diff --git a/Docs/Changelog_sm5.txt b/Docs/Changelog_sm5.txt
index 4b5ee89309..8dc574e629 100644
--- a/Docs/Changelog_sm5.txt
+++ b/Docs/Changelog_sm5.txt
@@ -4,6 +4,10 @@ The StepMania 5 Changelog covers all post-sm-ssc changes. For a list of changes
 from StepMania 4 alpha 5 to sm-ssc v1.2.5, see Changelog_sm-ssc.txt.
 ________________________________________________________________________________
 
+2014/10/23
+----------
+* [Global] approach, multiapproach, lerp, and lerp_color lua functions added.
+
 2014/10/20
 ----------
 * [StageStats] GetStepsSeconds function added.
diff --git a/Docs/Luadoc/Lua.xml b/Docs/Luadoc/Lua.xml
index de8282d3f5..ab33c6e73d 100644
--- a/Docs/Luadoc/Lua.xml
+++ b/Docs/Luadoc/Lua.xml
@@ -203,6 +203,7 @@
 		<Function name='WriteGamePrefToFile'/>
 		<Function name='WritePrefToFile'/>
 		<Function name='Year'/>
+		<Function name='approach'/>
 		<Function name='assert'/>
 		<Function name='clamp'/>
 		<Function name='class'/>
@@ -219,11 +220,14 @@
 		<Function name='ipairs'/>
 		<Function name='ivalues'/>
 		<Function name='join'/>
+		<Function name='lerp'/>
+		<Function name='lerp_color'/>
 		<Function name='load'/>
 		<Function name='loadfile'/>
 		<Function name='loadstring'/>
 		<Function name='mbstrlen'/>
 		<Function name='module'/>
+		<Function name='multiapproach'/>
 		<Function name='newproxy'/>
 		<Function name='next'/>
 		<Function name='pairs'/>
diff --git a/Docs/Luadoc/LuaDocumentation.xml b/Docs/Luadoc/LuaDocumentation.xml
index e9c33fedd4..ae50abaebf 100644
--- a/Docs/Luadoc/LuaDocumentation.xml
+++ b/Docs/Luadoc/LuaDocumentation.xml
@@ -31,6 +31,10 @@ save yourself some time, copy this for undocumented things:
 	<Function name='Alpha' theme='_fallback' return='color' arguments='color c, float percent'>
 		[02 Colors.lua] Returns a <code>color</code> with the specified alpha.
 	</Function>
+	<Function name='approach' return='float' arguments='float current, float goal, float speed'>
+		Use this to make a current value approach a goal value at the given speed.  Speed must not be negative.  The value will not overshoot the goal.<br />
+		Note:  When you see the error "approach: speed 1 is negative." it means that the speed value passed was negative.  The 1 is there because approach and multiapproach use the same internal function and can be ignored when using approach.
+	</Function>
 	<Function name='ArbitrarySpeedMods' theme='_fallback' return='LuaOptionRow' arguments=''>
 		[03 CustomSpeedMods.lua]
 	</Function>
@@ -136,7 +140,7 @@ save yourself some time, copy this for undocumented things:
 		[03 Gameplay.lua]
 	</Function>
 	<Function name='fapproach' theme='_fallback' return='float' arguments='float val, float other_val, float to_move'>
-		[02 Utilities.lua]
+		[02 Utilities.lua] Old name for approach.
 	</Function>
 	<Function name='FindSelection' theme='_fallback' return='int' arguments='table list'>
 		[02 Utilities.lua] Return the index of a true value in <code>list</code>.
@@ -327,6 +331,12 @@ save yourself some time, copy this for undocumented things:
 	<Function name='JudgmentLineToStrokeColor' theme='_fallback' return='color' arguments='JudgmentLine jl'>
 		[02 Colors.lua]
 	</Function>
+	<Function name='lerp' return='float' arguments='float percent, float start, float end'>
+		Returns a number linearly interpolated between start and end by percent.
+	</Function>
+	<Function name='lerp_color' return='color' arguments='float percent, color start, color end'>
+		Same as lerp, but for colors.  All channels will reach the end of the interpolation at the same time.
+	</Function>
 	<Function name='LoadActor' return='ActorDef' arguments='string sPath, ...'>
 		Returns an Actor definition for the actor at <code>sPath</code>. If <code>sPath</code> points to a Lua file, any additional arguments will be passed to that script.
 	</Function>
@@ -369,6 +379,11 @@ save yourself some time, copy this for undocumented things:
 	<Function name='MonthToString' return='string' arguments='Month m'>
 		Returns Month <code>m</code> as a string.
 	</Function>
+	<Function name='multiapproach' return='table' arguments='table currents, table goals, table speeds'>
+		Similar to approach, but operates on tables of values instead of single values.  This will modify the contents of <code>currents</code> in place, as well as returning <code>currents</code>.<br />
+		<code>currents</code>, <code>goals</code>, and <code>speeds</code> must all be the same size and contain only numbers.<br />
+		Note:  When you see the error "approach: speed 1 is negative." it means that a speed value passed was negative.  The 1 tells you which entry in the table was invalid.
+	</Function>
 	<Function name='next' return='void' arguments='table t, int index'>
 		"Allows a program to traverse all fields of a table. Its first argument is a
 		table and its second argument is an index in this table.
diff --git a/Themes/_fallback/Scripts/02 Utilities.lua b/Themes/_fallback/Scripts/02 Utilities.lua
index 4750c48b7d..53a3acf534 100644
--- a/Themes/_fallback/Scripts/02 Utilities.lua	
+++ b/Themes/_fallback/Scripts/02 Utilities.lua	
@@ -66,6 +66,8 @@ function wrap(val,n)
 end
 
