single buffered eglSurface

[damian0815]

I have an OpenGL ES 2 app that's working fine with the default window surface:

Code: Select all

eglSurface = eglCreateWindowSurface( eglDisplay, config, nativeWindow, NULL );

When I try and make it single buffered, like this:

Code: Select all

    static const EGLint surf_attribute_list[] = {
    EGL_RENDER_BUFFER, EGL_SINGLE_BUFFER,
    EGL_NONE // attribute list is termintated with EGL_NONE
};
eglSurface = eglCreateWindowSurface( eglDisplay, config, nativeWindow, surf_attribute_list );

the returned eglSurface seems to be valid (it doesn't generate an error), but I no longer see anything drawn on the screen.

Is there something else I need to do to switch from double to single buffering?

[dom]

Our 3D guy says:

"eglSwapBuffers() doesn't do anything for single-buffered surfaces (from the EGL spec, "If surface is a single-buffered window, pixmap, or pbuffer surface, eglSwapBuffers has no effect.")

If he replaces the eglSwapBuffers() calls with eg glFlush() he should see stuff.

(Or at least that's my best guess without seeing the rest of his code)"

[damian0815]

hey Dom,

thanks for the advice, but unfortunately that wasn't enough.

I remember reading somewhere that EGL + GLES just doesn't allow single buffered surfaces when using eglCreateWindowSurface (ie, i suppose, due to the hardware design the backbuffer is always cleared every blit). I guess I can use eglCreatePixmapSurface or eglCreatePbufferSurface then treat the returned surfaces as a texture and draw them to a surface made with eglCreateWindowSurface.

The only reason all this is necessary is so that I can get a single-buffered MSAA window.