SH-1381 FIXED avatar physics behavior is tightly tied to viewer framerate

Breaking up physics into smaller integration steps.

indra/newview/llphysicsmotion.cpp

@@ -43,7 +43,8 @@
 typedef std::map<std::string, std::string> controller_map_t;
 typedef std::map<std::string, F32> default_controller_map_t;
 
-#define MIN_REQUIRED_PIXEL_AREA_AVATAR_PHYSICS_MOTION 0.f;
+#define MIN_REQUIRED_PIXEL_AREA_AVATAR_PHYSICS_MOTION 0.f
+#define TIME_ITERATION_STEP 0.1f
 
 inline F64 llsgn(const F64 a)
 {
@@ -453,7 +454,8 @@ BOOL LLPhysicsMotion::onUpdate(F32 time)
 		return FALSE;
 	}
 	
-        if (time_delta > 3.0)
+	// If less than 1FPS, we don't want to be spending time updating physics at all.
+        if (time_delta > 1.0)
         {
                 mLastTime = time;
                 return FALSE;
@@ -481,6 +483,18 @@ BOOL LLPhysicsMotion::onUpdate(F32 time)
         if (physics_test)
                 behavior_maxeffect = 1.0f;
 
+	BOOL update_visuals = FALSE; 
+	// Break up the physics into a bunch of iterations so that differing framerates will show
+	// roughly the same behavior.
+	for (F32 time_iteration = 0; time_iteration <= time_delta; time_iteration += TIME_ITERATION_STEP)
+	{
+		F32 time_iteration_step = TIME_ITERATION_STEP;
+		if (time_iteration + TIME_ITERATION_STEP > time_delta)
+		{
+			time_iteration_step = time_delta;
+		}
+		
+
 		// mPositon_local should be in normalized 0,1 range already.  Just making sure...
 		F32 position_current_local = llclamp(mPosition_local,
 						     0.0f,
@@ -509,8 +523,8 @@ BOOL LLPhysicsMotion::onUpdate(F32 time)
 		// Calculate velocity and acceleration in parameter space.
 		//
         
-        const F32 velocity_joint_local = calculateVelocity_local(time_delta);
-        const F32 acceleration_joint_local = calculateAcceleration_local(velocity_joint_local, time_delta);
+		const F32 velocity_joint_local = calculateVelocity_local(time_iteration_step);
+		const F32 acceleration_joint_local = calculateAcceleration_local(velocity_joint_local, time_iteration_step);
 
 		//
 		// End velocity and acceleration
@@ -572,7 +586,7 @@ BOOL LLPhysicsMotion::onUpdate(F32 time)
 			velocity_new_local = sin(time*4.0);
 		}
 		// Calculate the new parameters, or remain unchanged if max speed is 0.
-        F32 position_new_local = position_current_local + velocity_new_local*time_delta;
+		F32 position_new_local = position_current_local + velocity_new_local*time_iteration_step;
 		if (behavior_maxeffect == 0)
 			position_new_local = position_user_local;
 
@@ -638,8 +652,6 @@ BOOL LLPhysicsMotion::onUpdate(F32 time)
 		// So only update if the params have changed enough, and also take into account
 		// the graphics LOD settings.
         
-        BOOL update_visuals = FALSE;
-
 		// For non-self, if the avatar is small enough visually, then don't update.
 		const F32 area_for_max_settings = 0.0;
 		const F32 area_for_min_settings = 1400.0;
@@ -669,6 +681,8 @@ BOOL LLPhysicsMotion::onUpdate(F32 time)
 		mPosition_local = position_new_local;
 
 		mPosition_world = joint->getWorldPosition();
+
+	}
 	mLastTime = time;
 
         /*