OGL: Support Quad-Buffered stereoscopy.

Source/Core/Common/GL/GLInterface/AGL.h

@@ -17,7 +17,7 @@ class cInterfaceAGL : public cInterfaceBase
 {
 public:
   void Swap() override;
-  bool Create(void* window_handle, bool core) override;
+  bool Create(void* window_handle, bool stereo, bool core) override;
   bool MakeCurrent() override;
   bool ClearCurrent() override;
   void Shutdown() override;

Source/Core/Common/GL/GLInterface/AGL.mm

@@ -51,12 +51,15 @@ void cInterfaceAGL::Swap()
 
 // Create rendering window.
 // Call browser: Core.cpp:EmuThread() > main.cpp:Video_Initialize()
-bool cInterfaceAGL::Create(void* window_handle, bool core)
+bool cInterfaceAGL::Create(void* window_handle, bool stereo, bool core)
 {
-  NSOpenGLPixelFormatAttribute attr[] = {NSOpenGLPFADoubleBuffer, NSOpenGLPFAOpenGLProfile,
+  NSOpenGLPixelFormatAttribute attr[] = {
-                                         core ? NSOpenGLProfileVersion3_2Core :
+      NSOpenGLPFADoubleBuffer,
-                                                NSOpenGLProfileVersionLegacy,
+      NSOpenGLPFAOpenGLProfile,
-                                         NSOpenGLPFAAccelerated, 0};
+      core ? NSOpenGLProfileVersion3_2Core : NSOpenGLProfileVersionLegacy,
+      NSOpenGLPFAAccelerated,
+      stereo ? NSOpenGLPFAStereo : static_cast<NSOpenGLPixelFormatAttribute>(0),
+      0};
   NSOpenGLPixelFormat* fmt = [[NSOpenGLPixelFormat alloc] initWithAttributes:attr];
   if (fmt == nil)
   {

Source/Core/Common/GL/GLInterface/BGL.cpp

@@ -13,7 +13,7 @@ void cInterfaceBGL::Swap()
   m_gl->SwapBuffers();
 }
 
-bool cInterfaceBGL::Create(void* window_handle, bool core)
+bool cInterfaceBGL::Create(void* window_handle, bool stereo, bool core)
 {
   m_window = static_cast<BWindow*>(window_handle);
 

Source/Core/Common/GL/GLInterface/BGL.h

@@ -14,7 +14,7 @@ class cInterfaceBGL final : public cInterfaceBase
 public:
   void Swap() override;
   void* GetFuncAddress(const std::string& name) override;
-  bool Create(void* window_handle, bool core) override;
+  bool Create(void* window_handle, bool stereo, bool core) override;
   bool MakeCurrent() override;
   bool ClearCurrent() override;
   void Shutdown() override;

Source/Core/Common/GL/GLInterface/EGL.cpp

@@ -111,7 +111,7 @@ void cInterfaceEGL::DetectMode()
 
 // Create rendering window.
 // Call browser: Core.cpp:EmuThread() > main.cpp:Video_Initialize()
-bool cInterfaceEGL::Create(void* window_handle, bool core)
+bool cInterfaceEGL::Create(void* window_handle, bool stereo, bool core)
 {
   EGLint egl_major, egl_minor;
   bool supports_core_profile = false;

Source/Core/Common/GL/GLInterface/EGL.h

@@ -38,7 +38,7 @@ public:
   void SwapInterval(int interval) override;
   void SetMode(GLInterfaceMode mode) override { s_opengl_mode = mode; }
   void* GetFuncAddress(const std::string& name) override;
-  bool Create(void* window_handle, bool core) override;
+  bool Create(void* window_handle, bool stereo, bool core) override;
   bool Create(cInterfaceBase* main_context) override;
   bool MakeCurrent() override;
   bool ClearCurrent() override;

Source/Core/Common/GL/GLInterface/GLX.cpp

@@ -43,7 +43,7 @@ void cInterfaceGLX::Swap()
 
 // Create rendering window.
 // Call browser: Core.cpp:EmuThread() > main.cpp:Video_Initialize()
-bool cInterfaceGLX::Create(void* window_handle, bool core)
+bool cInterfaceGLX::Create(void* window_handle, bool stereo, bool core)
 {
   dpy = XOpenDisplay(nullptr);
   int screen = DefaultScreen(dpy);
@@ -87,6 +87,8 @@ bool cInterfaceGLX::Create(void* window_handle, bool core)
                           0,
                           GLX_DOUBLEBUFFER,
                           True,
+                          GLX_STEREO,
+                          stereo ? True : False,
                           None};
   int fbcount = 0;
   GLXFBConfig* fbc = glXChooseFBConfig(dpy, screen, visual_attribs, &fbcount);

