openvrml-develop

[openvrml-develop] shared_ptr<scope> and scope*

[Murashov G. <Mur...@se...>]

Hi.

Could you tell me, please, how function
openvrml::node_type::create_node() is supposed to be used?
I'm asking, because I'm little bit confused that one get shared_ptr<
scope > as parameter and openvrml::node use shared_ptr inside, but
node::scope() and scene::root_scope() return scope& and scope*.
Is it bug?

Another question: everywhere, working with object openvrml::node,
intrusive_ptr is used, but openvrml::scope::find_node() returns
openvrml::node*. Although in this case safe work is possible, I think
that it is not in right way.

Gleb.

Re: [openvrml-develop] shared_ptr<scope> and scope*

[Braden M. <br...@en...>]

On Wed, 2008-07-23 at 12:31 +0400, Murashov Gleb wrote:
> Hi.
> 
> Could you tell me, please, how function
> openvrml::node_type::create_node() is supposed to be used?
> I'm asking, because I'm little bit confused that one get shared_ptr<
> scope > as parameter and openvrml::node use shared_ptr inside, but
> node::scope() and scene::root_scope() return scope& and scope*.
> Is it bug?

No. Nodes participate in ownership of scopes. There's not a reason to
propagate ownership of scopes to other types of objects.

node_type::create_node is a rather low-level operation from OpenVRML's
perspective. That is not to say that you shouldn't be using it; just be
aware that browser::create_vrml_from_stream may be an appropriate
alternative.

> Another question: everywhere, working with object openvrml::node,
> intrusive_ptr is used, but openvrml::scope::find_node() returns
> openvrml::node*. Although in this case safe work is possible, I think
> that it is not in right way.

You can safely construct an intrusive_ptr from a raw pointer whenever
you need to create an owning pointer. (Notwithstanding, of course, the
potential to create ownership cycles--which you are responsible for
avoiding/accommodating.)

-- 
Braden McDaniel                           e-mail: <br...@en...>
<http://endoframe.com>                    Jabber: <br...@ja...>

Re: [openvrml-develop] shared_ptr<scope> and scope*

[Murashov G. <Mur...@se...>]

 
On Wed, 2008-07-23, Braden McDaniel wrote:
> node_type::create_node is a rather low-level operation from OpenVRML's

> perspective. That is not to say that you shouldn't be using it; just 
> be aware that browser::create_vrml_from_stream may be an appropriate
alternative.

I've used browser::create_vrml_from_stream successfully, but I can't
understand, which scope got created node.

	field_value_listener< mfnode >& fvl_add =
group_node->event_listener< mfnode >("addChildren");

	std::stringstream sss;
	sss << "DEF main_TS TouchSensor {}";
	mfnode::value_type nodes_for_mfnode =
browser.create_vrml_from_stream(sss);

	mfnode mfn(nodes_for_mfnode);
	fvl_add.process_event(mfn, 0.0);

	...

	node* f_n = root_scope.find_node("main_TS");
	// f_n == 0 :(

TouchSensor is created and works, but created node doesn't appear in
root_scope. Where can I find that? Is there any possibility to manage
this?


Getting back to node_type::create_node(). If we can't use this function
outside library, it would be better to remove this one from public
interface?


Another thing. I've found small bug in openvrml-xembed and
mozilla-plugin interaction. And I don't know how bug-tracking have to be
used, so I write here. =)

openvrml-0.17.6\mozilla-plugin\src\openvrml.cpp : 442
	command << "new-stream " << ptrdiff_t(stream) << ' ' << type <<
' ' << stream->url << '\n';
openvrml-0.17.6\mozilla-plugin\src\openvrml.cpp : 460
	command << "destroy-stream " << ptrdiff_t(stream) << '\n';

Signed type ptrdiff_t is using.

openvrml-0.17.6\src\openvrml-xembed\main.cpp : 149-151
	size_t stream_id;
	std::string type, url;
	command_line_stream >> stream_id >> type >> url;
openvrml-0.17.6\src\openvrml-xembed\main.cpp : 172-173
	size_t stream_id;
	command_line_stream >> stream_id;

Unsigned type size_t is using.

That was reason my system crash during plug-in initialization. This
happens from time to time.

Gleb.

