From 6062cd4b9c7a3a3e7f05d6f12f27db4b85c14ee7 Mon Sep 17 00:00:00 2001
From: Andrei Kortunov <andrei.kortunov@yandex.ru>
Date: Tue, 26 Sep 2017 13:28:15 +0400
Subject: [PATCH] Make physics framerate configurable

---
 apps/openmw/mwphysics/physicssystem.cpp            |  7 ++++++-
 docs/source/reference/modding/settings/physics.rst | 13 +++++++++++++
 files/settings-default.cfg                         |  4 ++++
 3 files changed, 23 insertions(+), 1 deletion(-)
 create mode 100644 docs/source/reference/modding/settings/physics.rst

diff --git a/apps/openmw/mwphysics/physicssystem.cpp b/apps/openmw/mwphysics/physicssystem.cpp
index ee368ad24..068ff3186 100644
--- a/apps/openmw/mwphysics/physicssystem.cpp
+++ b/apps/openmw/mwphysics/physicssystem.cpp
@@ -24,6 +24,7 @@
 #include <components/esm/loadgmst.hpp>
 #include <components/sceneutil/positionattitudetransform.hpp>
 #include <components/sceneutil/unrefqueue.hpp>
+#include <components/settings/settings.hpp>
 
 #include <components/nifosg/particle.hpp> // FindRecIndexVisitor
 
@@ -1357,7 +1358,11 @@ namespace MWPhysics
         mMovementResults.clear();
 
         mTimeAccum += dt;
-        const float physicsDt = 1.f/60.0f;
+
+        static const float physFramerate = Settings::Manager::getFloat("physics framerate", "Physics");
+
+        // Allow to use a physics framerate between 10 and 60 FPS
+        static const float physicsDt = 1.f / std::max(10.f, std::min(60.f, physFramerate));
 
         const int maxAllowedSteps = 20;
         int numSteps = mTimeAccum / (physicsDt);
diff --git a/docs/source/reference/modding/settings/physics.rst b/docs/source/reference/modding/settings/physics.rst
new file mode 100644
index 000000000..e4f970a79
--- /dev/null
+++ b/docs/source/reference/modding/settings/physics.rst
@@ -0,0 +1,13 @@
+Physics Settings
+################
+
+physics framerate
+---------------
+
+:Type:		floating point
+:Range:		10.0 to 60.0
+:Default:	60.0
+
+Allows to set how frequently an engine will do physics calculations. A default value is 60 times per second.
+This setting allows developers with low-clocked CPUs to test an engine.
+Changing from default value can lead to physics bugs. Change this setting on your own risk, and reset a value to default before filling a physics-related bugreport!
diff --git a/files/settings-default.cfg b/files/settings-default.cfg
index aec667a9c..f4c7f0a4a 100644
--- a/files/settings-default.cfg
+++ b/files/settings-default.cfg
@@ -277,6 +277,10 @@ camera y multiplier = 1.0
 # Invert the vertical axis while not in GUI mode.
 invert y axis = false
 
+[Physics]
+# Framerate of the physics system
+physics framerate = 60.0
+
 [Saves]
 
 # Name of last character played, and default for loading save files.