BulletSim: remove friction calcuation from BSMotor and move linear and

angular friction computation into linear and angular movement code.
The friction wasn't being applied properly. This will make it so vehicles
don't drift as much and the drift is tunable by changing the friction
timescales.

1 files changed, 14 insertions, 49 deletions

diff --git a/OpenSim/Region/Physics/BulletSPlugin/BSMotors.cs b/OpenSim/Region/Physics/BulletSPlugin/BSMotors.cs
index 0128d8d..ef662b5 100755
--- a/OpenSim/Region/Physics/BulletSPlugin/BSMotors.cs
+++ b/OpenSim/Region/Physics/BulletSPlugin/BSMotors.cs
@@ -65,13 +65,11 @@ public abstract class BSMotor
 }
 
 // Motor which moves CurrentValue to TargetValue over TimeScale seconds.
-// The TargetValue decays in TargetValueDecayTimeScale and
-//     the CurrentValue will be held back by FrictionTimeScale.
+// The TargetValue decays in TargetValueDecayTimeScale.
 // This motor will "zero itself" over time in that the targetValue will
 //    decay to zero and the currentValue will follow it to that zero.
 //    The overall effect is for the returned correction value to go from large
-//    values (the total difference between current and target minus friction)
-//    to small and eventually zero values.
+//    values to small and eventually zero values.
 // TimeScale and TargetDelayTimeScale may be 'infinite' which means no decay.
 
 // For instance, if something is moving at speed X and the desired speed is Y,
@@ -88,7 +86,6 @@ public class BSVMotor : BSMotor
 
     public virtual float TimeScale { get; set; }
     public virtual float TargetValueDecayTimeScale { get; set; }
-    public virtual Vector3 FrictionTimescale { get; set; }
     public virtual float Efficiency { get; set; }
 
     public virtual float ErrorZeroThreshold { get; set; }
@@ -111,16 +108,14 @@ public class BSVMotor : BSMotor
     {
         TimeScale = TargetValueDecayTimeScale = BSMotor.Infinite;
         Efficiency = 1f;
-        FrictionTimescale = BSMotor.InfiniteVector;
         CurrentValue = TargetValue = Vector3.Zero;
         ErrorZeroThreshold = 0.001f;
     }
-    public BSVMotor(string useName, float timeScale, float decayTimeScale, Vector3 frictionTimeScale, float efficiency)
+    public BSVMotor(string useName, float timeScale, float decayTimeScale, float efficiency)
         : this(useName)
     {
         TimeScale = timeScale;
         TargetValueDecayTimeScale = decayTimeScale;
-        FrictionTimescale = frictionTimeScale;
         Efficiency = efficiency;
         CurrentValue = TargetValue = Vector3.Zero;
     }
@@ -165,26 +160,11 @@ public class BSVMotor : BSMotor
                 TargetValue *= (1f - decayFactor);
             }
 
-            // The amount we can correct the error is reduced by the friction
-            Vector3 frictionFactor = Vector3.Zero;
-            if (FrictionTimescale != BSMotor.InfiniteVector)
-            {
-                // frictionFactor = (Vector3.One / FrictionTimescale) * timeStep;
-                // Individual friction components can be 'infinite' so compute each separately.
-                frictionFactor.X = (FrictionTimescale.X == BSMotor.Infinite) ? 0f : (1f / FrictionTimescale.X);
-                frictionFactor.Y = (FrictionTimescale.Y == BSMotor.Infinite) ? 0f : (1f / FrictionTimescale.Y);
-                frictionFactor.Z = (FrictionTimescale.Z == BSMotor.Infinite) ? 0f : (1f / FrictionTimescale.Z);
-                frictionFactor *= timeStep;
-                CurrentValue *= (Vector3.One - frictionFactor);
-            }
-
             MDetailLog("{0},  BSVMotor.Step,nonZero,{1},origCurr={2},origTarget={3},timeStep={4},err={5},corr={6}",
                                 BSScene.DetailLogZero, UseName, origCurrVal, origTarget,
                                 timeStep, error, correction);
-            MDetailLog("{0},  BSVMotor.Step,nonZero,{1},tgtDecayTS={2},decayFact={3},frictTS={4},frictFact={5},tgt={6},curr={7}",
-                                BSScene.DetailLogZero, UseName,
-                                TargetValueDecayTimeScale, decayFactor, FrictionTimescale, frictionFactor,
-                                TargetValue, CurrentValue);
+            MDetailLog("{0},  BSVMotor.Step,nonZero,{1},tgtDecayTS={2},decayFact={3},tgt={4},curr={5}",
+                                BSScene.DetailLogZero, UseName, TargetValueDecayTimeScale, decayFactor, TargetValue, CurrentValue);
         }
         else
         {
@@ -235,9 +215,9 @@ public class BSVMotor : BSMotor
         // maximum number of outputs to generate.
         int maxOutput = 50;
         MDetailLog("{0},BSVMotor.Test,{1},===================================== BEGIN Test Output", BSScene.DetailLogZero, UseName);
-        MDetailLog("{0},BSVMotor.Test,{1},timeScale={2},targDlyTS={3},frictTS={4},eff={5},curr={6},tgt={7}",
+        MDetailLog("{0},BSVMotor.Test,{1},timeScale={2},targDlyTS={3},eff={4},curr={5},tgt={6}",
                                 BSScene.DetailLogZero, UseName,
-                                TimeScale, TargetValueDecayTimeScale, FrictionTimescale, Efficiency,
+                                TimeScale, TargetValueDecayTimeScale, Efficiency,
                                 CurrentValue, TargetValue);
 
