Pits encountered by sdl2 OpenGL

Novice use SDL2 It's time to create SDL_Renderer Renderers

Default SDL2 Renderer It seems to be used D3D（ I'm not sure ）

The corresponding display function is SDL_RenderPresent()

Then we opengl The corresponding display function is SDL_GL_SwapWindow()

After testing , The above two functions can display normally , But it can't be used together , Otherwise, it will flash

pit 1：SDL_RenderClear Use of functions

use SDL It's no problem to call the cleanup function when the default renderer

Use opengl Calling this later will erase the screen , Careful use

Reference link

How to be in SDL2 Use in opengl

Start with initialization

//  Set up  SQL  Version and information 
SDL_GL_SetAttribute(SDL_GL_CONTEXT_MAJOR_VERSION, 3);
SDL_GL_SetAttribute(SDL_GL_CONTEXT_MINOR_VERSION, 3);
SDL_GL_SetAttribute(SDL_GL_DEPTH_SIZE, 24);
SDL_GL_SetAttribute(SDL_GL_CONTEXT_PROFILE_MASK, SDL_GL_CONTEXT_PROFILE_CORE);

And then in your SDL_CreateWindow Add the SDL_WINDOW_OPENGL, as follows

window = SDL_CreateWindow(p_title, SDL_WINDOWPOS_UNDEFINED, SDL_WINDOWPOS_UNDEFINED, p_w, p_h, SDL_WINDOW_OPENGL | SDL_WINDOW_RESIZABLE);

Then create opengl Context , And initialization glad

SDL_GL_CreateContext(window);
SDL_GL_SetSwapInterval(0);
SDL_SetHint(SDL_HINT_RENDER_DRIVER, "opengl");
gladLoadGLLoader((GLADloadproc)SDL_GL_GetProcAddress);

Check where you created the renderer , Does your renderer support opengl

renderer = SDL_CreateRenderer(window, -1, SDL_RENDERER_ACCELERATED);
// Check for support OPENGL, If exit is not supported , Exit code  8
SDL_RendererInfo rendererInfo;
SDL_GetRendererInfo(renderer, &rendererInfo);
if (strncmp(rendererInfo.name, "opengl", 6)) std::cout << "88888" << std::endl;;

In this way, the initialization work is done

Explain it. , The above steps are to make the renderer support opengl

My original intention is to write before SDL_Renderer Rendering UI The part of is not disturbed , At the same time, introduce opengl, Fortunately, these two can work at the same time , It saves the trouble of rewriting .

Reference link

pit 2 glad And SDL_opengl

Because I am also a beginner , It may not be right , Everyone criticizes learning

glad This third-party library can help us find opengl Function of

SDL_opengl Inside is sdl Self contained opengl Function of , You need to add opengl32 Otherwise, compile and report an error

The result of the current test is SDL_opengl The functions inside can be compared with sdl Good combination ,glad Can also be used, but with sdl The default rendering function conflicts .

I'm too lazy to write , To be continued