From 269c200c8f5e659189579c2b93e91d2a93e609ac Mon Sep 17 00:00:00 2001
From: scrawl <scrawl@baseoftrash.de>
Date: Tue, 16 Sep 2014 03:15:04 +0200
Subject: [PATCH] Fix jump velocity mechanics (Fixes #1708)

---
 apps/openmw/mwmechanics/character.cpp | 38 +++++++++------------------
 apps/openmw/mwworld/physicssystem.cpp | 20 +++++++-------
 2 files changed, 24 insertions(+), 34 deletions(-)

diff --git a/apps/openmw/mwmechanics/character.cpp b/apps/openmw/mwmechanics/character.cpp
index 566ca77aa..cba51b835 100644
--- a/apps/openmw/mwmechanics/character.cpp
+++ b/apps/openmw/mwmechanics/character.cpp
@@ -1277,15 +1277,7 @@ void CharacterController::update(float duration)
 
         //Ogre::Vector3 vec = cls.getMovementVector(mPtr);
         Ogre::Vector3 vec(cls.getMovementSettings(mPtr).mPosition);
-        if(vec.z > 0.0f) // to avoid slow-down when jumping
-        {
-            Ogre::Vector2 vecXY = Ogre::Vector2(vec.x, vec.y);
-            vecXY.normalise();
-            vec.x = vecXY.x;
-            vec.y = vecXY.y;
-        }
-        else
-            vec.normalise();
+        vec.normalise();
 
         if(mHitState != CharState_None && mJumpState == JumpState_None)
             vec = Ogre::Vector3(0.0f);
@@ -1383,28 +1375,24 @@ void CharacterController::update(float duration)
             mJumpState = JumpState_Falling;
 
             // This is a guess. All that seems to be known is that "While the player is in the
-            // air, fJumpMoveBase and fJumpMoveMult governs air control." Assuming Acrobatics
-            // plays a role, this makes the most sense.
-            float mult = 0.0f;
-            if(cls.isNpc())
-            {
-                const NpcStats &stats = cls.getNpcStats(mPtr);
-                static const float fJumpMoveBase = gmst.find("fJumpMoveBase")->getFloat();
-                static const float fJumpMoveMult = gmst.find("fJumpMoveMult")->getFloat();
+            // air, fJumpMoveBase and fJumpMoveMult governs air control". What does fJumpMoveMult do?
+            static const float fJumpMoveBase = gmst.find("fJumpMoveBase")->getFloat();
 
-                mult = fJumpMoveBase +
-                       (stats.getSkill(ESM::Skill::Acrobatics).getModified()/100.0f *
-                        fJumpMoveMult);
-            }
-
-            vec.x *= mult;
-            vec.y *= mult;
+            vec.x *= fJumpMoveBase;
+            vec.y *= fJumpMoveBase;
             vec.z  = 0.0f;
         }
         else if(vec.z > 0.0f && mJumpState == JumpState_None)
         {
             // Started a jump.
-            vec.z = cls.getJump(mPtr);
+            float z = cls.getJump(mPtr);
+            if(vec.x == 0 && vec.y == 0)
+                vec = Ogre::Vector3(0.0f, 0.0f, z);
+            else
+            {
+                Ogre::Vector3 lat = Ogre::Vector3(vec.x, vec.y, 0.0f).normalisedCopy();
+                vec = Ogre::Vector3(lat.x, lat.y, 1.0f) * z * 0.707f;
+            }
 
             // advance acrobatics
             if (mPtr.getRefData().getHandle() == "player")
diff --git a/apps/openmw/mwworld/physicssystem.cpp b/apps/openmw/mwworld/physicssystem.cpp
index 51aae2bc3..5a28e4460 100644
--- a/apps/openmw/mwworld/physicssystem.cpp
+++ b/apps/openmw/mwworld/physicssystem.cpp
@@ -299,18 +299,20 @@ namespace MWWorld
                 // not in water nor can fly, so need to deal with gravity
                 if(!physicActor->getOnGround()) // if current OnGround status is false, must be falling or jumping
                 {
-                    // If falling, add part of the incoming velocity with the current inertia
-                    // TODO: but we could be jumping up?
-                    velocity = velocity * time + physicActor->getInertialForce();
-
-                    // avoid getting infinite inertia in air
+                    // If falling or jumping up, add part of the incoming velocity with the current inertia,
+                    // but don't allow increasing inertia beyond actor's speed (except on the initial jump impulse)
                     float actorSpeed = ptr.getClass().getSpeed(ptr);
-                    float speedXY = Ogre::Vector2(velocity.x, velocity.y).length();
-                    if (speedXY > actorSpeed) 
+                    float cap = std::max(actorSpeed, Ogre::Vector2(physicActor->getInertialForce().x, physicActor->getInertialForce().y).length());
+                    Ogre::Vector3 newVelocity = velocity + physicActor->getInertialForce();
+                    if (Ogre::Vector2(newVelocity.x, newVelocity.y).squaredLength() > cap*cap)
                     {
-                        velocity.x *= actorSpeed / speedXY;
-                        velocity.y *= actorSpeed / speedXY;
+                        velocity = newVelocity;
+                        float speedXY = Ogre::Vector2(velocity.x, velocity.y).length();
+                        velocity.x *= cap / speedXY;
+                        velocity.y *= cap / speedXY;
                     }
+                    else
+                        velocity = newVelocity;
                 }
                 inertia = velocity; // NOTE: velocity is for z axis only in this code block