Python Basic problems

[marcofgodai]

First problem, (I'm a noob in Python Maya)
I just want to assign a red blinn to any selected object and have the material named "changed_flag_#"
It's a functioned tied to a GUI button.

Right now, when pressed, it created a red blinn, but doesn't assign it to the object, and then when i hit it again, it creates
another blinn with the correct name, but its not red. It also gives an error. Clearly saying that the object was not selected. But I select the object before I hit the button.

CODE

def flagChanged():

RedBlinn = cmds.shadingNode('blinn', asShader=True, name='Changed_flag*')

#assign new, selected node to selected Geo

cmds.hyperShade(assign=RedBlinn)

cmds.setAttr('Changed_flag*.color', 0.9, 0.08, 0.08, type='double3')

cmds.setAttr('Changed_flag*.reflectivity', 0)

cmds.setAttr('Changed_flag*.specularRollOff', 0.2)

cmds.setAttr('Changed_flag*.eccentricity', 0.12)

ERROR

#Error:No renderable object is selected for assignment

ANY HELP?

M

[heather-howard]

import maya.cmds as cmds
 
def flagChanged():
    #Create a list of selected objects
    selected = cmds.ls(sl=1)
 
 
    name= 'Changed_flag'
    #creates the empty shading group with the proper name
    cmds.sets(renderable=True, noSurfaceShader=True, empty=True, name = name + 'SG')
    #creates a Blinn nammed changed_flag
    cmds.shadingNode('blinn', asShader=True, name=name)
    cmds.setAttr(name+'.color', 0.9, 0.08, 0.08, type='double3')
    cmds.setAttr(name+'.reflectivity', 0)
    cmds.setAttr(name+'.specularRollOff', 0.2)
    cmds.setAttr(name+'.eccentricity', 0.12)
    #Assigns the shader to the shading group
    cmds.connectAttr(name + '.outColor', name + 'SG.surfaceShader')
 
    #For each element in that list, assign it to the Shading Group set
    for i in selected:
        cmds.sets( i, e=True, forceElement= name + 'SG' )
 
#run the function
flagChanged()

The problems you had were I think just a misunderstanding about how maya assigns shaders.  You were close!

• The * character is an invalid character in a name so I took it out.
• The reason why it was giving you that error was because when it runs the line Redblinn=[...] its deselected the object. Thats because you told it to do something else (you told it do RedBlinn and redblin runs "cmds.shadingNode('blinn', asShader=True, name='Changed_flag*')" when before you told it to do that it was "doing" select.theObject).  Unless you tell it "go back and select my thingy when you finished running RedBlinn, then it's going to be selecting nothing and therefore assigning your shader to nothing, so you need to save your selection somehow.   selected = cmds.ls(sl=1) will save all your selected objects into a list called "selected" then you can use for all i in selected (or "for all items i in list 'selected'" to do things to each item i.
• Maya doesn't assign an item directly. It doesn't assign myShader directly to Object1.  It assigns the shader to a shader group and all objects in that shader group have myShader applied.  So it's not Object1->myShader. It's myShader->myShaderShadingGroup -> all Objects in the shading group. So you need to make a shading group first, then your shader, assign it to the shading group then assign your objects to the shading group.

Hope this helps!!

[marcofgodai]

THIS WAS FANTASTIC HEATHER, THANK YOU SO MUCH!!!!!

I noticed that it will work with either single selected objects OR multiple selected objects, but doesn't work in the scene more than once. How about adding the shader to any additional objects like...

if shader/shading grp already exists, apply shader to selected object?

-Marc

[heather-howard]

I'm glad you found it helpful! Have you tried to edit the above code so that it will apply an existing shader to a selected object?  I generally like to help people fix their code if I can, but only after they've tried to write the code themselves; I don't write code for people if they haven't already tried to do it themselves (I'd never be able to leave the forums if I did that).  I know how hard it is to fix code when it just isn't working. If you're having problems, please post the edited code or describe the problem you are having and I'd be happy to try and help debug it.

[joojaa]

Editted the post to include syntax highlighting.

[heather-howard]

Thank you Joojaa!