I don’t really need 3D stuffs and GLSL. I just need to draw few simple lines, circles, rectangles etc.
so is it good idea to stick with OpenGL 1.1? Is there disadvantages over using Legacy OpenGL?
Will OpenGL 1.1 not supported in the future? For example, does Microsoft planning to remove OpenGL 1.1?
Well, 1.1 is the only version Windows supports directly. Anything later version is an extension provided by the driver.
Realistically, the only way that 1.1 won’t be supported is if they stop supporting OpenGL altogether. In turn, that would result in a lot of existing software not working (e.g. all of ID Software’s later games used OpenGL), so it’s not likely to happen.
You’re making the classic mistake of thinking that OpenGL versions beyond 1.1 just add “fancy stuff”. That’s not the case at all. What higher versions add is more efficient and more flexible ways of drawing, that are more likely to be hardware-accelerated than a lot of the older 1.1 functionality.
If you search through the forums you’ll see that there’s a lot of questions along the lines of “why is my simple program that does simple drawing with simple code bringing the latest 3D card to it’s knees?” and the answer is invariably that the OP is using OpenGL 1.1 with immediate mode and not much knowledge of how to organize a workload so that it plays nicer with the way hardware likes to recieve it.