Re: [Qemu-devel] [PATCH 6/9] sdl2/opengl: add opengl context and scanout support

[Gerd Hoffmann <kraxel@redhat.com>]

  Hi,

> > +    scon->scanout_mode = scanout;
> > +    if (!scon->scanout_mode) {
> > +        if (scon->fbo_id) {
> > +            glFramebufferTexture2DEXT(GL_FRAMEBUFFER_EXT,
> > +                                      GL_COLOR_ATTACHMENT0_EXT,
> > +                                      GL_TEXTURE_2D, 0, 0);
> > +            glDeleteFramebuffers(1, &scon->fbo_id);
> 
> I'm not sure, but maybe the framebuffer itself should be unbound here,
> too? (i.e., glBindFramebuffer(GL_FRAMEBUFFER, 0))
> 
> I know it's deleted but I don't know whether that's enough.

Fixed.

> > +    glBindFramebuffer(GL_READ_FRAMEBUFFER, scon->fbo_id);
> > +    glBindFramebuffer(GL_DRAW_FRAMEBUFFER, 0);
> > +
> > +    SDL_GetWindowSize(scon->real_window, &ww, &wh);
> > +    glViewport(0, 0, ww, wh);
> > +    y1 = scon->y0_top ? 0 : scon->h;
> > +    y2 = scon->y0_top ? scon->h : 0;
> > +    glBlitFramebuffer(0, y1, scon->w, y2,
> > +                      0, 0, ww, wh,
> > +                      GL_COLOR_BUFFER_BIT, GL_NEAREST);
> 
> Should we bind the FBO back to GL_DRAW_FRAMEBUFFER after the blit operation?

Isn't READ/DRAW used for framebuffer blits only?  Normal rendering goes
to GL_FRAMEBUFFER I think ...

cheers,
  Gerd