValidTimeFraction(m_simulationTimeFraction);
+            newPosition.setNormalVector((newVec[0] - oldVec[0]) * tf + oldVec[0],
+                                        (newVec[1] - oldVec[1]) * tf + oldVec[1],
+                                        (newVec[2] - oldVec[2]) * tf + oldVec[2]);
 
             if (CBuildConfig::isLocalDeveloperDebugBuild())
             {
@@ -86,7 +87,7 @@ namespace BlackMisc
             const CAltitude newAlt(m_newSituation.getCorrectedAltitude());
             Q_ASSERT_X(oldAlt.getReferenceDatum() == CAltitude::MeanSeaLevel && oldAlt.getReferenceDatum() == newAlt.getReferenceDatum(), Q_FUNC_INFO, "mismatch in reference"); // otherwise no calculation is possible
             const CAltitude altitude((newAlt - oldAlt)
-                                     * m_simulationTimeFraction
+                                     * tf
                                      + oldAlt,
                                      oldAlt.getReferenceDatum());
 
@@ -102,8 +103,8 @@ namespace BlackMisc
                 do
                 {
                     if (CAircraftSituation::isGfEqualAirborne(oldGroundFactor, newGroundFactor)) { newSituation.setOnGround(false); break; }
-                    if (CAircraftSituation::isGfEqualOnGround(oldGroundFactor, newGroundFactor)) { newSituation.setOnGround(true); break; }
-                    const double groundFactor = (newGroundFactor - oldGroundFactor) * m_simulationTimeFraction + oldGroundFactor;
+                    if (CAircraftSituation::isGfEqualOnGround(oldGroundFactor, newGroundFactor)) { newSituation.setOnGround(true);  break; }
+                    const double groundFactor = (newGroundFactor - oldGroundFactor) * tf + oldGroundFactor;
                     newSituation.setOnGroundFactor(groundFactor);
                     newSituation.setOnGroundFromGroundFactorFromInterpolation(groundInterpolationFactor());
                 }
diff --git a/src/blackmisc/simulation/interpolatorpbh.cpp b/src/blackmisc/simulation/interpolatorpbh.cpp
index 901506bbe..00bb8551e 100644
--- a/src/blackmisc/simulation/interpolatorpbh.cpp
+++ b/src/blackmisc/simulation/interpolatorpbh.cpp
@@ -32,9 +32,12 @@ namespace BlackMisc
 
             if (CBuildConfig::isLocalDeveloperDebugBuild())
             {
-                BLACK_VERIFY_X(isValidTimeFraction(timeFraction0to1), Q_FUNC_INFO, "0..1 fraction needed");
+                BLACK_VERIFY_X(isAcceptableTimeFraction(timeFraction0to1), Q_FUNC_INFO, "0..1 fraction needed");
             }
 
+            //! make sure to not end up we extrapolation
+            if (timeFraction0to1 >= 1.0) { return begin + CAngle(deltaDeg, CAngleUnit::deg()); }
+            if (timeFraction0to1 <= 0.0) { return begin; }
             return begin + CAngle(timeFraction0to1 * deltaDeg, CAngleUnit::deg());
         }