when a 2nd player joins, remove double steps from the list. They're no longer playable with 2 players joined.

stepmania/src/CourseUtil.cpp

@@ -11,6 +11,7 @@
 #include "Foreach.h"
 #include "GameState.h"
 #include "LocalizedString.h"
+#include "LuaManager.h"
 
 
 //

stepmania/src/DifficultyList.cpp

@@ -247,13 +247,6 @@ void DifficultyList::SetFromGameState()
 {
 	const Song *pSong = GAMESTATE->m_pCurSong;
 
-	const bool bSongChanged = (pSong != m_CurSong);
-
-	/* If the song has changed, update displays: */
-	if( bSongChanged )
-	{
-		m_CurSong = pSong;
-
 	for( int m = 0; m < MAX_METERS; ++m )
 	{
 		m_Lines[m].m_Meter.Unset();
@@ -283,7 +276,7 @@ void DifficultyList::SetFromGameState()
 	else
 	{
 		vector<Steps*>	vpSteps;
-			SongUtil::GetPossibleSteps( pSong, vpSteps );
+		SongUtil::GetPlayableSteps( pSong, vpSteps );
 		/* Should match the sort in ScreenSelectMusic::AfterMusicChange. */
 
 		m_Rows.resize( vpSteps.size() );
@@ -298,17 +291,13 @@ void DifficultyList::SetFromGameState()
 			row.m_dc = row.m_Steps->GetDifficulty();
 		}
 	}
-	}
 
 	UpdatePositions();
 	PositionItems();
 
-	if( bSongChanged )
-	{
 	for( int m = 0; m < MAX_METERS; ++m )
 		m_Lines[m].m_Meter.FinishTweening();
 }
-}
 
 void DifficultyList::HideRows()
 {

stepmania/src/GameManager.cpp

@@ -2340,21 +2340,23 @@ void GameManager::GetCompatibleStyles( const Game *pGame, int iNumPlayers, vecto
 {
 	FOREACH_ENUM( StyleType, styleType )
 	{
+		int iNumPlayersRequired;
 		switch( styleType )
 		{
 		DEFAULT_FAIL( styleType );
 		case StyleType_OnePlayerOneSide:
 		case StyleType_OnePlayerTwoSides:
-			if( iNumPlayers != 1 )
+			iNumPlayersRequired = 1;
-				continue;
 			break;
 		case StyleType_TwoPlayersTwoSides:
 		case StyleType_TwoPlayersSharedSides:
-			if( iNumPlayers != 2 )
+			iNumPlayersRequired = 2;
-				continue;
 			break;
 		}
 
+		if( iNumPlayers != iNumPlayersRequired )
+			continue;
+
 		for( unsigned s=0; s<NUM_STYLES; s++ ) 
 		{
 			const Style* style = &g_Styles[s];

stepmania/src/MusicWheel.cpp

@@ -170,7 +170,7 @@ void MusicWheel::BeginScreen()
 		if( GAMESTATE->m_pCurSteps[p] != NULL )
 		{
 			vector<Steps*> vpPossibleSteps;
-			SongUtil::GetPossibleSteps( GAMESTATE->m_pCurSong, vpPossibleSteps );
+			SongUtil::GetPlayableSteps( GAMESTATE->m_pCurSong, vpPossibleSteps );
 			bool bStepsIsPossible = find( vpPossibleSteps.begin(), vpPossibleSteps.end(), GAMESTATE->m_pCurSteps[p] ) == vpPossibleSteps.end();
 			if( !bStepsIsPossible )
 				GAMESTATE->m_pCurSteps[p].Set( NULL );

stepmania/src/ScreenSelectMusic.cpp

@@ -298,6 +298,9 @@ void ScreenSelectMusic::Input( const InputEventPlus &input )
 	// Handle late joining
 	if( input.MenuI == MENU_BUTTON_START  &&  input.type == IET_FIRST_PRESS  &&  GAMESTATE->JoinInput(input.pn) )
 	{
+		// refresh the steps list so that 2-side StepsTypes will be removed since they're no longer playable
+		AfterMusicChange();
+
 		int iSel = 0;
 		PlayerNumber pn = input.pn;
 		m_iSelection[pn] = iSel;
@@ -311,6 +314,7 @@ void ScreenSelectMusic::Input( const InputEventPlus &input )
 			Steps* pSteps = m_vpSteps.empty()? NULL: m_vpSteps[m_iSelection[pn]];
 			GAMESTATE->m_pCurSteps[pn].Set( pSteps );
 		}
+
 		return;	// don't handle this press again below
 	}
 