Source/Core/Common/GL/GLInterface/GLX.h

@@ -24,7 +24,7 @@ public:
   void SwapInterval(int Interval) override;
   void Swap() override;
   void* GetFuncAddress(const std::string& name) override;
-  bool Create(void* window_handle, bool core) override;
+  bool Create(void* window_handle, bool stereo, bool core) override;
   bool MakeCurrent() override;
   bool ClearCurrent() override;
   void Shutdown() override;

Source/Core/Common/GL/GLInterface/WGL.cpp

@@ -200,7 +200,7 @@ bool cInterfaceWGL::PeekMessages()
 
 // Create rendering window.
 // Call browser: Core.cpp:EmuThread() > main.cpp:Video_Initialize()
-bool cInterfaceWGL::Create(void* window_handle, bool core)
+bool cInterfaceWGL::Create(void* window_handle, bool stereo, bool core)
 {
   if (!window_handle)
     return false;
@@ -219,12 +219,14 @@ bool cInterfaceWGL::Create(void* window_handle, bool core)
   s_backbuffer_width = twidth;
   s_backbuffer_height = theight;
 
-  static constexpr PIXELFORMATDESCRIPTOR pfd = {
+  const DWORD stereo_flag = stereo ? PFD_STEREO : 0;
+  static const PIXELFORMATDESCRIPTOR pfd = {
       sizeof(PIXELFORMATDESCRIPTOR),  // Size Of This Pixel Format Descriptor
       1,                              // Version Number
       PFD_DRAW_TO_WINDOW |            // Format Must Support Window
           PFD_SUPPORT_OPENGL |        // Format Must Support OpenGL
-          PFD_DOUBLEBUFFER,           // Must Support Double Buffering
+          PFD_DOUBLEBUFFER |          // Must Support Double Buffering
+          stereo_flag,                // Could Support Quad Buffering
       PFD_TYPE_RGBA,                  // Request An RGBA Format
       32,                             // Select Our Color Depth
       0,

Source/Core/Common/GL/GLInterface/WGL.h

@@ -14,7 +14,7 @@ public:
   void SwapInterval(int interval) override;
   void Swap() override;
   void* GetFuncAddress(const std::string& name) override;
-  bool Create(void* window_handle, bool core) override;
+  bool Create(void* window_handle, bool stereo, bool core) override;
   bool Create(cInterfaceBase* main_context) override;
   bool MakeCurrent() override;
   bool ClearCurrent() override;

Source/Core/Common/GL/GLInterfaceBase.h

@@ -34,7 +34,7 @@ public:
   virtual void SetMode(GLInterfaceMode mode) { s_opengl_mode = GLInterfaceMode::MODE_OPENGL; }
   virtual GLInterfaceMode GetMode() { return s_opengl_mode; }
   virtual void* GetFuncAddress(const std::string& name) { return nullptr; }
-  virtual bool Create(void* window_handle, bool core = true) { return true; }
+  virtual bool Create(void* window_handle, bool stereo = false, bool core = true) { return true; }
   virtual bool Create(cInterfaceBase* main_context) { return true; }
   virtual bool MakeCurrent() { return true; }
   virtual bool ClearCurrent() { return true; }

Source/Core/VideoBackends/OGL/Render.cpp

@@ -1196,6 +1196,16 @@ void Renderer::BlitScreen(TargetRectangle src, TargetRectangle dst, GLuint src_t
     post_processor->BlitFromTexture(src, leftRc, src_texture, src_width, src_height, 0);
     post_processor->BlitFromTexture(src, rightRc, src_texture, src_width, src_height, 1);
   }
+  else if (g_ActiveConfig.iStereoMode == STEREO_QUADBUFFER)
+  {
+    glDrawBuffer(GL_BACK_LEFT);
+    post_processor->BlitFromTexture(src, dst, src_texture, src_width, src_height, 0);
+
+    glDrawBuffer(GL_BACK_RIGHT);
+    post_processor->BlitFromTexture(src, dst, src_texture, src_width, src_height, 1);
+
+    glDrawBuffer(GL_BACK);
+  }
   else
   {
     post_processor->BlitFromTexture(src, dst, src_texture, src_width, src_height, 0);

Source/Core/VideoBackends/OGL/main.cpp

@@ -167,7 +167,7 @@ bool VideoBackend::Initialize(void* window_handle)
 
   InitInterface();
   GLInterface->SetMode(GLInterfaceMode::MODE_DETECT);
-  if (!GLInterface->Create(window_handle))
+  if (!GLInterface->Create(window_handle, g_ActiveConfig.iStereoMode == STEREO_QUADBUFFER))
     return false;
 
   return true;