From 6a5d08819725a836a4072dec3bd3f84a1bd39ffb Mon Sep 17 00:00:00 2001
From: Robert Adams
Date: Thu, 24 Jan 2013 16:26:04 -0800
Subject: BulletSim: reduce the force of gravity on ground vehicles when they
 are on the ground. Makes them a little more stable.

---
 OpenSim/Region/Physics/BulletSPlugin/BSDynamics.cs | 11 +++++++++++
 1 file changed, 11 insertions(+)

(limited to 'OpenSim/Region/Physics/BulletSPlugin/BSDynamics.cs')

diff --git a/OpenSim/Region/Physics/BulletSPlugin/BSDynamics.cs b/OpenSim/Region/Physics/BulletSPlugin/BSDynamics.cs
index f1ef449..7ad7c89 100644
--- a/OpenSim/Region/Physics/BulletSPlugin/BSDynamics.cs
+++ b/OpenSim/Region/Physics/BulletSPlugin/BSDynamics.cs
@@ -158,6 +158,12 @@ namespace OpenSim.Region.Physics.BulletSPlugin
             get { return (Type != Vehicle.TYPE_NONE && Prim.IsPhysicallyActive); }
         }
 
+        // Return 'true' if this a vehicle that should be sitting on the ground
+        public bool IsGroundVehicle
+        {
+            get { return (Type == Vehicle.TYPE_CAR || Type == Vehicle.TYPE_SLED); }
+        }
+
         #region Vehicle parameter setting
         internal void ProcessFloatVehicleParam(Vehicle pParam, float pValue)
         {
@@ -1176,6 +1182,11 @@ namespace OpenSim.Region.Physics.BulletSPlugin
         private void ApplyGravity(float pTimeStep)
         {
             Vector3 appliedGravity = m_VehicleGravity * m_vehicleMass;
+
+            // Hack to reduce downward force if the vehicle is probably sitting on the ground
+            if (Prim.IsColliding && IsGroundVehicle)
+                appliedGravity *= 0.2f;
+
             VehicleAddForce(appliedGravity);
 
             VDetailLog("{0},  MoveLinear,applyGravity,vehGrav={1},appliedForce-{2}", 
-- 
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