Re: [openvrml-develop] shared_ptr<scope> and scope*

[Braden M. <br...@en...>]

Murashov Gleb wrote:
>  
> On Wed, 2008-07-23, Braden McDaniel wrote:
>> node_type::create_node is a rather low-level operation from OpenVRML's
> 
>> perspective. That is not to say that you shouldn't be using it; just 
>> be aware that browser::create_vrml_from_stream may be an appropriate
> alternative.
> 
> I've used browser::create_vrml_from_stream successfully, but I can't
> understand, which scope got created node.
> 
> 	field_value_listener< mfnode >& fvl_add =
> group_node->event_listener< mfnode >("addChildren");
> 
> 	std::stringstream sss;
> 	sss << "DEF main_TS TouchSensor {}";
> 	mfnode::value_type nodes_for_mfnode =
> browser.create_vrml_from_stream(sss);
> 
> 	mfnode mfn(nodes_for_mfnode);
> 	fvl_add.process_event(mfn, 0.0);
> 
> 	...
> 
> 	node* f_n = root_scope.find_node("main_TS");
> 	// f_n == 0 :(
> 
> TouchSensor is created and works, but created node doesn't appear in
> root_scope. Where can I find that? Is there any possibility to manage
> this?

openvrml::scope corresponds to a lexical scope for DEF/USE names. As 
such, the nodes created from create_vrml_from_stream have their own root 
scope that is distinct from the scene's. The only way to get to this 
scope is through a node (i.e., openvrml::node::scope).

Can you tell me more about what you're trying to accomplish? Perhaps 
there's another approach that would work better.

> Getting back to node_type::create_node(). If we can't use this function
> outside library, it would be better to remove this one from public
> interface?

I don't know of anything that prevents this function from being usable 
by clients of libopenvrml. It just doesn't present the simplest 
interface for creating nodes from VRML text.

> Another thing. I've found small bug in openvrml-xembed and
> mozilla-plugin interaction. And I don't know how bug-tracking have to be
> used, so I write here. =)

OpenVRML uses the SourceForge tracker. Don't worry too much about 
getting the bug categorization exactly right; that can generally be 
adjusted ad hoc.

> openvrml-0.17.6\mozilla-plugin\src\openvrml.cpp : 442
> 	command << "new-stream " << ptrdiff_t(stream) << ' ' << type <<
> ' ' << stream->url << '\n';
> openvrml-0.17.6\mozilla-plugin\src\openvrml.cpp : 460
> 	command << "destroy-stream " << ptrdiff_t(stream) << '\n';
> 
> Signed type ptrdiff_t is using.
> 
> openvrml-0.17.6\src\openvrml-xembed\main.cpp : 149-151
> 	size_t stream_id;
> 	std::string type, url;
> 	command_line_stream >> stream_id >> type >> url;
> openvrml-0.17.6\src\openvrml-xembed\main.cpp : 172-173
> 	size_t stream_id;
> 	command_line_stream >> stream_id;
> 
> Unsigned type size_t is using.
> 
> That was reason my system crash during plug-in initialization. This
> happens from time to time.

Hm... Good point. This really should use size_t consistently.

This is probably worth going ahead and fixing; however, I'm in the 
middle of ripping out this pipe-based custom IPC solution in favor of 
D-Bus interfaces.

-- 
Braden McDaniel                      e-mail: <br...@en...>
<http://endoframe.com>               Jabber: <br...@ja...>

Re: [openvrml-develop] shared_ptr<scope> and scope*

[Braden M. <br...@en...>]

Braden McDaniel wrote:
> Murashov Gleb wrote:
>>  
>> On Wed, 2008-07-23, Braden McDaniel wrote:
>>> node_type::create_node is a rather low-level operation from OpenVRML's
>>> perspective. That is not to say that you shouldn't be using it; just 
>>> be aware that browser::create_vrml_from_stream may be an appropriate
>> alternative.
>>
>> I've used browser::create_vrml_from_stream successfully, but I can't
>> understand, which scope got created node.
>>
>> 	field_value_listener< mfnode >& fvl_add =
>> group_node->event_listener< mfnode >("addChildren");
>>
>> 	std::stringstream sss;
>> 	sss << "DEF main_TS TouchSensor {}";
>> 	mfnode::value_type nodes_for_mfnode =
>> browser.create_vrml_from_stream(sss);
>>
>> 	mfnode mfn(nodes_for_mfnode);
>> 	fvl_add.process_event(mfn, 0.0);
>>
>> 	...
>>
>> 	node* f_n = root_scope.find_node("main_TS");
>> 	// f_n == 0 :(
>>
>> TouchSensor is created and works, but created node doesn't appear in
>> root_scope. Where can I find that? Is there any possibility to manage
>> this?
> 
> openvrml::scope corresponds to a lexical scope for DEF/USE names. As 
> such, the nodes created from create_vrml_from_stream have their own root 
> scope that is distinct from the scene's. The only way to get to this 
> scope is through a node (i.e., openvrml::node::scope).

I was very tired when I wrote the above response. In case it's not 
clear, you can get the root scope associated with the nodes read from 
the stream as follows:

   const openvrml::scope & s = nodes_for_mfnode[0]->scope();

You can then use openvrml::scope::find_node on s as you do with 
root_scope in the code above.

Of course, if all you want is a pointer to main_TS, 
"nodes_for_mfnode[0]" is a perfectly reasonable way to get it (in this 
case).

-- 
Braden McDaniel                      e-mail: <br...@en...>
<http://endoframe.com>               Jabber: <br...@ja...>