floating-point zbias. For compatibility, 0 is off and 1 is the old "zbias on".

Going beyond 1 is allowed, but the usable/useful range of values is currently
undefined--try to stick to 0..1.

stepmania/src/Actor.cpp

@@ -76,7 +76,7 @@ void Actor::Reset()
 
 	m_bTextureWrapping = false;
 	m_BlendMode = BLEND_NORMAL;
-	m_bZBias = false;
+	m_fZBias = 0;
 	m_bClearZBuffer = false;
 	m_ZTestMode = ZTEST_OFF;
 	m_bZWrite = false;
@@ -389,7 +389,10 @@ void Actor::SetGlobalRenderStates()
 	
 	// BLEND_NO_EFFECT is used to draw masks to the Z-buffer, which always wants
 	// Z-bias enabled.
-	DISPLAY->SetZBias( m_bZBias || m_BlendMode == BLEND_NO_EFFECT );
+	if( m_fZBias == 0 && m_BlendMode == BLEND_NO_EFFECT )
+		DISPLAY->SetZBias( 1.0f );
+	else
+		DISPLAY->SetZBias( m_fZBias );
 
 	if( m_bClearZBuffer )
 		DISPLAY->ClearZBuffer();

stepmania/src/Actor.h

@@ -342,7 +342,7 @@ public:
 	virtual void SetZTestMode( ZTestMode mode ) { m_ZTestMode = mode; } 
 	void SetZTestModeString( const CString &s );	// convenience
 	virtual void SetZWrite( bool b ) 			{ m_bZWrite = b; } 
-	void SetZBias( bool b )						{ m_bZBias = b; }
+	void SetZBias( float f )					{ m_fZBias = f; }
 	virtual void SetCullMode( CullMode mode ) 	{ m_CullMode = mode; } 
 	void SetCullModeString( const CString &s );	// convenience
 
@@ -464,7 +464,7 @@ protected:
 	bool		m_bClearZBuffer;
 	ZTestMode	m_ZTestMode;
 	bool		m_bZWrite;
-	bool		m_bZBias; // if true, always wins z-test against a coplanar actor
+	float		m_fZBias; // 0 = no bias; 1 = full bias
 	CullMode	m_CullMode;
 
 	//
@@ -578,7 +578,7 @@ public:
 	static int ztest( T* p, lua_State *L )				{ p->SetZTestMode((!!IArg(1))?ZTEST_WRITE_ON_PASS:ZTEST_OFF); return 0; }
 	static int ztestmode( T* p, lua_State *L )			{ p->SetZTestModeString(SArg(1)); return 0; }
 	static int zwrite( T* p, lua_State *L )				{ p->SetZWrite(!!IArg(1)); return 0; }
-	static int zbias( T* p, lua_State *L )				{ p->SetZBias(!!IArg(1)); return 0; }
+	static int zbias( T* p, lua_State *L )				{ p->SetZBias(FArg(1)); return 0; }
 	static int clearzbuffer( T* p, lua_State *L )		{ p->SetClearZBuffer(!!IArg(1)); return 0; }
 	static int backfacecull( T* p, lua_State *L )		{ p->SetCullMode((!!IArg(1)) ? CULL_BACK : CULL_NONE); return 0; }
 	static int cullmode( T* p, lua_State *L )			{ p->SetCullModeString(SArg(1)); return 0; }

stepmania/src/RageDisplay.h

@@ -172,7 +172,7 @@ public:
 	virtual bool IsZWriteEnabled() const = 0;
 	virtual void SetZWrite( bool b ) = 0;
 	virtual void SetZTestMode( ZTestMode mode ) = 0;
-	virtual void SetZBias( bool b ) = 0;
+	virtual void SetZBias( float f ) = 0;
 	virtual void ClearZBuffer() = 0;
 
 	virtual void SetCullMode( CullMode mode ) = 0;

stepmania/src/RageDisplay_D3D.cpp

@@ -1061,12 +1061,9 @@ bool RageDisplay_D3D::IsZWriteEnabled() const
 	return b!=0;
 }
 
-void RageDisplay_D3D::SetZBias( bool b )
+void RageDisplay_D3D::SetZBias( float f )
 {
-	if( b )
-		g_pd3dDevice->SetRenderState( D3DRS_ZBIAS, 30 );
-	else
-		g_pd3dDevice->SetRenderState( D3DRS_ZBIAS, 0 );
+	g_pd3dDevice->SetRenderState( D3DRS_ZBIAS, (int) SCALE( f, 0.0f, 1.0f, 0, 30 ) );
 }
 
 

stepmania/src/RageDisplay_D3D.h

@@ -41,7 +41,7 @@ public:
 	bool IsZWriteEnabled() const;
 	bool IsZTestEnabled() const;
 	void SetZWrite( bool b );
-	void SetZBias( bool b );
+	void SetZBias( float f );
 	void SetZTestMode( ZTestMode mode );
 	void ClearZBuffer();
 	void SetCullMode( CullMode mode );

stepmania/src/RageDisplay_Null.h

@@ -39,7 +39,7 @@ public:
 	bool IsZWriteEnabled() const { return false; }
 	bool IsZTestEnabled() const { return false; }
 	void SetZWrite( bool b ) { }
-	void SetZBias( bool b ) { }
+	void SetZBias( float f ) { }
 	void SetZTestMode( ZTestMode mode ) { }
 	void ClearZBuffer() { }
 	void SetCullMode( CullMode mode ) { }

stepmania/src/RageDisplay_OGL.cpp

@@ -1517,12 +1517,12 @@ void RageDisplay_OGL::SetZWrite( bool b )
 	glDepthMask( b );
 }
 
-void RageDisplay_OGL::SetZBias( bool b )
+void RageDisplay_OGL::SetZBias( float f )
 {
-	if( b )
-		glDepthRange( 0.0, 0.95 );
-	else 
-		glDepthRange( 0.05, 1.0 );
+	float fNear = SCALE( f, 0.0f, 1.0f, 0.05f, 0.0f );
+	float fFar = SCALE( f, 0.0f, 1.0f, 1.0f, 0.95f );
+
+	glDepthRange( fNear, fFar );
 }
 
 void RageDisplay_OGL::SetZTestMode( ZTestMode mode )

stepmania/src/RageDisplay_OGL.h

@@ -42,7 +42,7 @@ public:
 	bool IsZWriteEnabled() const;
 	bool IsZTestEnabled() const;
 	void SetZWrite( bool b );
-	void SetZBias( bool b );
+	void SetZBias( float f );
 	void SetZTestMode( ZTestMode mode );
 	void ClearZBuffer();
 	void SetCullMode( CullMode mode );