[PATCH 3/6] glamor: Add a note about the state of GL_ARB_map_buffer_range.

[Markus Wick]

Am 2014-03-06 18:00, schrieb Eric Anholt:
> +    /* We'd like to require GL_ARB_map_buffer_range or
OpenGL ES 3 or
> +     * GL_OES_map_buffer_range, since it offers more information to
> +     * the driver than plain old glMapBuffer() or glBufferSubData().
> +     * It's been supported on Mesa on the desktop since 2009 and on
> +     * GLES2 since October 2012.  It's supported on Apple's iOS
> +     * drivers for SGX535 and A7, but apparently not on most Android
> +     * devices (the OES extension spec wasn't released until June
> +     * 2012).
> +     *
> +     * 82% of 0 A.D. players (desktop GL) submitting hardware reports
> +     * have support for it, with most of the ones lacking it being on
> +     * Windows with Intel 4-series (G45) graphics or older.
> +     */
>      if (glamor_priv->gl_flavor == GLAMOR_GL_DESKTOP) {
>          if (gl_version < GLAMOR_GL_VERSION_ENCODE(1, 3)) {
>              ErrorF("Require OpenGL version 1.3 or later.\n");

glMapBuffer was dropped in OpenGL ES3, so we also have to check for this 
version to enable glMapBufferRange.
But keep in mind that most current mobile drivers doesn't support unsync 
mapping.