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c++copenglsdlemscripten

How to draw SDL 2D rectangles over a 3D OpenGL scene?

I'm trying to overlay small interactive info rectangles drawn with SDL 2D over a 3D scene drawn with OpenGL. Each of itself works, but not together. The 3D model is then hidden.

SDL_Init(SDL_INIT_EVERYTHING);
SDL_GL_SetAttribute(SDL_GL_CONTEXT_PROFILE_MASK, SDL_GL_CONTEXT_PROFILE_ES);
SDL_GL_SetAttribute(SDL_GL_CONTEXT_MAJOR_VERSION, 3);
SDL_GL_SetAttribute(SDL_GL_CONTEXT_MINOR_VERSION, 0);

SDL_CreateWindowAndRenderer(m_width, m_height, SDL_WINDOW_OPENGL|SDL_WINDOW_RESIZABLE, &m_window, &m_renderer);
SDL_GLContext context = SDL_GL_CreateContext(m_window);
SDL_RenderClear(m_renderer);
SDL_RenderPresent(m_renderer);

// load vertex, fragmend shader...

glClearColor(1.0, 1.0, 1.0, 0.0);
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
glDrawElements(GL_TRIANGLES, m_indicesSize, GL_UNSIGNED_INT, BUFFER_OFFSET(0));

SDL_Rect rect;
rect.w = 50;
rect.h = 50;
rect.x = 100;
rect.y = 100;

SDL_SetRenderDrawColor(m_renderer, 255, 0, 0, 255);
SDL_RenderFillRect(m_renderer, &rect);
SDL_RenderPresent(m_renderer);

How can I solve this problem? Thxs..

Solution

  • You don't, at least for now.

    Here's the (open) bug about adding backend API state getters/setters to SDL_Renderer..

    Alternatively, create a SDL_Renderer instance that uses the software renderer & upload the bitmaps coming out of that into a OpenGL texture & composite that into your scene.