milek7/sim branch opengl 3.3 renderer import

gl/bindable.h

@@ -0,0 +1,27 @@
+#pragma once
+
+namespace gl
+{
+    template <typename T>
+    class bindable
+    {
+    protected:
+		thread_local static bindable<T>* active;
+
+    public:
+        void bind()
+        {
+            if (active == this)
+                return;
+            active = this;
+            T::bind(*static_cast<T*>(active));
+        }
+        static void unbind()
+        {
+            active = nullptr;
+            T::bind(0);
+        }
+    };
+
+	template <typename T> thread_local bindable<T>* bindable<T>::active;
+}