[MAXScript] Unable to Convert

[Nukie]

Hi,

I have started learning MAXScript, and for that I'm following the tutorials that come with max. At this point I'm following the "How To" tutorials, and so far i'm at tutorial 5 "Selecting Non-Quad Polygons".

The tutorial itself is clear and it also works, but I thought "Lets try some things for myself" so instead of making a MacroScript I'm trying to create a rollout with 2 buttons: One for selecting the Non-Quads and one for deselecting them. Now this isnt so much of a problem and the rollout works, but the button (so far I'm still trying to get the "Select All" button to work) doesnt.

When I select my model (for testing I'm using a simple GeoSphere converted to Edit Poly) the script gives me the following error:

-- Unable to convert: true to type: Integer

The error highlights this line from the code:

polyop.setfaceselection base_obj face_selection

And here is the complete code:

rollout SelectNonQuads "Select all Non-Quad Polygons"
(
	label lab "Select all Non-Quad Polygons"
	button select "Select All" pos:[10,30]
	button deselect "Deselect All" pos:[80,30]
	
	on select pressed do
	(
		local face_selection = #()
		local base_obj = $.baseobject
		local num_faces = polyop.getnumfaces base_obj
		
		for f = 1 to num_faces do
		(
			local num_face_verts = polyop.getfacedeg base_obj f
			if num_face_verts != 4 do face_selection[f] = true
		)
		
		polyop.setfaceselection base_obj face_selection
		max modify mode
		modpanel.setcurrentobject base_obj
		subobjectlevel = 4
	)
)

createdialog SelectNonQuads width:160 height:60

Maybe worth to mention I'm not a die-hard programmer

[Nukie]

230 pageviews and noone knows whats wrong?

[Mr. Bluesummers-3DT]

Quick Reply
Hmm...I think its because part of your code is trying to access an integer to select faces, but it's not getting the right type of data.

if num_face_verts != 4 do face_selection[f] = true

I bet that's the offending line. It's setting a {true,false,true,false} bit array when the polyOp method is expecting a {1,2,3,...n} list of faces to select. I'm at work so I can't fix the code for you, but that's probably where the problem is!

P.S. Try to "append" the array with face f rather than setting a bit at f. Your new line should resemble

if num_face_verts != 4 do face_selection = append face_selection f

[Mr. Bluesummers-3DT]

P.S.
MaxScript isn't discussed in this community as much as it should. I'm sorry so much time has passed since you posted!

[Nukie]

Hey thanks man. No problem it took a while, I'm glad someone could help me. The code you gave me works perfectly.

Can you please explain me what the "append" part does? As I said I'm not a die hard programmer but I want to learn it.

[Mr. Bluesummers-3DT]

Quick Reply
No worries. The help file says:

append <array> <value>
Append value to array, growing it as necessary. Returns the resulting array.

It takes the array you passed it, slams the <value> parameter onto the end, and returns the resulting array. Below are some lines about how that works:

--Let's have an array
thisArray = #("cherry", "grape", "lime")

--Let's append another flavor!
append thisArray "orange"

--Wo oh, append doesn't alter the array, it returns the result.  We didn't catch it!
format "This array contains: %\n" thisArray

--Here's how we can catch the operation's result into the same array...
thisArray = append thisArray "orange"

--Just to double check.
format "This array contains: %\n" thisArray

The important thing to note here is that it doesn't modify the array directly; it returns the appended array. You have to assign it back into a variable, or it won't count. Not all array operations work like this, so it's important to keep the documentation handy when you're coding.

Happy scripting!

[Mr. Bluesummers-3DT]

P.S.
Well, color me confused! It's not supposed to work like that, but I tested out that code block in Max8 and it appended the array without having to reassign. Wierd!

I guess you can go ahead and use

append thisArray "orange"

and count on it appending the array properly. *Shrug*

[Nukie]

Thanks for clearing it up...