From c8f519ec0b7db99ae45389ed42b2c79b5405bb0d Mon Sep 17 00:00:00 2001
From: Chelsea Jaggi <feilen1000@gmail.com>
Date: Mon, 27 Jul 2020 18:13:29 -0700
Subject: [PATCH] Smoother (autoturn) smooth turn: estimate frame rate when
 beginning turn (#498)

* Smoother (autoturn) smooth turn: estimate frame rate when beginning turn

* remove log messages and fix formatting
---
 src/tabcontrollers/RotationTabController.cpp | 55 +++++++++++++++++---
 src/tabcontrollers/RotationTabController.h   | 31 ++++++++++-
 2 files changed, 79 insertions(+), 7 deletions(-)

diff --git a/src/tabcontrollers/RotationTabController.cpp b/src/tabcontrollers/RotationTabController.cpp
index 5c38e02..097a1a4 100644
--- a/src/tabcontrollers/RotationTabController.cpp
+++ b/src/tabcontrollers/RotationTabController.cpp
@@ -196,14 +196,11 @@ void RotationTabController::doAutoTurn(
              && m_autoTurnLinearSmoothTurnRemaining != 0 )
         {
             // TODO: implement angular acceleration max?
-            auto deltaMillis
-                = std::chrono::duration_cast<std::chrono::milliseconds>(
-                      currentTime - m_autoTurnLastUpdate )
-                      .count();
+            double deltaSeconds
+                = FrameRates::toDoubleSeconds( m_estimatedFrameRate );
             auto miniDeltaAngle = static_cast<int>(
                 std::abs(
-                    ( deltaMillis * RotationTabController::autoTurnSpeed() )
-                    / 1000 )
+                    ( deltaSeconds * RotationTabController::autoTurnSpeed() ) )
                 * ( m_autoTurnLinearSmoothTurnRemaining < 0 ? -1 : 1 ) );
             if ( std::abs( m_autoTurnLinearSmoothTurnRemaining )
                  < std::abs( miniDeltaAngle ) )
@@ -366,6 +363,52 @@ void RotationTabController::doAutoTurn(
                 } while ( false );
 
                 m_autoTurnWallActive[i] = true;
+                auto delta = currentTime - m_autoTurnLastUpdate;
+                if ( delta
+                     < ( FrameRates::RATE_144HZ + FrameRates::RATE_120HZ ) / 2 )
+                {
+                    m_estimatedFrameRate = FrameRates::RATE_144HZ;
+                }
+                else if ( ( delta >= ( FrameRates::RATE_144HZ
+                                       + FrameRates::RATE_120HZ )
+                                         / 2 )
+                          && ( delta < ( FrameRates::RATE_120HZ
+                                         + FrameRates::RATE_90HZ )
+                                           / 2 ) )
+                {
+                    m_estimatedFrameRate = FrameRates::RATE_120HZ;
+                }
+                else if ( ( delta >= ( FrameRates::RATE_120HZ
+                                       + FrameRates::RATE_90HZ )
+                                         / 2 )
+                          && ( delta < ( FrameRates::RATE_90HZ
+                                         + FrameRates::RATE_72HZ )
+                                           / 2 ) )
+                {
+                    m_estimatedFrameRate = FrameRates::RATE_90HZ;
+                }
+                else if ( ( delta
+                            >= ( FrameRates::RATE_90HZ + FrameRates::RATE_72HZ )
+                                   / 2 )
+                          && ( delta < ( FrameRates::RATE_72HZ
+                                         + FrameRates::RATE_60HZ )
+                                           / 2 ) )
+                {
+                    m_estimatedFrameRate = FrameRates::RATE_72HZ;
+                }
+                else if ( ( delta
+                            >= ( FrameRates::RATE_72HZ + FrameRates::RATE_60HZ )
+                                   / 2 )
+                          && ( delta < ( FrameRates::RATE_60HZ
+                                         + FrameRates::RATE_45HZ )
+                                           / 2 ) )
+                {
+                    m_estimatedFrameRate = FrameRates::RATE_60HZ;
+                }
+                else
+                {
+                    m_estimatedFrameRate = FrameRates::RATE_45HZ;
+                }
             }
             else if ( ( chaperoneQuad.distance
                         > ( RotationTabController::autoTurnActivationDistance()
diff --git a/src/tabcontrollers/RotationTabController.h b/src/tabcontrollers/RotationTabController.h
index 19117eb..df6199a 100644
--- a/src/tabcontrollers/RotationTabController.h
+++ b/src/tabcontrollers/RotationTabController.h
@@ -1,4 +1,3 @@
-
 #pragma once
 
 #include <QObject>
@@ -25,6 +24,35 @@ enum class AutoTurnModes
     LINEAR_SMOOTH_TURN
 };
 
+namespace FrameRates
+{
+    // Each of type std::chrono::time_point::duration
+    constexpr auto RATE_45HZ = std::chrono::duration_cast<
+        std::chrono::steady_clock::time_point::duration>(
+        std::chrono::duration<int, std::ratio<1, 45>>( 1 ) );
+    constexpr auto RATE_60HZ = std::chrono::duration_cast<
+        std::chrono::steady_clock::time_point::duration>(
+        std::chrono::duration<int, std::ratio<1, 60>>( 1 ) );
+    constexpr auto RATE_72HZ = std::chrono::duration_cast<
+        std::chrono::steady_clock::time_point::duration>(
+        std::chrono::duration<int, std::ratio<1, 72>>( 1 ) );
+    constexpr auto RATE_90HZ = std::chrono::duration_cast<
+        std::chrono::steady_clock::time_point::duration>(
+        std::chrono::duration<int, std::ratio<1, 90>>( 1 ) );
+    constexpr auto RATE_120HZ = std::chrono::duration_cast<
+        std::chrono::steady_clock::time_point::duration>(
+        std::chrono::duration<int, std::ratio<1, 120>>( 1 ) );
+    constexpr auto RATE_144HZ = std::chrono::duration_cast<
+        std::chrono::steady_clock::time_point::duration>(
+        std::chrono::duration<int, std::ratio<1, 144>>( 1 ) );
+
+    template <typename T> double toDoubleSeconds( T duration )
+    {
+        return ( static_cast<double>( duration.count() ) * T::period::num )
+               / T::period::den;
+    }
+} // namespace FrameRates
+
 class RotationTabController : public QObject
 {
     Q_OBJECT
@@ -65,6 +93,7 @@ private:
     vr::HmdMatrix34_t m_autoTurnLastHmdUpdate;
     std::vector<utils::ChaperoneQuadData> m_autoTurnChaperoneDistancesLast;
     double m_autoTurnRoundingError = 0.0;
+    std::chrono::steady_clock::time_point::duration m_estimatedFrameRate;
 
     bool m_isHMDActive = false;