RE: Accessing UserDataBlob from Mental Ray

["Mathieu Leclaire" <mleclair(at)hybride.com>]

Title: Re: Accessing UserDataBlob from Mental Ray

that's right... it returns a pointer. My mind was elsewhere when I responded. Thanks for correcting me. Sorry Philipp. I'll try to be more focused next time I respond.

 

Mathieu

-----Original Message-----
From: owner-xsi(at)Softimage.COM [mailto:owner-xsi(at)Softimage.COM]On Behalf Of Halfdan Ingvarsson
Sent: Wednesday, June 14, 2006 9:04 AM
To: XSI(at)Softimage.COM; XSI(at)Softimage.COM
Subject: RE: Accessing UserDataBlob from Mental Ray

Eh.

 

miQ_DATA_PARAM gives back a *pointer*. It does not copy anything. The other thing is, if you initialise a UserDataBlob with a string, the string is a UNICODE string, not ASCII. So each character is two bytes. To wit:

 

wchar_t* wcsDataString;
mi_query(miQ_DATA_PARAM, NULL, tTheData, &wcsDataString);
mi_info( "*****Data String: %ls", wcsDataString);

 

Note red bits. This should work on both Windows and Linux.

 

 - ½

---

From: owner-xsi(at)Softimage.COM on behalf of Philipp Oeser
Sent: Wed 14-Jun-06 06:11
To: XSI(at)Softimage.COM
Subject: Re: Accessing UserDataBlob from Mental Ray

Eh...where was my "C for dummies"-book again?  :-[
Thanks Mathieu, trying out right now...

Greetings
Philipp


Mathieu Leclaire schrieb:
> try:
>
> miInteger iDataSize;
> mi_query(miQ_DATA_PARAM_SIZE, NULL, tTheData, &iDataSize);
> mi_info( "*****Data Size: %d", iDataSize);
>
> char* sDataString = new char[iDataSize];
> mi_query(miQ_DATA_PARAM, NULL, tTheData, sDataString);
> mi_info( "*****Data String: %s", sDataString);
>
>
> ...and don't forget to release the memory once you don't need sDataString
> anymore calling:
>
> delete [] sDataString;
>
>
> ...I beleive that should work... try it out and let me know.
> To explain: allocate memory with new... since it's a pointer, mi_query
> without the & and release the memory at the end.
>
>
> Mathieu Leclaire
> R&D Programmer
> Hybride Technologies
>
>
> -----Original Message-----
> From: owner-xsi(at)Softimage.COM [mailto:owner-xsi(at)Softimage.COM]On Behalf
> Of Philipp Oeser
> Sent: Tuesday, June 13, 2006 8:13 AM
> To: xsi(at)Softimage.COM
> Subject: Accessing UserDataBlob from Mental Ray
>
>
> Hi,
> second try at getting particle positions over to MentalRay (first was to
> read theParticleUserData directly but still cant do it).
> So this time: with own UserData. But I am having problems with
> retrieving the UserData from within a shader in MR. All I get is the
> first character of a string...
> so if I put "example" in a blob-string, in MentalRay I only get "e".
> I hope this is just some newbie C-thing or something, so if you can help
> me out, I'd be really happy :)
>
> So, in XSI i ad d the blob to my selection (in this case just a grid)
> and save a string with:
> (this is just scripting, not C++, so as I understood I can only save
> strings with it...)
> ............................................................................
> ...................
>
> set oSel = Selection(0)
> set oBlob = oSel.AddProperty( "UserDataBlob", , "data" )
> oBlob.Value = "example"
> SetValue oBlob&".RenderData", True
> SetValue oBlob&".UserDataID", 1111111
> .............................................................................
> ...................
>
>
> And, in MentalRay :
> ............................................................................
> ...................
>
> char *sTheData = "grid/data";
> miTag tTheData = mi_api_name_lookup(sTheData);
>
> miInteger iDataSize;
> mi_query(miQ_DATA_PARAM_SIZE, NULL, tTheData, &iDataSize);
> mi_info( "*****Data Size: %d", iDataSize);
>
> char* sDataString;
> mi_query(miQ_DATA_PARAM, NULL, tTheData, &sDataString);
> mi_info( "*****Data String: %s", sDataString);
> ............................................................................
> ...................
>
> The Data Size comes over nicely but the String ist truncated to the
> first character. So, as I said I'm pretty unstable in C and dont have a
> good understanding of what a blob is, so if you can point me in the
> right direction or tell me where i make mistakes, you'll save my day :)
>
> Greetz
> Philipp
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