 function fapproach(val, other_val, to_move)
+	-- This does not use the (faster) C++ side version of approach because I
+	-- don't want to find out how many themes pass a negative speed. -Kyz
 	if val == other_val then
 		return val -- already done!
 	end
diff --git a/src/LuaManager.h b/src/LuaManager.h
index 644780eb67..8573394ee4 100644
--- a/src/LuaManager.h
+++ b/src/LuaManager.h
@@ -266,6 +266,11 @@ void LuaFunc_Register_##func( lua_State *L ); \
 void LuaFunc_Register_##func( lua_State *L ) { lua_register( L, #func, LuaFunc_##func ); } \
 REGISTER_WITH_LUA_FUNCTION( LuaFunc_Register_##func );
 
+#define LUAFUNC_REGISTER_COMMON(func_name) \
+void LuaFunc_Register_##func_name(lua_State* L); \
+void LuaFunc_Register_##func_name(lua_State* L) { lua_register(L, #func_name, LuaFunc_##func_name); } \
+REGISTER_WITH_LUA_FUNCTION(LuaFunc_Register_##func_name);
+
 #endif
 
 /*
diff --git a/src/RageTypes.cpp b/src/RageTypes.cpp
index b3d96215a2..b554a042e7 100644
--- a/src/RageTypes.cpp
+++ b/src/RageTypes.cpp
@@ -74,6 +74,14 @@ RString RageColor::NormalizeColorString( RString sColor )
 	return c.ToString();
 }
 
+void lerp_rage_color(RageColor& out, RageColor const& a, RageColor const& b, float t)
+{
+	out.b= lerp(t, a.b, b.b);
+	out.g= lerp(t, a.g, b.g);
+	out.r= lerp(t, a.r, b.r);
+	out.a= lerp(t, a.a, b.a);
+}
+
 void WeightedAvergeOfRSVs(RageSpriteVertex& average_out, RageSpriteVertex const& rsv1, RageSpriteVertex const& rsv2, float percent_between)
 {
 	average_out.p= lerp(percent_between, rsv1.p, rsv2.p);
@@ -207,8 +215,21 @@ int LuaFunc_color( lua_State *L )
 	c.PushTable( L );
 	return 1;
 }
-void LuaFunc_Register_color( lua_State *L ) { lua_register( L, "color", LuaFunc_color ); }
-REGISTER_WITH_LUA_FUNCTION( LuaFunc_Register_color );
+LUAFUNC_REGISTER_COMMON(color);
+
+int LuaFunc_lerp_color(lua_State *L)
+{
+	// Args:  percent, color, color
+	// Returns:  color
+	float percent= FArg(1);
+	RageColor a, b, c;
+	a.FromStack(L, 2);
+	b.FromStack(L, 3);
+	lerp_rage_color(c, a, b, percent);
+	c.PushTable(L);
+	return 1;
+}
+LUAFUNC_REGISTER_COMMON(lerp_color);
 