         LastError = BSMotor.InfiniteVector;
@@ -254,8 +234,8 @@ public class BSVMotor : BSMotor
 
     public override string ToString()
     {
-        return String.Format("<{0},curr={1},targ={2},lastErr={3},decayTS={4},frictTS={5}>",
-            UseName, CurrentValue, TargetValue, LastError, TargetValueDecayTimeScale, FrictionTimescale);
+        return String.Format("<{0},curr={1},targ={2},lastErr={3},decayTS={4}>",
+            UseName, CurrentValue, TargetValue, LastError, TargetValueDecayTimeScale);
     }
 }
 
@@ -265,7 +245,6 @@ public class BSFMotor : BSMotor
 {
     public virtual float TimeScale { get; set; }
     public virtual float TargetValueDecayTimeScale { get; set; }
-    public virtual float FrictionTimescale { get; set; }
     public virtual float Efficiency { get; set; }
 
     public virtual float ErrorZeroThreshold { get; set; }
@@ -283,12 +262,11 @@ public class BSFMotor : BSMotor
         return (err >= -ErrorZeroThreshold && err <= ErrorZeroThreshold);
     }
 
-    public BSFMotor(string useName, float timeScale, float decayTimescale, float friction, float efficiency)
+    public BSFMotor(string useName, float timeScale, float decayTimescale, float efficiency)
         : base(useName)
     {
         TimeScale = TargetValueDecayTimeScale = BSMotor.Infinite;
         Efficiency = 1f;
-        FrictionTimescale = BSMotor.Infinite;
         CurrentValue = TargetValue = 0f;
         ErrorZeroThreshold = 0.01f;
     }
@@ -331,24 +309,11 @@ public class BSFMotor : BSMotor
                 TargetValue *= (1f - decayFactor);
             }
 
-            // The amount we can correct the error is reduced by the friction
-            float frictionFactor = 0f;
-            if (FrictionTimescale != BSMotor.Infinite)
-            {
-                // frictionFactor = (Vector3.One / FrictionTimescale) * timeStep;
-                // Individual friction components can be 'infinite' so compute each separately.
-                frictionFactor = 1f / FrictionTimescale;
-                frictionFactor *= timeStep;
-                CurrentValue *= (1f - frictionFactor);
-            }
-
             MDetailLog("{0},  BSFMotor.Step,nonZero,{1},origCurr={2},origTarget={3},timeStep={4},err={5},corr={6}",
                                 BSScene.DetailLogZero, UseName, origCurrVal, origTarget,
                                 timeStep, error, correction);
-            MDetailLog("{0},  BSFMotor.Step,nonZero,{1},tgtDecayTS={2},decayFact={3},frictTS={4},frictFact={5},tgt={6},curr={7}",
-                                BSScene.DetailLogZero, UseName,
-                                TargetValueDecayTimeScale, decayFactor, FrictionTimescale, frictionFactor,
-                                TargetValue, CurrentValue);
+            MDetailLog("{0},  BSFMotor.Step,nonZero,{1},tgtDecayTS={2},decayFact={3},tgt={4},curr={5}",
+                                BSScene.DetailLogZero, UseName, TargetValueDecayTimeScale, decayFactor, TargetValue, CurrentValue);
         }
         else
         {
@@ -390,8 +355,8 @@ public class BSFMotor : BSMotor
 
     public override string ToString()
     {
-        return String.Format("<{0},curr={1},targ={2},lastErr={3},decayTS={4},frictTS={5}>",
-            UseName, CurrentValue, TargetValue, LastError, TargetValueDecayTimeScale, FrictionTimescale);
+        return String.Format("<{0},curr={1},targ={2},lastErr={3},decayTS={4}>",
+            UseName, CurrentValue, TargetValue, LastError, TargetValueDecayTimeScale);
     }
 
 }