Not sure we can provide much help here. You probably want to post this in SDL2 or GL generic forums. Our IntegrationGLUT sample is very clear about GL usage.

OK, thanks for your reply~

Here's my code about Noesis GUI: NOTICE: GLRenderDevice's code is from NoesisApp framwork. #include <assert.h> #include <glad.h> #include <Noesis_pch.h> #include "local_xml_provider.h" #include "Render/OpenGL/render_device_openGL.h" using namespace Noesis; Ptr<IView> view; void N...

Currently working on a game mod with HL1 SDK,
I'v been thinking for about a week but just can't figure out how to do that,
please help me