Print Material Color of Active Object

Question

I feel like I'm close on this one. I am trying to print the material color of the active object.

Currently it is printing a value, but when I select a new active object, it prints the same value. I'm sure its a really simple thing that I'm missing but I also can't seem to find the correct method.

import bpy
obj = bpy.context.view_layer.objects.active
material = obj.active_material
color = material.diffuse_color
print(color[0], color[1], color[2], color[3])

What I am attempting to do is for each active object, report back the HSV value of the material attached to it. Ultimately I am trying to batch export each file with the file name containing the hex color of the object.

Getting the HSV values is just the first step.

Answer 1

The method for obtaining the diffuse color varies depending on what render engine you are using. For EEVEE and Cycles, diffuse_color isn't used and you need to find the color input of the shader node. For example, if you have the very simple setup of a Principled BSDF feeding the Material Output Surface Input, you need to find the Base Color input of the Principled Node. Here's a very simple material:

and here's a simple example replacing your last two lines but changing your last two

obj = bpy.context.view_layer.objects.active
material = obj.active_material
inputs = material.node_tree.nodes["Principled BSDF"].inputs
color = inputs["Base Color"].default_value
print(color[0], color[1], color[2], color[3])

Note that this only works in the simple case where

• There is only one shader node
• Its node name is Principled BSDF
• It has no node connected to its Base Color input.

But the idea of a single diffuse color doesn't really apply except when you're using the workbench render engine, because even the Principled BSDF in this simple example will modify the color depending on the shape of the object its applied to, b applying the Fresnel Effect If any of this changes, you need to change the code to match. Since you mentioned you were using a diffuse BSDF in your comments, here's the code for that

obj = bpy.context.view_layer.objects.active
material = obj.active_material
inputs = material.node_tree.nodes["Diffuse BSDF"].inputs
color = inputs["Color"].default_value
print(color[0], color[1], color[2], color[3])

Answer 2

That's a common misunderstanding of the material system. Material.diffuse_color property is used for solid viewport shading (or renders created with the workbench engine) and does not affect the (final) rendering of all other engines, the main reason why you can find that property in the Viewport Display panel:

Due to the nature of node based materials (and almost endless possibilities of wiring things up), it's not that easy to get the diffuse/albedo color of a material as you might think.

If you're using e.g. just one Principled BSDF, you would have to get the material of the object, find the principled node in the node tree and read its 'Base Color' input property:

import bpy

# Get the object reference
obj = bpy.context.object

# Get the material via active slot 
mat = obj.active_material 
# or: bpy.data.materials.get("MaterialName")

if hasattr(mat, 'node_tree'):
    # Get the principled bsdf
    prince = mat.node_tree.nodes.get('Principled BSDF') 
    if prince:
        # Get the base color of the principled bsdf
        r, g, b, a = prince.inputs['Base Color'].default_value
        print(r, g, b, a)

Result

0.01615985296666622 0.04138465225696564 0.8000000715255737 1.0

Further reading

• Control Cycles/Eevee material nodes and material properties using python?
• Principled BSDF via Python API

---

HSV, sRGB and Hex triplet

In case you'd like to get the HSV color and the Hex triplet as well, you'd have to implement the actual conversion using python since there is no API function to get them:

import bpy
import colorsys
import math

def lin_to_srgb(c):
    if c < 0.0031308:
        srgb = 0.0 if c < 0.0 else c * 12.92
    else:
        srgb = 1.055 * math.pow(c, 1.0 / 2.4) - 0.055
    return max(min(int(srgb * 255 + 0.5), 255), 0)

def hextriplet(c):
    return '#' + ''.join(f'{i:02X}' for i in c)


# Get the object reference
obj = bpy.context.object

# Get the material via active slot 
mat = obj.active_material 
# or: bpy.data.materials.get("MaterialName")

if hasattr(mat, 'node_tree'):
    # Get the principled bsdf
    prince = mat.node_tree.nodes.get('Principled BSDF') 
    if prince:
        # Get the base color of the principled bsdf
        r, g, b, a = prince.inputs['Base Color'].default_value
        # Convert rgb to hsv
        h, s, v = colorsys.rgb_to_hsv(r, g, b)
        # Convert to sRGB
        srgb = [lin_to_srgb(c) for c in (r, g, b)]

        # Print the values
        print("RGBA:", r, g, b, a)
        print("HSV:", h, s, v)
        print("sRGB:", ", ".join(map(str, srgb)))
        print("Hex:", hextriplet(srgb))

Result

RGBA: 0.04373500123620033 0.09530799835920334 0.7991030216217041 1.0
HSV: 0.655287445825263 0.9452698837911484 0.7991030216217041
sRGB: 59, 87, 231
Hex: #3B57E7