GL: Fixed initial value of binary shader hash.

src/renderer_gl.cpp

@@ -2004,13 +2004,25 @@ namespace bgfx
 		s_renderCtx.flip();
 	}
 
-	GLint glGet(GLenum _pname)
+	static GLint glGet(GLenum _pname)
 	{
 		GLint result;
 		GL_CHECK(glGetIntegerv(_pname, &result) );
 		return result;
 	}
 
+	static uint32_t glGetStringHash(GLenum _name)
+	{
+		const char* str = (const char*)glGetString(_name);
+		glGetError(); // ignore error if glGetString returns NULL.
+		if (NULL != str)
+		{
+			return bx::hashMurmur2A(str, strlen(str) );
+		}
+
+		return 0;
+	}
+
 	void Context::rendererInit()
 	{
 		s_renderCtx.init();
@@ -2056,6 +2068,13 @@ namespace bgfx
 		BX_TRACE("GLSL version: %s", version);
 #endif // BGFX_CONFIG_DEBUG
 
+		// Initial binary shader hash depends on driver version.
+		s_renderCtx.m_hash = ( (BX_PLATFORM_WINDOWS<<1) | BX_ARCH_64BIT)
+						^ (uint64_t(glGetStringHash(GL_VENDOR  ) )<<32)
+						^ (uint64_t(glGetStringHash(GL_RENDERER) )<<0 )
+						^ (uint64_t(glGetStringHash(GL_VERSION ) )<<16)
+						;
+
 		const char* extensions = (const char*)glGetString(GL_EXTENSIONS);
 		glGetError(); // ignore error if glGetString returns NULL.
 		if (NULL != extensions)