From 87b313d715f02a830f48059228a7264dc67fe77d Mon Sep 17 00:00:00 2001
From: "erwin.coumans" <erwin.coumans@08e121b0-ae19-0410-a57b-3be3395fd4fd>
Date: Wed, 3 Feb 2010 23:58:48 +0000
Subject: [PATCH] Add flags to btRigidBody to disable world gravity.

Use setFlags/getFlags with BT_DISABLE_WORLD_GRAVITY

See http://code.google.com/p/bullet/issues/detail?id=324
---
 .../Dynamics/btDiscreteDynamicsWorld.cpp       |  6 +++---
 src/BulletDynamics/Dynamics/btRigidBody.cpp    |  2 ++
 src/BulletDynamics/Dynamics/btRigidBody.h      | 18 +++++++++++++++++-
 3 files changed, 22 insertions(+), 4 deletions(-)

diff --git a/src/BulletDynamics/Dynamics/btDiscreteDynamicsWorld.cpp b/src/BulletDynamics/Dynamics/btDiscreteDynamicsWorld.cpp
index d3ac0b5ed..c0790aa31 100644
--- a/src/BulletDynamics/Dynamics/btDiscreteDynamicsWorld.cpp
+++ b/src/BulletDynamics/Dynamics/btDiscreteDynamicsWorld.cpp
@@ -345,7 +345,7 @@ void	btDiscreteDynamicsWorld::setGravity(const btVector3& gravity)
 	for ( int i=0;i<m_nonStaticRigidBodies.size();i++)
 	{
 		btRigidBody* body = m_nonStaticRigidBodies[i];
-		if (body->isActive())
+		if (body->isActive() && !(body->getFlags() &BT_DISABLE_WORLD_GRAVITY))
 		{
 			body->setGravity(gravity);
 		}
@@ -380,7 +380,7 @@ void	btDiscreteDynamicsWorld::removeRigidBody(btRigidBody* body)
 
 void	btDiscreteDynamicsWorld::addRigidBody(btRigidBody* body)
 {
-	if (!body->isStaticOrKinematicObject())
+	if (!body->isStaticOrKinematicObject() && !(body->getFlags() &BT_DISABLE_WORLD_GRAVITY))
 	{
 		body->setGravity(m_gravity);
 	}
@@ -405,7 +405,7 @@ void	btDiscreteDynamicsWorld::addRigidBody(btRigidBody* body)
 
 void	btDiscreteDynamicsWorld::addRigidBody(btRigidBody* body, short group, short mask)
 {
-	if (!body->isStaticOrKinematicObject())
+	if (!body->isStaticOrKinematicObject() && !(body->getFlags() &BT_DISABLE_WORLD_GRAVITY))
 	{
 		body->setGravity(m_gravity);
 	}
diff --git a/src/BulletDynamics/Dynamics/btRigidBody.cpp b/src/BulletDynamics/Dynamics/btRigidBody.cpp
index 48c037e50..1ab07dda5 100644
--- a/src/BulletDynamics/Dynamics/btRigidBody.cpp
+++ b/src/BulletDynamics/Dynamics/btRigidBody.cpp
@@ -86,6 +86,8 @@ void	btRigidBody::setupRigidBody(const btRigidBody::btRigidBodyConstructionInfo&
     setDamping(constructionInfo.m_linearDamping, constructionInfo.m_angularDamping);
 	updateInertiaTensor();
 
+	m_rigidbodyFlags = 0;
+
 }
 
 
diff --git a/src/BulletDynamics/Dynamics/btRigidBody.h b/src/BulletDynamics/Dynamics/btRigidBody.h
index 708b2251e..1376ca544 100644
--- a/src/BulletDynamics/Dynamics/btRigidBody.h
+++ b/src/BulletDynamics/Dynamics/btRigidBody.h
@@ -38,6 +38,10 @@ extern bool gDisableDeactivation;
 #endif //BT_USE_DOUBLE_PRECISION
 
 
+enum	btRigidBodyFlags
+{
+	BT_DISABLE_WORLD_GRAVITY = 1
+};
 
 
 ///The btRigidBody is the main class for rigid body objects. It is derived from btCollisionObject, so it keeps a pointer to a btCollisionShape.
@@ -83,6 +87,10 @@ class btRigidBody  : public btCollisionObject
 	//keep track of typed constraints referencing this rigid body
 	btAlignedObjectArray<btTypedConstraint*> m_constraintRefs;
 
+	int				m_rigidbodyFlags;
+	
+	int				m_debugBodyId;
+
 public:
 
 	///The btRigidBodyConstructionInfo structure provides information to create a rigid body. Setting mass to zero creates a fixed (non-dynamic) rigid body.
@@ -503,7 +511,15 @@ public:
 		return m_constraintRefs.size();
 	}
 
-	int	m_debugBodyId;
+	void	setFlags(int flags)
+	{
+		m_rigidbodyFlags = flags;
+	}
+
+	int getFlags() const
+	{
+		return m_rigidbodyFlags;
+	}
 
 	virtual	int	calculateSerializeBufferSize()	const;