BulletSim: make llBuoyancy work. For some reason, Bullet resets an

object's individual gravity to the world gravity when the object
is added to the physical world.

3 files changed, 13 insertions, 5 deletions

diff --git a/OpenSim/Region/Physics/BulletSPlugin/BSDynamics.cs b/OpenSim/Region/Physics/BulletSPlugin/BSDynamics.cs
index 3fde57b..a8edd23 100644
--- a/OpenSim/Region/Physics/BulletSPlugin/BSDynamics.cs
+++ b/OpenSim/Region/Physics/BulletSPlugin/BSDynamics.cs
@@ -573,6 +573,9 @@ namespace OpenSim.Region.Physics.BulletSPlugin
                 BulletSimAPI.SetMassProps2(Prim.PhysBody.ptr, m_vehicleMass, localInertia);
                 BulletSimAPI.UpdateInertiaTensor2(Prim.PhysBody.ptr);
 
+                Vector3 grav = PhysicsScene.DefaultGravity * (1f - Prim.Buoyancy);
+                BulletSimAPI.SetGravity2(Prim.PhysBody.ptr, grav);
+
                 VDetailLog("{0},BSDynamics.Refresh,mass={1},frict={2},inert={3},aDamp={4}",
                                 Prim.LocalID, m_vehicleMass, friction, localInertia, angularDamping);
             }
diff --git a/OpenSim/Region/Physics/BulletSPlugin/BSPrim.cs b/OpenSim/Region/Physics/BulletSPlugin/BSPrim.cs
index 159f79f..0d13096 100644
--- a/OpenSim/Region/Physics/BulletSPlugin/BSPrim.cs
+++ b/OpenSim/Region/Physics/BulletSPlugin/BSPrim.cs
@@ -422,20 +422,24 @@ public sealed class BSPrim : BSPhysObject
                     BulletSimAPI.RemoveObjectFromWorld2(PhysicsScene.World.ptr, PhysBody.ptr);
                 }
 
-                float grav = PhysicsScene.Params.gravity * (1f - _buoyancy);
-                BulletSimAPI.SetGravity2(PhysBody.ptr, new OMV.Vector3(0f, 0f, grav));
-
                 Inertia = BulletSimAPI.CalculateLocalInertia2(PhysShape.ptr, physMass);
                 BulletSimAPI.SetMassProps2(PhysBody.ptr, physMass, Inertia);
                 BulletSimAPI.UpdateInertiaTensor2(PhysBody.ptr);
+
                 // center of mass is at the zero of the object
                 // DEBUG DEBUG BulletSimAPI.SetCenterOfMassByPosRot2(PhysBody.ptr, ForcePosition, ForceOrientation);
-                DetailLog("{0},BSPrim.UpdateMassProperties,mass={1},localInertia={2}", LocalID, physMass, Inertia);
+                DetailLog("{0},BSPrim.UpdateMassProperties,mass={1},localInertia={2},inWorld={3}", LocalID, physMass, Inertia, inWorld);
 
                 if (inWorld)
                 {
                     BulletSimAPI.AddObjectToWorld2(PhysicsScene.World.ptr, PhysBody.ptr);
                 }
+
+                // Must set gravity after it has been added to the world because, for unknown reasons,
+                //     adding the object resets the object's gravity to world gravity
+                OMV.Vector3 grav = PhysicsScene.DefaultGravity * (1f - Buoyancy);
+                BulletSimAPI.SetGravity2(PhysBody.ptr, grav);
+
             }
         }
     }
diff --git a/OpenSim/Region/Physics/BulletSPlugin/BulletSimTODO.txt b/OpenSim/Region/Physics/BulletSPlugin/BulletSimTODO.txt
index 35cb8f3..9d07d72 100755
--- a/OpenSim/Region/Physics/BulletSPlugin/BulletSimTODO.txt
+++ b/OpenSim/Region/Physics/BulletSPlugin/BulletSimTODO.txt
@@ -58,7 +58,6 @@ Incorporate inter-relationship of angular corrections. For instance, angularDefl
 
 BULLETSIM TODO LIST:
 =================================================
-In SL, perfect spheres don't seem to have rolling friction. Add special case.
 Avatar density is WAY off. Compare and calibrate with what's in SL.
 Revisit CollisionMargin. Builders notice the 0.04 spacing between prims.
 Duplicating a physical prim causes old prim to jump away
@@ -146,6 +145,8 @@ Is there are more efficient method of implementing pre and post step actions?
         See http://www.codeproject.com/Articles/29922/Weak-Events-in-C
 
 Physics Arena central pyramid: why is one side permiable?
+
+In SL, perfect spheres don't seem to have rolling friction. Add special case.
 Enforce physical parameter min/max:
         Gravity: [-1, 28]
         Friction: [0, 255]