BulletSim: add adjustment for avatar capsule height scaling. Makes

avatar standing on ground view better and enables tuning.

OpenSim/Region/Physics/BulletSPlugin/BSCharacter.cs

@@ -1,4 +1,4 @@
-/*
+/*
  * Copyright (c) Contributors, http://opensimulator.org/
  * See CONTRIBUTORS.TXT for a full list of copyright holders.
  *
@@ -649,12 +649,12 @@ public sealed class BSCharacter : BSPhysObject
         OMV.Vector3 newScale;
 
         // Bullet's capsule total height is the "passed height + radius * 2";
-        // The base capsule is 1 diameter and 2 height (passed radius=0.5, passed height = 1)
+        // The base capsule is 1 unit in diameter and 2 units in height (passed radius=0.5, passed height = 1)
         // The number we pass in for 'scaling' is the multiplier to get that base
         //     shape to be the size desired.
         // So, when creating the scale for the avatar height, we take the passed height
         //     (size.Z) and remove the caps.
-        // Another oddity of the Bullet capsule implementation is that it presumes the Y
+        // An oddity of the Bullet capsule implementation is that it presumes the Y
         //     dimension is the radius of the capsule. Even though some of the code allows
         //     for a asymmetrical capsule, other parts of the code presume it is cylindrical.
 
@@ -662,8 +662,27 @@ public sealed class BSCharacter : BSPhysObject
         newScale.X = size.X / 2f;
         newScale.Y = size.Y / 2f;
 
+        float heightAdjust = BSParam.AvatarHeightMidFudge;
+        if (BSParam.AvatarHeightLowFudge != 0f || BSParam.AvatarHeightHighFudge != 0f)
+        {
+            // An avatar is between 1.61 and 2.12 meters. Midpoint is 1.87m.
+            // The "times 4" relies on the fact that the difference from the midpoint to the extremes is exactly 0.25
+            float midHeightOffset = size.Z - 1.87f;
+            if (midHeightOffset < 0f)
+            {
+                // Small avatar. Add the adjustment based on the distance from midheight
+                heightAdjust += -1f * midHeightOffset * 4f * BSParam.AvatarHeightLowFudge;
+            }
+            else
+            {
+                // Large avatar. Add the adjustment based on the distance from midheight
+                heightAdjust += midHeightOffset * 4f * BSParam.AvatarHeightHighFudge;
+            }
+        }
         // The total scale height is the central cylindar plus the caps on the two ends.
-        newScale.Z = (size.Z + (Math.Min(size.X, size.Y) * 2)) / 2f;
+        newScale.Z = (size.Z + (Math.Min(size.X, size.Y) * 2) + heightAdjust) / 2f;
+        // m_log.DebugFormat("{0} ComputeAvatarScale: size={1},adj={2},scale={3}", LogHeader, size, heightAdjust, newScale);
+
         // If smaller than the endcaps, just fake like we're almost that small
         if (newScale.Z < 0)
             newScale.Z = 0.1f;

OpenSim/Region/Physics/BulletSPlugin/BSParam.cs

@@ -125,6 +125,9 @@ public static class BSParam
     public static float AvatarCapsuleWidth { get; private set; }
     public static float AvatarCapsuleDepth { get; private set; }
     public static float AvatarCapsuleHeight { get; private set; }
+    public static float AvatarHeightLowFudge { get; private set; }
+    public static float AvatarHeightMidFudge { get; private set; }
+    public static float AvatarHeightHighFudge { get; private set; }
 	public static float AvatarContactProcessingThreshold { get; private set; }
 	public static float AvatarBelowGroundUpCorrectionMeters { get; private set; }
 	public static float AvatarStepHeight { get; private set; }
@@ -539,6 +542,12 @@ public static class BSParam
             0.45f ),
         new ParameterDefn<float>("AvatarCapsuleHeight", "Default height of space around avatar",
             1.5f ),
+        new ParameterDefn<float>("AvatarHeightLowFudge", "A fudge factor to make small avatars stand on the ground",
+            -0.2f ),
+        new ParameterDefn<float>("AvatarHeightMidFudge", "A fudge distance to adjust average sized avatars to be standing on ground",
+            0.1f ),
+        new ParameterDefn<float>("AvatarHeightHighFudge", "A fudge factor to make tall avatars stand on the ground",
+            0.1f ),
 	    new ParameterDefn<float>("AvatarContactProcessingThreshold", "Distance from capsule to check for collisions",
             0.1f ),
 	    new ParameterDefn<float>("AvatarBelowGroundUpCorrectionMeters", "Meters to move avatar up if it seems to be below ground",