diff --git a/source/core/gamecontrol.cpp b/source/core/gamecontrol.cpp
index c674db4de..7d1faa9a3 100644
--- a/source/core/gamecontrol.cpp
+++ b/source/core/gamecontrol.cpp
@@ -1436,6 +1436,79 @@ fixed_t getincangleq16(fixed_t a, fixed_t na)
 	}
 }
 
+//---------------------------------------------------------------------------
+//
+// PlayerHorizon struct functions.
+//
+//---------------------------------------------------------------------------
+
+void PlayerHorizon::backup()
+{
+	ohoriz = horiz;
+	ohorizoff = horizoff;
+}
+
+void PlayerHorizon::addadjustment(double value)
+{
+	if (!cl_syncinput)
+	{
+		adjustment += value;
+	}
+	else
+	{
+		horiz += q16horiz(FloatToFixed(value));
+	}
+}
+
+void PlayerHorizon::resetadjustment()
+{
+	adjustment = 0;
+}
+
+void PlayerHorizon::settarget(double value, bool backup)
+{
+	if (!cl_syncinput)
+	{
+		target = FloatToFixed(value);
+		if (target == 0) target += 1;
+	}
+	else
+	{
+		horiz = q16horiz(FloatToFixed(value));
+		if (backup) ohoriz = horiz;
+	}
+}
+
+void PlayerHorizon::processhelpers(double const scaleAdjust)
+{
+	if (target)
+	{
+		horiz += q16horiz(xs_CRoundToInt(scaleAdjust * (target - horiz.asq16())));
+
+		if (abs(horiz.asq16() - target) < FRACUNIT)
+		{
+			horiz = q16horiz(target);
+			target = 0;
+		}
+	}
+	else if (adjustment)
+	{
+		horiz += q16horiz(FloatToFixed(scaleAdjust * adjustment));
+	}
+}
+
+fixedhoriz PlayerHorizon::sum()
+{
+	return horiz + horizoff;
+}
+
+fixedhoriz PlayerHorizon::interpolatedsum(double const smoothratio)
+{
+	fixedhoriz prev = ohoriz + ohorizoff;
+	fixedhoriz curr = horiz + horizoff;
+	return q16horiz(prev.asq16() + mulscale16(curr.asq16() - prev.asq16(), smoothratio));
+}
+
 //---------------------------------------------------------------------------
 //
 // Player's movement function, called from game's ticker or from gi->GetInput() as required.
diff --git a/source/core/gamecontrol.h b/source/core/gamecontrol.h
index b2dd5eb20..1f0354453 100644
--- a/source/core/gamecontrol.h
+++ b/source/core/gamecontrol.h
@@ -74,72 +74,13 @@ struct PlayerHorizon
 	fixed_t target;
 	double adjustment;
 
-	void backup()
-	{
-		ohoriz = horiz;
-		ohorizoff = horizoff;
-	}
-
-	void addadjustment(double value)
-	{
-		if (!cl_syncinput)
-		{
-			adjustment += value;
-		}
-		else
-		{
-			horiz += q16horiz(FloatToFixed(value));
-		}
-	}
-
-	void resetadjustment()
-	{
-		adjustment = 0;
-	}
-
-	void settarget(double value, bool backup = false)
-	{
-		if (!cl_syncinput)
-		{
-			target = FloatToFixed(value);
-			if (target == 0) target += 1;
-		}
-		else
-		{
-			horiz = q16horiz(FloatToFixed(value));
-			if (backup) ohoriz = horiz;
-		}
-	}
-
-	void processhelpers(double const scaleAdjust)
-	{
-		if (target)
-		{
-			horiz += q16horiz(xs_CRoundToInt(scaleAdjust * (target - horiz.asq16())));
-
-			if (abs(horiz.asq16() - target) < FRACUNIT)
-			{
-				horiz = q16horiz(target);
-				target = 0;
-			}
-		}
-		else if (adjustment)
-		{
-			horiz += q16horiz(FloatToFixed(scaleAdjust * adjustment));
-		}
-	}
-
-	fixedhoriz sum()
-	{
-		return horiz + horizoff;
-	}
-
-	fixedhoriz interpolatedsum(double const smoothratio)
-	{
-		fixedhoriz prev = ohoriz + ohorizoff;
-		fixedhoriz curr = horiz + horizoff;
-		return q16horiz(prev.asq16() + mulscale16(curr.asq16() - prev.asq16(), smoothratio));
-	}
+	void backup();
+	void addadjustment(double value);
+	void resetadjustment();
+	void settarget(double value, bool backup = false);
+	void processhelpers(double const scaleAdjust);
+	fixedhoriz sum();
+	fixedhoriz interpolatedsum(double const smoothratio);
 };
 
 void processMovement(InputPacket* currInput, InputPacket* inputBuffer, ControlInfo* const hidInput, double const scaleAdjust, int const drink_amt = 0, bool const allowstrafe = true, double const turnscale = 1);