[Interest] Multisample EGL PBuffer

[Thomas Sevaldrud]

I'm setting up a EGL PBuffer for shared rendering between Qt Quick and
Direct3D, and I'm getting closer to a usable result. However, I am having
trouble getting a multisample frame config for my PBuffer.

I've tried both getting the EGL Config through the platform native
interface and using eglChooseConfig. I have multisampling enabled in my
QSurfaceFormat and in my EGL attributes, but I don't get any multisampling.

This:

    QPlatformNativeInterface *nativeInterface =
QGuiApplication::platformNativeInterface();

    EGLConfig egl_config =
static_cast<EGLConfig>(nativeInterface->nativeResourceForContext("eglConfig",
gl_context_));


Or this:


    const EGLint attribList[] =

    {

        EGL_RED_SIZE, 8,

        EGL_GREEN_SIZE, 8,

        EGL_BLUE_SIZE, 8,

        EGL_ALPHA_SIZE, 8,

        EGL_DEPTH_SIZE, 16,

        EGL_SAMPLE_BUFFERS, 1,

        EGL_SAMPLES, 4,

        EGL_NONE

    };

    EGLint iConfigs;

    EGLConfig egl_config;

    eglChooseConfig(egl_display_, attribList,

                    &egl_config, 1, &iConfigs);

The last version returns 0 configs.

Should it be possible to generate a multisample PBuffer this way? Are there
any alternative solutions, such as for instance rendering to an FBO and
then blitting to the PBuffer somehow?

- Thomas
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