checking that an object exists

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checking that an object exists

checking that an object exists

2005-04-07 - By Bradley R. Gabe

Back

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

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
>---
>Unsubscribe? Mail Majordomo@(protected) with the following text in body:
>unsubscribe xsi

<html>
<body>
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 
<blockquote type=cite class=cite cite="">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 
</blockquote></body>
</html>