finding out if an object has a material

Coding Python Support
1

for a script i make i need to know if the active object has a material, and if it hasn’t, add a new one. bpy.data would be logical, but i haven’t found a wat to know of wich opject wich material is.

2

if the object has a material:


>>> bpy.context.active_object.data.materials.items()

# if no materials associated with it
[]

# if it does have a material then it will display something like
[('Material', bpy.data.materials["Material"])]

so you can check if [] is returned, if it is… then there are no materials.

3

this returns a string and if the string isn’t empty the object has a material right?

4

experiment, it returns an empty list if no materials are associated

so you have an object with no materials, in console do this


>>> bpy.context.active_object.data.materials.items().__class__

the output will be <class ‘list’> , the class addition tells you the return type of items()

5

Or you could try:

obj = bpy.context.scene.objects.active
if len(obj.data.materials) == 0:
    newMat = bpy.data.materials.new('newmaterial')
    obj.data.materials.append(newMat)
6

thanks :slight_smile:

another question:

i am making a new image, (‘normalmap.’, random), but now i have to assign it to the active object

bpy.context.scene.objects.active.data.images.append(normalmap.007) (using the way to do it with materials) does not work, and also the bpy.ops.uv seems not to have a solution.

how frustrating that all i need is 1 line of tokens put in the right order…

7

Hi flokkievids,


# Loads image from disk (1st line) or uses an image loaded (or generated) previously (2nd line).
myImg = bpy.data.images.load('C:/path/to/the/image.jpg')
myImg = bpy.data.images['image name.jpg'] 

# Sets the texture type to image
bpy.context.active_object.material_slots['Material'].material.texture_slots['Tex'].texture.type = 'IMAGE'
# Assigns the image to the texture
bpy.context.active_object.material_slots['Material'].material.texture_slots['Tex'].texture.image = myImg

That should do the trick :slight_smile:

8

alright, that should work, but i’m getting an error 'cause i got no type extension behind a newly made image. wich extension do they have on default? i tried png so far, and also that gave an error.

9

when putting
bpy.context.active_object.material_slots[‘Material’].material.texture_slots[‘Texture.001’].texture.type = ‘IMAGE’
in the console it’s alright, but in the script it says
‘MateriaSlot has no atribute texture_slots’, why does it work in the console, and not in my script…

10

Hi flokkievids,

I copied the exact code I posted, tested it on the default Blender scene and it worked perfectly when invoked from a script. The only change was I used the first line for myImg = … and I used a path to a real image in my hard disk drive.

I think the easiest way to get correct code is to leverage the autocompletion feature (Ctrl+Space) in the console.

11

class your class
#def…
try:
has_mat = bool(active_object.material_slots[0].material)
except:
has_mat = False
if has_mat:
#your code
return {‘FINISHED’}
else
print(“error”)
return {‘FINISHED’}

i think this is the best way to find an object has a material or not :grinning: