Selecting MaterialIDs MaxScript

NZA · Aug 2009

Hello,

I'm quite new to Maxscript and I've been trying to write a simple function that will return true or false if any faces have a specified MaterialID applied to them. I got it working but only by collapsing the object into and editable_poly or editable_mesh. Ideally I would like to be able to add a modifer to the top of the stack and use that to perform the check and then remove it before the user is any the wiser. Heres what I have so far;

fn CheckForMaterialID obj index = 
(
    PolyList = #()
    
    max modify mode
    MatChkMod_01 = Edit_Poly()
    MatChkMod_01.name = "MaterialIDCheck"
    addModifier obj MatChkMod_01
    
    subObjectLevel = 4
    MatChkMod_01.selectByMaterialID = index
    MatChkMod_01.selectByMaterialClear = true
    MatChkMod_01.ButtonOp #SelectByMaterial 
    
-- the script gets this far - successfully selects the polys but 
-- then I'm unable to do a count of them

    PolyList = polyop.getFaceSelection obj
    print PolyList.count
     
    deleteModifier obj MatChkMod_01   
)

Is there any other way (cleaner or faster) of doing this?

Thanks :thumbup:

[PB]Snoelk · Aug 2009

maybe this helps

fn CheckForMaterialID obj index = 
(
    PolyList = #()
    InUse = False
    
    MatChkMod_01 = Edit_Poly()
    MatChkMod_01.name = "MaterialIDCheck"
    
    addModifier obj MatChkMod_01
    
    obj.EditablePoly.selectByMaterial index clearCurrentSelection:true
    
    PolyList = (obj.EditablePoly.GetSelection #Face) as array
    
    if PolyList.count > 0 do
         (
            InUse = True
         )
         
    deleteModifier obj MatChkMod_01   

    return InUse
)

obj = selection[1]
index = 1

if (CheckForMaterialID obj index) then
    (
        print ("Material ID "+index as string +" is in use on Entity "+obj.name as string)
    )
else
    (
        print ("Material ID "+index as string +" is NOT in use on Entity "+obj.name as string)
    )

NZA · Aug 2009

Thanks for the post back Snoelk I meant to update this thread to say that I solved the issue I was having. There were a couple of things wrong with my script:

When you give a number to the Edit_Poly.selectByMaterialID property it has to be one less than that of the MaterialID you really want. So if your after MatID 2 then you should give the function 3.

I was trying to perform a 'count' on a bitarray which didn't yield the result I was expecting. But by converting it to a standard array (which I can see you did in your script) the 'count' function returns the number of faces selected - which is what I wanted.

Thanks for the help and I'm going to try implementing my script using the EditablePoly functions rather than the EditPoly ones like you have in your snippet of script. :-)

MoP · Aug 2009

If you want to get a "count" of values set in a BitArray without converting to an Array, you can just use:

<bitarray>.numberSet

Since <bitarray>.count will return the number of elements in the BitArray regardless of whether they're set on or off.

NZA · Sep 2009

Cheers for the tip MOP.

I'll have to learn more about bitarrays in MaxScript and how to use them.

[PB]Snoelk · Sep 2009

bitarray are pretty cool for some nice operation. so you dont have to run over a set of faces, edges or vertices.

here a nice example to get a outline of a current faceselection
works pretty fast

function FaceSelection_Outline objtosel =
    (
        local varfacelist1 = #{}
        local varfacelist2 = #{}
        local varedgearray1 = #{}
        local varedgearray2 = #{}
        local VarTheEdge = #{}
        
        --get the current face selection as bitarray
        varfacelist1 = polyOp.getFaceSelection objtosel

         --set face selection from inverted bitarray    
        polyOp.SetFaceSelection objtosel -(varfacelist1)

        --get the inverted face selection as bitarray
        varfacelist2 = polyOp.getFaceSelection objtosel 
        
        --get the all edges from the bitarray selections
        varedgearray1 = polyOp.getEdgesUsingFace objtosel varfacelist1
        varedgearray2 = polyOp.getEdgesUsingFace objtosel varfacelist2
        
        --multiply both edge bitarray to get the outline edges between them
        VarTheEdge = varedgearray1 * varedgearray2 
        
        subobjectlevel=2
        
         -- select the edge 
        polyOp.SetEdgeSelection objtosel VarTheEdge    
        
        local varfacelist1 = #{}
        local varfacelist2 = #{}
        local varedgearray1 = #{}
        local varedgearray2 = #{}
        local VarTheEdge = #{}
        
        gc()        
    )

MoP · Sep 2009

Cool stuff, Snoelk.

Out of interest, why do you zero the local bitArrays at the end of the script? Surely since they're local they'll be discarded once that function ends?
Also any reason why you declare the bitarrays explicitly empty beforehand, instead of just doing:

local varfacelist1 = polyOp.getFaceSelection objtosel

Cheers

[PB]Snoelk · Sep 2009

i initialising those arays empty and clearing them at end just in case. maxscripts sometimes doing crazy stuff with variables. :poly122:
got a bug today with array that where not initialized at the beginning. they just memory garbage from an other variable that wasnt cleared at end.

Selecting MaterialIDs MaxScript

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