BGE patch: logic optimization part 2: remove inactive sensors from logic manager.

With this patch, only sensors that are connected to 
active states are actually registered in the logic
manager. Inactive sensors won't take any CPU,
especially the Radar and Near sensors that use a
physical object for the detection: these objects
are removed from the physics engine.

To take advantage of this optimization patch, you
need to define very light idle state when the 
objects are inactive: make them transparent, suspend
the physics, keep few sensors active (e,g a message
sensor to wake up), etc.

1 files changed, 23 insertions, 4 deletions

diff --git a/source/gameengine/GameLogic/SCA_IObject.cpp b/source/gameengine/GameLogic/SCA_IObject.cpp
index 25b4af696ea..b0f8decee26 100644
--- a/source/gameengine/GameLogic/SCA_IObject.cpp
+++ b/source/gameengine/GameLogic/SCA_IObject.cpp
@@ -337,12 +337,31 @@ void SCA_IObject::Resume(void)
 
 void SCA_IObject::SetState(unsigned int state)
 {
-	m_state = state;
-	// update the status of the controllers
+	unsigned int tmpstate;
 	SCA_ControllerList::iterator contit;
-	for (contit = m_controllers.begin(); contit != m_controllers.end(); contit++)
+
+	// we will update the state in two steps:
+	// 1) set the new state bits that are 1
+	// 2) clr the new state bits that are 0
+	// This to ensure continuity if a sensor is attached to two states
+	// that are switching state: no need to deactive and reactive the sensor 
+	
+	tmpstate = m_state | state;
+	if (tmpstate != m_state)
+	{
+		// update the status of the controllers
+		for (contit = m_controllers.begin(); contit != m_controllers.end(); contit++)
+		{
+			(*contit)->ApplyState(tmpstate);
+		}
+	}
+	m_state = state;
+	if (m_state != tmpstate)
 	{
-		(*contit)->ApplyState(m_state);
+		for (contit = m_controllers.begin(); contit != m_controllers.end(); contit++)
+		{
+			(*contit)->ApplyState(m_state);
+		}
 	}
 }