checking that an object exists

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checking that an object exists

checking that an object exists

2005-04-07 - By Jason Brynford-Jones

Back

Reply: 1 2 3 4 5 6 7 8 9 10 >>

And here is a link to more

http://www.xsibase.com/forum/index.php?board=14;action=display;threadid=
17688

-- --Original Message-- --
From: owner-xsi@(protected) [mailto:owner-xsi@(protected)] On Behalf
Of Bradley R. Gabe
Sent: Thursday, April 07, 2005 3:14 PM
To: XSI@(protected)
Subject: Re: checking that an object exists

You can always try to populate an XSI collection using the items
property set to a string. If the objects don't exist in the scene, the
collection count will remain 0. Otherwise, it will fill up with the
items that match the string input. This is very fast and never raises
errors:

// Create an empty XSI collection
var findColl = new ActiveXObject('XSI.Collection');

// Find the object from the name
findColl.Items = 'objectName';

// Test the collection count
if(findColl.count>0){
var obj = findColl(0);
LogMessage(obj);
}
// -- ---- ---- ---- ---- ---- ---- ---- ------

NOTE: This is the same way the Selection object gets populated when you
type a string in the text selection box, so you can always test your
strings before you put them into your code. Also, wildcard selections
will work with this method, so you could use it to quickly grab all the
nodes in a specific model space:

// Create an empty XSI collection
var modelColl = new ActiveXObject('XSI.Collection');

// Get the name of the current selected model
var modelName = selection(0).name;

// Get all the nodes in the model space
modelColl.Items = modelName + '.*';
// -- ---- ---- ---- ---- ---- ---- ---- ------

You can also use this technique to fill a collection with multiple
parameters or properties. I like to use an Array because it reads
clearly, requires less string concatenation, and is easy to add or
remove items from:

// Create an empty XSI collection
var visColl = new ActiveXObject('XSI.Collection');

// Get the visibility parameters of the currently selected obj
var obj = selection(0);

visColl.Items = [
obj + '.visibility.viewvis',
obj + '.visibility.rendvis',
obj + '.visibility.selectability'
];

// Get pointers to the visibility params
var viewvis = visColl(0);
var rendvis = visColl(1);
var selectability = visColl(2);
// -- ---- ---- ---- ---- ---- ---- ---- ------

If you're interested in more techniques for getting object pointers and
speed comparisons, check out this link:
http://www.cg-soup.com/archives/2005/02/loopin_lizards.html

-Brad
CG Soup

Hi,

I got an interesting question from someone, that I wanted to check out
with you all.

Given an object's full name, he wants to check if it exists.

So there are two ways to do it.

Via command: GetValue()

Via object model: Dictionary.GetObject()

now here's the question:

Both of these solutions throw an exception if the given object does not
exist. While you can catch the exception, I'd think this is a poor way
to go about solving the problem. Exceptions should not be used for flow
control. They're inherently slow (or so I've been taught time and time
again). Is there a better fast way to check if an object exists from
its full name that doesn't involve depending on exceptions? I can come
up with some ways of doing it that will be inherently slow... but none
that are fast.

-brad
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And here is a link to more<o:p></o:p>

<o:p> </o:p>

<a
href="http://www.xsibase.com/forum/index.php?board=14;action=display;threadid
=17688">http://www.xsibase.com/forum/index.php?board=14;action=display;threadid
=17688</a><o:p></o:p>

<o:p> </o:p>

<o:p> </o:p>

-- --Original Message-- -- 
From: owner-xsi@(protected)
[mailto:owner-xsi@(protected)] On Behalf Of
Bradley R. Gabe 
Sent: Thursday, April 07, 2005
3:14 PM 
To: XSI@(protected) 
Subject: Re: checking that an
object exists

<o:p> </o:p>

You can always try to populate an XSI collection using
the items property set to a string. If the objects don't exist in the scene,
the collection count will remain 0. Otherwise, it will fill up with the items
that match the string input. This is very fast and never raises errors: 
 
// Create an empty XSI collection 
var
findColl = new ActiveXObject('XSI.Collection'); 
 
// Find the object from the name 
findColl.Items = 'objectName'; 
 
// Test the collection count 
if(findColl.count>0){ 
    var obj = findColl(0); 
    LogMessage(obj); 
} 
//
-- ---- ---- ---- ---- ---- ---- ---- ------ 
 
NOTE: This is the same way the Selection object
gets populated when you type a string in the text selection box, so you can
always test your strings before you put them into your code. Also, wildcard
selections will work with this method, so you could use it to quickly grab all
the nodes in a specific model space: 
 
// Create an empty XSI collection 
var
modelColl = new ActiveXObject('XSI.Collection'); 
 
// Get the name of the current
selected
model 
var modelName = selection(0).name; 
 
// Get all the nodes in the model
space 
modelColl.Items = modelName + '.*'; 
//
-- ---- ---- ---- ---- ---- ---- ---- ------ 
 
You can also use this technique to fill a
collection with multiple parameters or properties. I like to use an Array
because it reads clearly, requires less string concatenation, and is easy to
add or remove items from: 
 
// Create an empty XSI collection 
var
visColl = new ActiveXObject('XSI.Collection'); 
 
// Get the visibility parameters of
the currently selected obj 
var obj = selection(0); 
 
visColl.Items
= [ 
             
  
obj + '.visibility.viewvis', 
             
  
obj + '.visibility.rendvis', 
             
  
obj + '.visibility.selectability' 
             
  
]; 
 
// Get pointers to the visibility params 
var
viewvis = visColl(0); 
var rendvis = visColl(1); 
var selectability = visColl(2); 
//
-- ---- ---- ---- ---- ---- ---- ---- ------ 
 
If you're interested in more techniques for getting
object pointers and speed comparisons, check out this link: 
<a href="http://www.cg-soup.com/archives/2005/02/loopin_lizards.html"
eudora=autourl>http://www.cg-soup.com/archives/2005/02/loopin_lizards.html 
 
 
</a>-Brad 
CG Soup 
 
<![if !supportLineBreakNewLine]> 
<![endif]><o:p></o:p>

Hi, 
 
I got an interesting question from someone, that I wanted to check out with you
all. 
 
Given an object's full name, he wants to check if it exists. 
 
So there are two ways to do it. 
 
Via command: GetValue() 
 
Via object model: Dictionary.GetObject() 
 
now here's the question: 
 
Both of these solutions throw an exception if the given object does not
exist.  While you can catch the exception, I'd think this is a poor way to
go about solving the problem.  Exceptions should not be used for flow
control.  They're inherently slow (or so I've been taught time and time
again).  Is there a better fast way to check if an object exists from its
full name that doesn't involve depending on exceptions?  I can come up
with some ways of doing it that will be inherently slow...  but none that
are fast. 
 
-brad 
--- 
Unsubscribe? Mail Majordomo@(protected) with the following text in body: 
unsubscribe xsi<o:p></o:p>

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