Yes , you are right . At first , i only wan’t to know if gtk3 support display image use opengl, i think it’s easy, so i didn’t waste much time on opengl itself
In fact, the reason I use the old api glDrawPixels, glEnable and glLoadIdentity etc. , because most of the tutorials and example codes i searched is old and use glfw , maybe they think the old way is simple and friendly to opengl newbie to start study, it dosn’t need newbie to know shader which is complex.
Later, i test these codes successfully on glfw, so i thought GTK was the same way. In my cognition, i thought the difference of glfw and gtk is that one need call swapbuf api and another needn’t . Obviously , i was wrong.
Thank you again for your reply