gsdx-ogl: add texure clear function (GL4.4)

plugins/GSdx/GLLoader.cpp

@@ -115,6 +115,7 @@ PFNGLBINDIMAGETEXTUREPROC              glBindImageTexture                  = NUL
 PFNGLMEMORYBARRIERPROC                 glMemoryBarrier                     = NULL;
 // GL4.4
 PFNGLCLEARTEXIMAGEPROC                 glClearTexImage                     = NULL;
+PFNGLCLEARTEXSUBIMAGEPROC              glClearTexSubImage                  = NULL;
 PFNGLBUFFERSTORAGEPROC                 glBufferStorage                     = NULL;
 
 // GL4.5

plugins/GSdx/GLLoader.h

@@ -290,6 +290,7 @@ extern   PFNGLDEBUGMESSAGEINSERTPROC            glDebugMessageInsert;
 extern   PFNGLDEBUGMESSAGECONTROLPROC           glDebugMessageControl;
 // GL4.4
 extern   PFNGLCLEARTEXIMAGEPROC                 glClearTexImage;
+extern   PFNGLCLEARTEXSUBIMAGEPROC              glClearTexSubImage;
 extern   PFNGLBUFFERSTORAGEPROC                 glBufferStorage;
 
 // GL4.5

plugins/GSdx/GSTextureOGL.cpp

@@ -223,10 +223,15 @@ GSTextureOGL::GSTextureOGL(int type, int w, int h, int format, GLuint fbo_read)
 			m_int_shift     = 3;
 			break;
 
-			// Special
-		case 0:
+			// Depth buffer
 		case GL_DEPTH32F_STENCIL8:
-			// Backbuffer & dss aren't important
+			m_int_format    = GL_DEPTH_STENCIL;
+			m_int_type      = GL_FLOAT_32_UNSIGNED_INT_24_8_REV;
+			m_int_shift     = 0;
+			break;
+
+			// Backbuffer
+		case 0:
 			m_int_format    = 0;
 			m_int_type      = 0;
 			m_int_shift     = 0;
@@ -281,6 +286,16 @@ GSTextureOGL::~GSTextureOGL()
 		_aligned_free(m_local_buffer);
 }
 
+void GSTextureOGL::Clear(const void* data)
+{
+	glClearTexImage(m_texture_id, GL_TEX_LEVEL_0, m_int_format, m_int_type, data);
+}
+
+void GSTextureOGL::Clear(const void* data, const GSVector4i& area)
+{
+	glClearTexSubImage(m_texture_id, area.x, area.y, 0, area.width(), area.height(), 1, GL_TEX_LEVEL_0, m_int_format, m_int_type, data);
+}
+
 bool GSTextureOGL::Update(const GSVector4i& r, const void* data, int pitch)
 {
 	ASSERT(m_type != GSTexture::DepthStencil && m_type != GSTexture::Offscreen);

plugins/GSdx/GSTextureOGL.h

@@ -77,5 +77,8 @@ class GSTextureOGL final : public GSTexture
 		void WasAttached() { m_clean = false; }
 		void WasCleaned() { m_clean = true; }
 
+		void Clear(const void* data);
+		void Clear(const void* data, const GSVector4i& area);
+
 		uint32 GetMemUsage();
 };

plugins/GSdx/GSWnd.cpp

@@ -124,6 +124,7 @@ void GSWndGL::PopulateGlFunction()
 	GL_EXT_LOAD(glDebugMessageCallback);
 	// GL4.4
 	GL_EXT_LOAD_OPT(glClearTexImage);
+	GL_EXT_LOAD_OPT(glClearTexSubImage);
 	GL_EXT_LOAD(glBufferStorage);
 
 	// GL4.5