Make VAO binding into a dedicated function.

It's used from more than one place.

src/Magnum/Buffer.cpp

@@ -283,13 +283,8 @@ auto Buffer::bindSomewhereInternal(const TargetHint hint) -> TargetHint {
         auto& currentVAO = Context::current().state().mesh->currentVAO;
         /* It can be also State::DisengagedBinding, in which case we unbind as
            well to be sure */
-        if(currentVAO != 0) {
-            #ifndef MAGNUM_TARGET_GLES2
-            glBindVertexArray(currentVAO = 0);
-            #else
-            glBindVertexArrayOES(currentVAO = 0);
-            #endif
-        }
+        if(currentVAO != 0)
+            Context::current().state().mesh->bindVAOImplementation(0);
     }
 
     /* Bind the buffer to hint target otherwise */

src/Magnum/Implementation/MeshState.cpp

@@ -68,6 +68,7 @@ MeshState::MeshState(Context& context, ContextState& contextState, std::vector<s
         }
 
         bindIndexBufferImplementation = &Mesh::bindIndexBufferImplementationVAO;
+        bindVAOImplementation = &Mesh::bindVAOImplementationVAO;
         bindImplementation = &Mesh::bindImplementationVAO;
         unbindImplementation = &Mesh::unbindImplementationVAO;
     }
@@ -77,6 +78,7 @@ MeshState::MeshState(Context& context, ContextState& contextState, std::vector<s
         destroyImplementation = &Mesh::destroyImplementationDefault;
         attributePointerImplementation = &Mesh::attributePointerImplementationDefault;
         bindIndexBufferImplementation = &Mesh::bindIndexBufferImplementationDefault;
+        bindVAOImplementation = &Mesh::bindVAOImplementationDefault;
         bindImplementation = &Mesh::bindImplementationDefault;
         unbindImplementation = &Mesh::unbindImplementationDefault;
     }

src/Magnum/Implementation/MeshState.h

@@ -59,6 +59,8 @@ struct MeshState {
     void(*multiDrawImplementation)(std::initializer_list<std::reference_wrapper<MeshView>>);
     #endif
 
+    void(*bindVAOImplementation)(GLuint);
+
     #ifndef MAGNUM_TARGET_GLES
     GLuint defaultVAO{}; /* Used on core profile in case ARB_VAO is disabled */
     #endif

src/Magnum/Mesh.cpp

@@ -418,16 +418,23 @@ void Mesh::draw(AbstractShaderProgram& shader, TransformFeedback& xfb, UnsignedI
 }
 #endif
 
+void Mesh::bindVAOImplementationDefault(GLuint) {}
+
+void Mesh::bindVAOImplementationVAO(const GLuint id) {
+    #ifndef MAGNUM_TARGET_GLES2
+    glBindVertexArray
+    #else
+    glBindVertexArrayOES
+    #endif
+        (Context::current().state().mesh->currentVAO = id);
+}
+
 void Mesh::bindVAO() {
     GLuint& current = Context::current().state().mesh->currentVAO;
     if(current != _id) {
         /* Binding the VAO finally creates it */
         _flags |= ObjectFlag::Created;
-        #ifndef MAGNUM_TARGET_GLES2
-        glBindVertexArray(current = _id);
-        #else
-        glBindVertexArrayOES(current = _id);
-        #endif
+        bindVAOImplementationVAO(_id);
     }
 }
 

src/Magnum/Mesh.h

@@ -1043,6 +1043,11 @@ class MAGNUM_EXPORT Mesh: public AbstractObject {
         #endif
         #endif
 
+        /* Unconditionally binds a specified VAO and updates the state tracker.
+           Used also in Buffer::bindSomewhereInternal(). */
+        static void MAGNUM_LOCAL bindVAOImplementationDefault(GLuint id);
+        static void MAGNUM_LOCAL bindVAOImplementationVAO(GLuint id);
+
         void MAGNUM_LOCAL bindVAO();
 
         #ifndef MAGNUM_TARGET_GLES