BulletSim: tweek step parameters and logic to make walking up steps

closer to SL. This change should address small floor edges acting like
walls, approaching a step at any angle (other than walking backwards)
will allow walking up, and reducing the avatar pop-up when going up
stairs.

OpenSim/Region/Physics/BulletSPlugin/BSActorAvatarMove.cs

@@ -341,7 +341,7 @@ public class BSActorAvatarMove : BSActor
             // float nearFeetHeightMin = m_controllingPrim.RawPosition.Z - (m_controllingPrim.Size.Z / 2f) + 0.05f;
             // Note: there is a problem with the computation of the capsule height. Thus RawPosition is off
             //    from the height. Revisit size and this computation when height is scaled properly.
-            float nearFeetHeightMin = m_controllingPrim.RawPosition.Z - (m_controllingPrim.Size.Z / 2f) - 0.05f;
+            float nearFeetHeightMin = m_controllingPrim.RawPosition.Z - (m_controllingPrim.Size.Z / 2f) - BSParam.AvatarStepGroundFudge;
             float nearFeetHeightMax = nearFeetHeightMin + BSParam.AvatarStepHeight;
 
             // Look for a collision point that is near the character's feet and is oriented the same as the charactor is.
@@ -363,15 +363,25 @@ public class BSActorAvatarMove : BSActor
                             if (touchPosition.Z >= nearFeetHeightMin && touchPosition.Z <= nearFeetHeightMax)
                             {
                                 // This contact is within the 'near the feet' range.
-                                // The normal should be our contact point to the object so it is pointing away
+                                // The step is presumed to be more or less vertical. Thus the Z component should
-                                //    thus the difference between our facing orientation and the normal should be small.
+                                //    be nearly horizontal.
                                 OMV.Vector3 directionFacing = OMV.Vector3.UnitX * m_controllingPrim.RawOrientation;
-                                OMV.Vector3 touchNormal = OMV.Vector3.Normalize(kvp.Value.SurfaceNormal);
+                                OMV.Vector3 touchNormal = OMV.Vector3.Normalize(kvp.Value.SurfaceNormal);
-                                float diff = Math.Abs(OMV.Vector3.Distance(directionFacing, touchNormal));
+                                const float PIOver2 = 1.571f; // Used to make unit vector axis into approx radian angles
-                                if (diff < BSParam.AvatarStepApproachFactor)
+                                // m_physicsScene.DetailLog("{0},BSCharacter.WalkUpStairs,avNormal={1},colNormal={2},diff={3}",
+                                //             m_controllingPrim.LocalID, directionFacing, touchNormal,
+                                //             Math.Abs(OMV.Vector3.Distance(directionFacing, touchNormal)) );
+                                if ((Math.Abs(directionFacing.Z) * PIOver2) < BSParam.AvatarStepAngle
+                                    && (Math.Abs(touchNormal.Z) * PIOver2) < BSParam.AvatarStepAngle)
                                 {
-                                    if (highestTouchPosition.Z < touchPosition.Z)
+                                    // The normal should be our contact point to the object so it is pointing away
-                                        highestTouchPosition = touchPosition;
+                                    //    thus the difference between our facing orientation and the normal should be small.
+                                    float diff = Math.Abs(OMV.Vector3.Distance(directionFacing, touchNormal));
+                                    if (diff < BSParam.AvatarStepApproachFactor)
+                                    {
+                                        if (highestTouchPosition.Z < touchPosition.Z)
+                                            highestTouchPosition = touchPosition;
+                                    }
                                 }
                             }
                         }

OpenSim/Region/Physics/BulletSPlugin/BSParam.cs

@@ -153,6 +153,8 @@ public static class BSParam
 	public static int AvatarJumpFrames { get; private set; }
 	public static float AvatarBelowGroundUpCorrectionMeters { get; private set; }
 	public static float AvatarStepHeight { get; private set; }
+	public static float AvatarStepAngle { get; private set; }
+	public static float AvatarStepGroundFudge { get; private set; }
 	public static float AvatarStepApproachFactor { get; private set; }
 	public static float AvatarStepForceFactor { get; private set; }
 	public static float AvatarStepUpCorrectionFactor { get; private set; }
@@ -614,13 +616,17 @@ public static class BSParam
 	    new ParameterDefn<int>("AvatarJumpFrames", "Number of frames to allow jump forces. Changes jump height.",
             4 ),
 	    new ParameterDefn<float>("AvatarStepHeight", "Height of a step obstacle to consider step correction",
-            0.6f ) ,
+            0.999f ) ,
+	    new ParameterDefn<float>("AvatarStepAngle", "The angle (in radians) for a vertical surface to be considered a step",
+            0.3f ) ,
+	    new ParameterDefn<float>("AvatarStepGroundFudge", "Fudge factor subtracted from avatar base when comparing collision height",
+            0.1f ) ,
 	    new ParameterDefn<float>("AvatarStepApproachFactor", "Factor to control angle of approach to step (0=straight on)",
-            0.6f ),
+            2f ),
 	    new ParameterDefn<float>("AvatarStepForceFactor", "Controls the amount of force up applied to step up onto a step",
-            1.0f ),
+            0f ),
 	    new ParameterDefn<float>("AvatarStepUpCorrectionFactor", "Multiplied by height of step collision to create up movement at step",
-            2.0f ),
+            0.8f ),
 	    new ParameterDefn<int>("AvatarStepSmoothingSteps", "Number of frames after a step collision that we continue walking up stairs",
             1 ),
 

bin/OpenSimDefaults.ini

@@ -1070,6 +1070,17 @@
     AvatarHeightMidFudge = 0      ; Adjustment at mid point of avatar height range
     AvatarHeightHighFudge = 0     ; Adjustment at high end of height range
 
+    ; Avatar walk-up-stairs parameters
+    ; If an avatar collides with an object 'close to its feet', the avatar will be
+    ;    moved/pushed up do simulate stepping up.
+    ;AvatarStepHeight = 0.6f             ; The height, below which is considered a step collision.
+    ;AvatarStepAngle = 0.3f              ; The angle from vertical (in radians) to consider a surface a step
+    ;AvatarStepApproachFactor = 2f       ; Approach angle factor. O=straight on, .6=~45 degrees.
+    ;AvatarStepGroundFudge = 0.1f        ; Fudge added to bottom of avatar below which step collisions happen
+    ;AvatarStepForceFactor = 0f          ; Avatar is pushed up by its mass times this factor
+    ;AvatarStepUpCorrectionFactor = 0.8f ; Avatar is displaced up the collision height times this factor
+    ;AvatarStepSmoothingSteps = 1        ; Number of frames after a step collision that up correction is applied
+
     ; Terminal velocity of a falling avatar
     ; This is the same http://en.wikipedia.org/wiki/Terminal_velocity#Examples
     ; negative for a downward speed.