From 3c4868f61362c2c86cef9f98e197362f57ca627b Mon Sep 17 00:00:00 2001
From: Robert Adams
Date: Sun, 20 Jan 2013 19:13:18 -0800
Subject: BulletSim: fix problem of avatar sliding very slowly occasionally
 after stopping walking. Consolidate movement tests into the one prestep
 motion action

---
 .../Region/Physics/BulletSPlugin/BSCharacter.cs    | 75 ++++++++++++----------
 1 file changed, 41 insertions(+), 34 deletions(-)

(limited to 'OpenSim/Region')

diff --git a/OpenSim/Region/Physics/BulletSPlugin/BSCharacter.cs b/OpenSim/Region/Physics/BulletSPlugin/BSCharacter.cs
index 696c4bd..cd279e3 100644
--- a/OpenSim/Region/Physics/BulletSPlugin/BSCharacter.cs
+++ b/OpenSim/Region/Physics/BulletSPlugin/BSCharacter.cs
@@ -56,6 +56,7 @@ public sealed class BSCharacter : BSPhysObject
     private int _physicsActorType;
     private bool _isPhysical;
     private bool _flying;
+    private bool _wasWalking;   // 'true' if the avatar was walking/moving last frame
     private bool _setAlwaysRun;
     private bool _throttleUpdates;
     private bool _floatOnWater;
@@ -83,6 +84,7 @@ public sealed class BSCharacter : BSPhysObject
         _position = pos;
 
         _flying = isFlying;
+        _wasWalking = true;     // causes first step to initialize standing
         _orientation = OMV.Quaternion.Identity;
         _velocity = OMV.Vector3.Zero;
         _buoyancy = ComputeBuoyancyFromFlying(isFlying);
@@ -199,25 +201,51 @@ public sealed class BSCharacter : BSPhysObject
             //     state (flying, colliding, ...). There is code in ODE to do this.
 
             _velocityMotor.Step(timeStep);
-            OMV.Vector3 stepVelocity = _velocityMotor.CurrentValue;
 
-            // If falling, we keep the world's downward vector no matter what the other axis specify.
-            if (!Flying && !IsColliding)
+            // If we're not supposed to be moving, make sure things are zero.
+            if (_velocityMotor.ErrorIsZero() && _velocityMotor.TargetValue.ApproxEquals(OMV.Vector3.Zero, 0.01f))
             {
-                stepVelocity.Z = _velocity.Z;
-                // DetailLog("{0},BSCharacter.MoveMotor,taint,overrideStepZWithWorldZ,stepVel={1}", LocalID, stepVelocity);
+                if (_wasWalking)
+                {
+                    _velocityMotor.Zero();
+                    _velocity = OMV.Vector3.Zero;
+                    PhysicsScene.PE.SetLinearVelocity(PhysBody, OMV.Vector3.Zero);
+                    _currentFriction = BSParam.AvatarStandingFriction;
+                    PhysicsScene.PE.SetFriction(PhysBody, _currentFriction);
+                    // DetailLog("{0},BSCharacter.MoveMotor,taint,stopping,target={1}", LocalID, _velocityMotor.TargetValue);
+                }
+                _wasWalking = false;
             }
+            else
+            {
+                OMV.Vector3 stepVelocity = _velocityMotor.CurrentValue;
+
+                if (_currentFriction != BSParam.AvatarFriction)
+                {
+                    // Probably starting up walking. Set friction to moving friction.
+                    _currentFriction = BSParam.AvatarFriction;
+                    PhysicsScene.PE.SetFriction(PhysBody, _currentFriction);
+                }
 
-            // 'stepVelocity' is now the speed we'd like the avatar to move in. Turn that into an instantanous force.
-            OMV.Vector3 moveForce = (stepVelocity - _velocity) * Mass;
+                // If falling, we keep the world's downward vector no matter what the other axis specify.
+                if (!Flying && !IsColliding)
+                {
+                    stepVelocity.Z = _velocity.Z;
+                    // DetailLog("{0},BSCharacter.MoveMotor,taint,overrideStepZWithWorldZ,stepVel={1}", LocalID, stepVelocity);
+                }
+
+                // 'stepVelocity' is now the speed we'd like the avatar to move in. Turn that into an instantanous force.
+                OMV.Vector3 moveForce = (stepVelocity - _velocity) * Mass;
 
-            // Should we check for move force being small and forcing velocity to zero?
+                // Should we check for move force being small and forcing velocity to zero?
 
-            // Add special movement force to allow avatars to walk up stepped surfaces.
-            moveForce += WalkUpStairs();
+                // Add special movement force to allow avatars to walk up stepped surfaces.
+                moveForce += WalkUpStairs();
 
-            // DetailLog("{0},BSCharacter.MoveMotor,move,stepVel={1},vel={2},mass={3},moveForce={4}", LocalID, stepVelocity, _velocity, Mass, moveForce);
-            PhysicsScene.PE.ApplyCentralImpulse(PhysBody, moveForce);
+                // DetailLog("{0},BSCharacter.MoveMotor,move,stepVel={1},vel={2},mass={3},moveForce={4}", LocalID, stepVelocity, _velocity, Mass, moveForce);
+                PhysicsScene.PE.ApplyCentralImpulse(PhysBody, moveForce);
+                _wasWalking = true;
+            }
         });
     }
 
@@ -560,27 +588,6 @@ public sealed class BSCharacter : BSPhysObject
             PhysicsScene.AssertInTaintTime("BSCharacter.ForceVelocity");
 
             _velocity = value;
-            // Depending on whether the avatar is moving or not, change the friction
-            //    to keep the avatar from slipping around
-            if (_velocity.Length() == 0)
-            {
-                if (_currentFriction != BSParam.AvatarStandingFriction)
-                {
-                    _currentFriction = BSParam.AvatarStandingFriction;
-                    if (PhysBody.HasPhysicalBody)
-                        PhysicsScene.PE.SetFriction(PhysBody, _currentFriction);
-                }
-            }
-            else
-            {
-                if (_currentFriction != BSParam.AvatarFriction)
-                {
-                    _currentFriction = BSParam.AvatarFriction;
-                    if (PhysBody.HasPhysicalBody)
-                        PhysicsScene.PE.SetFriction(PhysBody, _currentFriction);
-                }
-            }
-
             PhysicsScene.PE.SetLinearVelocity(PhysBody, _velocity);
             PhysicsScene.PE.Activate(PhysBody, true);
         }
@@ -855,7 +862,7 @@ public sealed class BSCharacter : BSPhysObject
         _position = entprop.Position;
         _orientation = entprop.Rotation;
 
-        // Smooth velocity. OpenSimulator is very sensitive to changes in velocity of the avatar
+        // Smooth velocity. OpenSimulator is VERY sensitive to changes in velocity of the avatar
         //    and will send agent updates to the clients if velocity changes by more than
         //    0.001m/s. Bullet introduces a lot of jitter in the velocity which causes many
         //    extra updates.
-- 
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