From 00f3bfba27d0d509c3991ec2450a80ca3c42ff35 Mon Sep 17 00:00:00 2001
From: logzero <core13@gmx.net>
Date: Sat, 24 Dec 2016 23:07:44 +0100
Subject: [PATCH] Use tracer hit height to skip stepping up in movement solver.

---
 apps/openmw/mwphysics/physicssystem.cpp | 12 +++++++++---
 apps/openmw/mwphysics/trace.cpp         |  2 ++
 apps/openmw/mwphysics/trace.h           |  1 +
 3 files changed, 12 insertions(+), 3 deletions(-)

diff --git a/apps/openmw/mwphysics/physicssystem.cpp b/apps/openmw/mwphysics/physicssystem.cpp
index 14e05f101..2a3cb6137 100644
--- a/apps/openmw/mwphysics/physicssystem.cpp
+++ b/apps/openmw/mwphysics/physicssystem.cpp
@@ -396,10 +396,16 @@ namespace MWPhysics
                 }
 
 
+                // We hit something. Check if we can step up.
+                float hitHeight = tracer.mHitPoint.z() - tracer.mEndPos.z() + halfExtents.z();
                 osg::Vec3f oldPosition = newPosition;
-                // We hit something. Try to step up onto it. (NOTE: stepMove does not allow stepping over)
-                // NOTE: stepMove modifies newPosition if successful
-                bool result = stepper.step(newPosition, velocity*remainingTime, remainingTime);
+                bool result = false;
+                if (hitHeight < sStepSizeUp)
+                {
+                    // Try to step up onto it.
+                    // NOTE: stepMove does not allow stepping over, modifies newPosition if successful
+                    result = stepper.step(newPosition, velocity*remainingTime, remainingTime);
+                }
                 if (result)
                 {
                     // don't let pure water creatures move out of water after stepMove
diff --git a/apps/openmw/mwphysics/trace.cpp b/apps/openmw/mwphysics/trace.cpp
index 420ca1a9e..feda68ca5 100644
--- a/apps/openmw/mwphysics/trace.cpp
+++ b/apps/openmw/mwphysics/trace.cpp
@@ -78,6 +78,7 @@ void ActorTracer::doTrace(const btCollisionObject *actor, const osg::Vec3f& star
         mFraction = newTraceCallback.m_closestHitFraction;
         mPlaneNormal = osg::Vec3f(tracehitnormal.x(), tracehitnormal.y(), tracehitnormal.z());
         mEndPos = (end-start)*mFraction + start;
+        mHitPoint = toOsg(newTraceCallback.m_hitPointWorld);
         mHitObject = newTraceCallback.m_hitCollisionObject;
     }
     else
@@ -85,6 +86,7 @@ void ActorTracer::doTrace(const btCollisionObject *actor, const osg::Vec3f& star
         mEndPos = end;
         mPlaneNormal = osg::Vec3f(0.0f, 0.0f, 1.0f);
         mFraction = 1.0f;
+        mHitPoint = end;
         mHitObject = NULL;
     }
 }
diff --git a/apps/openmw/mwphysics/trace.h b/apps/openmw/mwphysics/trace.h
index 7b7d0391e..0297c9e07 100644
--- a/apps/openmw/mwphysics/trace.h
+++ b/apps/openmw/mwphysics/trace.h
@@ -15,6 +15,7 @@ namespace MWPhysics
     {
         osg::Vec3f mEndPos;
         osg::Vec3f mPlaneNormal;
+        osg::Vec3f mHitPoint;
         const btCollisionObject* mHitObject;
 
         float mFraction;