 /*
  * Copyright (c) 2006 Glenn Maynard
diff --git a/src/RageTypes.h b/src/RageTypes.h
index 0a5d51a1c9..ddfc3e88ec 100644
--- a/src/RageTypes.h
+++ b/src/RageTypes.h
@@ -342,6 +342,7 @@ struct RageSpriteVertex	// has color
 	RageVector2 t; // texture coordinates
 };
 
+void lerp_rage_color(RageColor& out, RageColor const& a, RageColor const& b, float t);
 void WeightedAvergeOfRSVs(RageSpriteVertex& average_out, RageSpriteVertex const& rsv1, RageSpriteVertex const& rsv2, float percent_between);
 
 struct RageModelVertex	// doesn't have color.  Relies on material color
diff --git a/src/RageUtil.cpp b/src/RageUtil.cpp
index 8255f9e96d..c2d033f87e 100644
--- a/src/RageUtil.cpp
+++ b/src/RageUtil.cpp
@@ -2329,6 +2329,76 @@ LuaFunction( PrettyPercent, PrettyPercent( FArg(1), FArg(2) ) );
 //LuaFunction( IsHexVal, IsHexVal( SArg(1) ) );
 static bool UndocumentedFeature( RString s ){ sm_crash(s); return true; }
 LuaFunction( UndocumentedFeature, UndocumentedFeature(SArg(1)) );
+LuaFunction( lerp, lerp(FArg(1), FArg(2), FArg(3)) );
+
+void luafunc_approach_internal(lua_State* L, int valind, int goalind, int speedind);
+void luafunc_approach_internal(lua_State* L, int valind, int goalind, int speedind, int process_index)
+{
+#define TONUMBER_NICE(dest, num_name, index) \
+	if(!lua_isnumber(L, index)) \
+	{ \
+		luaL_error(L, "approach: " #num_name " for approach %d is not a number.", process_index); \
+	} \
+	dest= lua_tonumber(L, index);
+	float val= 0;
+	float goal= 0;
+	float speed= 0;
+	TONUMBER_NICE(val, current, valind);
+	TONUMBER_NICE(goal, goal, goalind);
+	TONUMBER_NICE(speed, speed, speedind);
+#undef TONUMBER_NICE
+	if(speed < 0)
+	{
+		luaL_error(L, "approach: speed %d is negative.", process_index);
+	}
+	fapproach(val, goal, speed);
+	lua_pushnumber(L, val);
+}
+
+int LuaFunc_approach(lua_State* L);
+int LuaFunc_approach(lua_State* L)
+{
+	// Args:  current, goal, speed
+	// Returns:  new_current
+	luafunc_approach_internal(L, 1, 2, 3, 1);
+	return 1;
+}
+LUAFUNC_REGISTER_COMMON(approach);
+
+int LuaFunc_multiapproach(lua_State* L);
+int LuaFunc_multiapproach(lua_State* L)
+{
+	// Args:  {currents}, {goals}, {speeds}
+	// Returns:  {currents}
+	// Modifies the values in {currents} in place.
+	if(lua_gettop(L) != 3)
+	{
+		luaL_error(L, "multiapproach:  A table of current values, a table of goal values, and a table of speeds must be passed.");
+	}
+	size_t currents_len= lua_objlen(L, 1);
+	size_t goals_len= lua_objlen(L, 2);
+	size_t speeds_len= lua_objlen(L, 3);
+	if(currents_len != goals_len || currents_len != speeds_len)
+	{
+		luaL_error(L, "multiapproach:  There must be the same number of current values, goal values, and speeds.");
+	}
+	if(!lua_istable(L, 1) || !lua_istable(L, 2) || !lua_istable(L, 3))
+	{
+		luaL_error(L, "multiapproach:  current, goal, and speed must all be tables.");
+	}
+	for(size_t i= 1; i <= currents_len; ++i)
+	{
+		lua_rawgeti(L, 1, i);
+		lua_rawgeti(L, 2, i);
+		lua_rawgeti(L, 3, i);
+		luafunc_approach_internal(L, -3, -2, -1, i);
+		lua_rawseti(L, 1, i);
+		lua_pop(L, 3);
+	}
+	lua_pushvalue(L, 1);
+	return 1;
+}
+LUAFUNC_REGISTER_COMMON(multiapproach);
 
 /*
  * Copyright (c) 2001-2005 Chris Danford, Glenn Maynard