Maya mel script - move selected vertices to 0 on x axis

Hupie

Hello everyone,

I'm trying to learn MEL scripting coming from a background of Unity C#.  Currently I'm working on a script that moves all selected vertices  to 0 on the x-axis. I borrowed this script from another forum but it doesn't seem to work when the object has moved:

	string $verts[] = `ls -sl -fl`;<br>	for($vert in $verts)<br>	{<br>	select $vert;<br>	float $vPos[] = `xform -q -t`;<br>	move 0 $vPos[1] $vPos[2];<br>	select -cl;<br>	}<br>

Now, I'm trying to freeze the transformations and reset the pivot point to the origin so the above script does work. However,, in order to freeze the transformations I need to go back to object mode. But it seems that  switching to object mode sometimes doesn't work. For example, when I create a new cube object, go into vertex selection mode, and select some vertices, I cannot go back to object mode with this line of code:

 selectMode -object;

Why can't I switch to Object selection mode?


This is the full script I'm working on:

global proc MoveVerticesZeroX(){<br>    <br>    selectMode -object;<br> <br>    xform  -ws -pivots 0 0 0 ;<br>    FreezeTransformations;<br>    <br>    selectMode -co;<br>    selectType -alc 0 -v 1;<br>    <br>	string $verts[] = `ls -sl -fl`;<br>	for($vert in $verts)<br>	{<br>	select $vert;<br>	float $vPos[] = `xform -q -t`;<br>	move 0 $vPos[1] $vPos[2];<br>	select -cl;<br>	}<br>}<br>

Axi5

I know you're trying to learn Mel script but if someone is looking to do this quickly and without a script, you could just use the input bar at the top in the status line.

It's in a little fly-open menu between your render settings and your account login.

Select the icon and click Absolute Transform then type 0 in the first box and hit enter.

It works on objects that have been moved but it seems to use an internal procedure called numericalInputChangeCommand abs; so it doesn't appear very useful for scripting.

Hupie

Thanks for your reply. I am deliberately trying to do this by script as I want to use this in a virtual reality plug-in I'm currently using ( https://www.marui-plugin.com/ ) . I am trying to create my own scripts that I can easily access and use from within VR .

Axi5

Rather than doing all of the freeze transformation stuff have you tried using the World Space flag on the move command?

http://help.autodesk.com/cloudhelp/2017/CHS/Maya-Tech-Docs/Commands/move.html

In one line:
move -ws -x 0

Quick demo
https://www.dropbox.com/s/7xnp6er47na8l3p/2017-12-01_19-37-29.mp4?dl=0

Hupie

That works perfectly, thank you very much!

Now I'm still wondering why the changing mode selection doesn't work...

Klaudio2U

What Axi5 said that one little line will do. 

If, however, you still want to know how to select move pivot to the origin and freeze transformation you really don't have to switch selection mode back and forward from Object to Component. The trick is that all you need is somehow to get the name of the object while you still have some components selected and without deselecting them (for example, some vertices selected). 

The script goes like this:

// get object name when any componet is selected 
string $getObjectName[] = `ls -hilite`;  

// move pivot to Origin for "$getObjectName[0]" object

xform  -ws -pivots 0 0 0 $getObjectName[0];  

// freeze transformation for "$getObjectName[0]" object

makeIdentity -apply true -t 1 -r 1 -s 1 -n 0 -pn 1 $getObjectName[0];


This will have your components still selected while "in the background" doing positioning of pivot to the origin and freeze object transformations. This kind of thing is also very useful in lots of situation when you need to do something to your object and components and will reduce the code lines instead converting selection mode back and forward.


As for going from component to object mode, you can also use the same workflow as a workaround:

// get object name when any component is selected
string $getObjectName[] = `ls -hilite`; 
 // select the object
select -r $getObjectName[0]; 


Hope this helps. 
Cheers.

Hupie

Thank you very much for your detailed answer, Klaidio2U!That is very educating for me.

Your workaround for toggling between the selection modes also seems to work well. Maybe it's me, but I'm still wondering why the

&nbsp;selectMode -object<span>;</span>

doesn't seem to work properly. Is this just a limitation/bug of the Mel scripting language or is something else going on?

throttlekitty

Hupie said:

Thank you very much for your detailed answer, Klaidio2U!That is very educating for me.

Your workaround for toggling between the selection modes also seems to work well. Maybe it's me, but I'm still wondering why the

 selectMode -object;

doesn't seem to work properly. Is this just a limitation/bug of the Mel scripting language or is something else going on?

This will only change if you used selectMode -component first, hotkeys or marking menus use a different method to enter component mode. (I forget what, offhand toggleSelSomething?)

TTools

Something to be aware of:
If you use the -hilite flag with the ls command, you can potentially get more objects returned than just the object on which you have vertices selected.
For example, make two cylinders, select both objects, press F9, then select vertices on just one of the cylinders.
If you perform:
string $getObjectName[] = `ls -hilite`;
You get:
// Result: |pCylinder2 |pCylinder1 // 

My suspicion is that you only want the transform returned upon which you have verts selected, not all "objects that are currently hilited for component selection." (Per the MEL command reference).

Also, whenever you perform an `ls` operation, it is strongly advisable to utilized the -long flag.  This will return object long names. This protects you against identical object names that could be living in different groups. 

For example:

If you have one of those cylinders selected and perform an `ls -sl`, you get a return of pCylinder1.
Now perform: select "pCylinder1"
You'll get:
// Error: line 1: More than one object matches name: pCylinder1 // 

This can really screw you over when you start writing scripts for extremely large and potentially unkempt scenes.  Better to be bulletproof from the start IMO.


Here is some code that will protect you from both issues:

string $shapeNodes[] = `ls -sl -objectsOnly -long`;  //ObjectsOnly flag gives you the shape nodes from the selected components.
// Result: |group1|pCylinder1|pCylinderShape1 // 
string $transformNode[] = `listTransforms $shapeNodes[0]`; //Gives you the transform node linked to the shape node.
// Result: group1|pCylinder1 // 

Hope this is valuable to you, and my apologies if I stepped on anyone's toes in the process 

Klaudio2U

I don't get any errors when i do as your example of objects having the same name in the separate groups. 
The only change that could be done is to use "$getObjectName" instead of "$getObjectName[0]" so that not only the first object is affected but all in the array or which objects are highlighted...which may or may not be what you want too.

But yes, no worries. There are multiple ways of doing things with scripting so i never see things are right or wrong but it's more about what someone what to do exactly. 

Hupie

Wow, Things a lot for all the detailed answers everyone! This is all very valuable information for me and can potentially save me hours of work in the future