logic/pipeline: smoothen transition for reltrans not aiming

Requested by: HOPPING_PONY on the Russian IL-2 Sturmovik forum.

2 files changed, 19 insertions, 1 deletions

diff --git a/logic/pipeline.cpp b/logic/pipeline.cpp
index c5dfe2d7..7774b02e 100644
--- a/logic/pipeline.cpp
+++ b/logic/pipeline.cpp
@@ -88,6 +88,8 @@ Pose reltrans::apply_pipeline(reltrans_state state, const Pose& value,
                 //qDebug() << "reltrans-interp: START" << tcomp_in_zone_;
                 cur = true;
                 interp_timer.start();
+                interp_phase_timer.start();
+                RC_phase = 0;
             }
 
             in_zone = tcomp_in_zone_;
@@ -114,10 +116,20 @@ Pose reltrans::apply_pipeline(reltrans_state state, const Pose& value,
 
         if (cur)
         {
+            static constexpr double RC_phases[] = { 2, 1, .5, .1, };
+            static constexpr double RC_time_deltas[] = { 1, .25, 25., };
+
             const double dt = interp_timer.elapsed_seconds();
             interp_timer.start();
 
-            constexpr double RC = .1;
+            if (RC_phase + 1 != std::size(RC_phases) &&
+                interp_phase_timer.elapsed_seconds() > RC_time_deltas[RC_phase])
+            {
+                RC_phase++;
+                interp_phase_timer.start();
+            }
+
+            const double RC = RC_phases[RC_phase];
             const double alpha = dt/(dt+RC);
 
             constexpr double eps = .05;
diff --git a/logic/pipeline.hpp b/logic/pipeline.hpp
index 7f618ea1..82a339a3 100644
--- a/logic/pipeline.hpp
+++ b/logic/pipeline.hpp
@@ -42,6 +42,12 @@ class reltrans
 {
     euler_t interp_pos, last_value;
     Timer interp_timer;
+
+    // this implements smooth transition into reltrans mode
+    // once not aiming anymore. see `apply_pipeline()'.
+    Timer interp_phase_timer;
+    unsigned RC_phase;
+
     bool cur = false;
     bool in_zone = false;