@@ -1058,7 +1062,7 @@ void ScreenSelectMusic::AfterMusicChange()
 		m_fSampleStartSeconds = pSong->m_fMusicSampleStartSeconds;
 		m_fSampleLengthSeconds = pSong->m_fMusicSampleLengthSeconds;
 
-		SongUtil::GetPossibleSteps( pSong, m_vpSteps );
+		SongUtil::GetPlayableSteps( pSong, m_vpSteps );
 
 		if ( PREFSMAN->m_bShowBanners )
 			g_sBannerPath = pSong->GetBannerPath();

stepmania/src/SongUtil.cpp

@@ -16,6 +16,8 @@
 #include "RageLog.h"
 #include "GameManager.h"
 #include "CommonMetrics.h"
+#include "LuaBinding.h"
+#include "EnumHelper.h"
 
 bool SongCriteria::Matches( const Song *pSong ) const
 {
@@ -810,30 +812,35 @@ void SongUtil::FilterSongs( const SongCriteria &sc, const vector<Song*> &in, vec
 	}
 }
 
-void SongUtil::GetPossibleSteps( const Song *pSong, vector<Steps*> &vOut )
+static void GetPlayableStepsTypes( set<StepsType> &vOut )
 {
 	vector<const Style*> vpPossibleStyles;
 	if( CommonMetrics::ALL_STEPS_TYPES_IN_ONE_LIST )
 		GAMEMAN->GetCompatibleStyles( GAMESTATE->m_pCurGame, GAMESTATE->GetNumPlayersEnabled(), vpPossibleStyles );
 	else
 		vpPossibleStyles.push_back( GAMESTATE->m_pCurStyle );
-	set<StepsType> vStepsType;
 	FOREACH( const Style*, vpPossibleStyles, s )
-		vStepsType.insert( (*s)->m_StepsType );
+		vOut.insert( (*s)->m_StepsType );
 
 	// filter out hidden StepsTypes
 	const vector<StepsType> &vstToShow = CommonMetrics::STEPS_TYPES_TO_SHOW.GetValue();
-	FOREACHS( StepsType, vStepsType, st )
+	FOREACHS( StepsType, vOut, st )
 	{
 		bool bShowThis = find( vstToShow.begin(), vstToShow.end(), *st ) != vstToShow.end();
 		if( !bShowThis )
 		{
 			set<StepsType>::iterator to_erase = st;
 			++st;
-			vStepsType.erase( to_erase );
+			vOut.erase( to_erase );
 			--st;
 		}
 	}
+}
+
+void SongUtil::GetPlayableSteps( const Song *pSong, vector<Steps*> &vOut )
+{
+	set<StepsType> vStepsType;
+	GetPlayableStepsTypes( vStepsType );
 
 	FOREACHS( StepsType, vStepsType, st )
 		SongUtil::GetSteps( pSong, vOut, *st );
@@ -853,6 +860,13 @@ void SongUtil::GetPossibleSteps( const Song *pSong, vector<Steps*> &vOut )
 	}
 }
 
+bool SongUtil::IsStepsTypePlayable( StepsType st  )
+{
+	set<StepsType> vStepsType;
+	GetPlayableStepsTypes( vStepsType );
+	return vStepsType.find( st ) != vStepsType.end();
+}
+
 //////////////////////////////////
 // SongID
 //////////////////////////////////
@@ -906,6 +920,29 @@ bool SongID::IsValid() const
 	return !sDir.empty();
 }
 
+// lua start
+#include "LuaBinding.h"
+
+namespace
+{
+	int IsStepsTypePlayable( lua_State *L )
+	{
+		StepsType st = Enum::Check<StepsType>(L, 1);
+		bool b = SongUtil::IsStepsTypePlayable( st );
+		LuaHelpers::Push( L, b );
+		return 1;
+	}
+
+	const luaL_Reg SongUtilTable[] =
+	{
+		LIST_METHOD( IsStepsTypePlayable ),
+		{ NULL, NULL }
+	};
+}
+
+LUA_REGISTER_NAMESPACE( SongUtil )
+
+
 /*
  * (c) 2001-2004 Chris Danford, Glenn Maynard
  * All rights reserved.

stepmania/src/SongUtil.h

@@ -110,7 +110,8 @@ namespace SongUtil
 	void GetAllSongGenres( vector<RString> &vsOut );
 	void FilterSongs( const SongCriteria &sc, const vector<Song*> &in, vector<Song*> &out );
 
-	void GetPossibleSteps( const Song *pSong, vector<Steps*> &vOut );
+	void GetPlayableSteps( const Song *pSong, vector<Steps*> &vOut );
+	bool IsStepsTypePlayable( StepsType st );
 }
 
 class SongID