Star wars is the only game to pass unsigned fixed shaded values (per vertex brightness) to the renderer. Originally we thought that the specular flag would turn on unsigned values since it's the only game to set specular with these polys, but this logic turned out to be incorrect. The JTAG interface seems to config the GPU to turn on this functionality. (Harry Tuttle)

Src/Graphics/IRender3D.h

@@ -19,6 +19,7 @@ public:
   virtual void SetStepping(int stepping) = 0;
   virtual bool Init(unsigned xOffset, unsigned yOffset, unsigned xRes, unsigned yRes, unsigned totalXRes, unsigned totalYRes) = 0;
   virtual void SetSunClamp(bool enable) = 0;
+  virtual void SetSignedShade(bool enable) = 0;
 
   virtual ~IRender3D()
   {

Src/Graphics/Legacy3D/Legacy3D.cpp

@@ -1301,6 +1301,10 @@ void CLegacy3D::SetSunClamp(bool enable)
 {
 }
 
+void CLegacy3D::SetSignedShade(bool enable)
+{
+}
+
 CLegacy3D::CLegacy3D(const Util::Config::Node &config)
   : m_config(config)
 { 

Src/Graphics/Legacy3D/Legacy3D.h

@@ -338,6 +338,16 @@ public:
 	*/
 	void SetSunClamp(bool enable);
 
+	/*
+	* SetSignedShade(bool enable);
+	*
+	* Sets the sign-ness of fixed shading value
+	*
+	* Parameters:
+	*		enable	Fixed shading is expressed as signed value
+	*/
+	void SetSignedShade(bool enable);
+
 	/*
 	 * CLegacy3D(void):
 	 * ~CLegacy3D(void):

Src/Graphics/New3D/New3D.cpp

@@ -25,6 +25,10 @@ CNew3D::CNew3D(const Util::Config::Node &config, std::string gameName)
 	m_vrom			= nullptr;
 	m_textureRAM	= nullptr;
 	m_sunClamp		= true;
+	m_shadeIsSigned = true;
+
+	// Fall-back mechanism for games with patched (not working) JTAG
+	if (m_gameName == "swtrilgy") m_shadeIsSigned = false;
 }
 
 CNew3D::~CNew3D()
@@ -1130,7 +1134,7 @@ void CNew3D::CacheModel(Model *m, const UINT32 *data)
 				float shade;
 				//==========
 
-				if (ph.SpecularEnabled()) {
+				if (!m_shadeIsSigned) {
 					shade = (ix & 0xFF) / 255.f;									// Star wars is the only game to use unsigned fixed shaded values. It's also the only game to set the specular flag on these polys
 				}
 				else {
@@ -1599,5 +1603,9 @@ void CNew3D::SetSunClamp(bool enable)
 	m_sunClamp = enable;
 }
 
-} // New3D
+void CNew3D::SetSignedShade(bool enable)
+{
+	m_shadeIsSigned = enable;
+}
 
+} // New3D

Src/Graphics/New3D/New3D.h

@@ -151,6 +151,16 @@ public:
 	*/
 	void SetSunClamp(bool enable);
 
+	/*
+	* SetSignedShade(bool enable);
+	*
+	* Sets the sign-ness of fixed shading value
+	*
+	* Parameters:
+	*		enable	Fixed shading is expressed as signed value
+	*/
+	void SetSignedShade(bool enable);
+
 	/*
 	* CRender3D(config):
 	* ~CRender3D(void):
@@ -203,7 +213,10 @@ private:
 
 	// Misc
 	std::string m_gameName;
+
+	// GPU configuration
 	bool m_sunClamp;
+	bool m_shadeIsSigned;
 
 	// Stepping
 	int		m_step;

Src/Model3/Real3D.cpp

@@ -153,7 +153,9 @@ void CReal3D::LoadState(CBlockFile *SaveState)
 static void UpdateRenderConfig(IRender3D *Render3D, uint64_t internalRenderConfig[])
 {
   bool noSunClamp = (internalRenderConfig[0] & 0x800000) != 0 && (internalRenderConfig[1] & 0x400000) != 0;
+  bool shadeIsSigned = (internalRenderConfig[0] & 0x1) == 0;
   Render3D->SetSunClamp(!noSunClamp);
+  Render3D->SetSignedShade(shadeIsSigned);
 }
 
 void CReal3D::BeginVBlank(int statusCycles)