[MonoTouch] OpenTK GL.Oes.Mapbuffer Access flags missing

[Jeff Stedfast]

Hi Don,
I've taken a look at the OpenTK bindings included in MonoTouch and, as
you've noted, could not find ReadOnly nor ReadWrite flags. This
prompted to me look at more recent OpenTK bindings to see if maybe
they had it (they didn't). So I started looking through the OpenGLES
headers in /Developer/Platforms/iPhoneOS.platform/Developer/SDKs/iPhoneOS4.3.sdk/System/Library/Frameworks/OpenGLES.framework/Headers/ES1/glext.h

These seem to be the flags available for use with MapBuffer:
#if GL_OES_mapbuffer
#define GL_WRITE_ONLY_OES                                       0x88B9
#define GL_BUFFER_ACCESS_OES                                    0x88BB
#define GL_BUFFER_MAPPED_OES                                    0x88BC
#define GL_BUFFER_MAP_POINTER_OES                               0x88BD
#endif

These seem to map to the following enum values in All:

        WriteOnlyOes = ((int)0x88B9),
        BufferAccessOes = ((int)0x88BB),
        BufferMappedOes = ((int)0x88BC),
        BufferMapPointerOes = ((int)0x88BD),

Unfortunately, I'm not very familiar with OpenGLES programming, so I
did a google search and found this which might be useful:

http://www.khronos.org/registry/gles/extensions/OES/OES_mapbuffer.txt

This suggests that the only actual 'access' flag is GL_WRITE_ONLY
which suggests to me that in order to get read-only, you'd use a value
of 0 and read-write would just be GL_WRITE_ONLY
(GL_WRITE_ONLY|GL_READ_ONLY == GL_WRITE_ONLY).

So, if you want read-only access, you'd do: MapBuffer (All.<target>, (All) 0);

If, instead, you want read-write access, you'd do: MapBuffer
(All.<target>, All.WriteOnlyOes);

Hope that helps,

Jeff

On Fri, Oct 7, 2011 at 12:11 PM, Don Freiling
<don.freiling at librestream.com> wrote:
>
> The OpenTK.Graphics.ES11 namespace contains the method:
>
> public static IntPtr MapBuffer (All target, All access)
>
>
>
> The only valid flags for access are ReadOnly, WriteOnly and ReadWrite.
>
>
>
> The All enumeration is missing the ReadOnly and ReadWrite flags. How do I set up a buffer with read access?
>
>
>
>
>
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