In this lesson video, we are going to discuss about how to assign materials in blender. If you want to follow along right away, you can download the file I provided for this lesson. Imagine the scenario, if in a single scene, you have multiple objects made of gold, will it be a waste of time, if you have to select each of these objects, and then create the same exact gold material again and again, this is the reason why in blender and also in other 3d applications, materials and 3d models are structured as separate entities, materials are not the subordinate of 3d models and vice versa. 3d models are not the subordinate of materials, we can freely link one material to many 3d objects, and link many materials to a single 3d object. First, we will cover how to assign one material to multiple objects. And then after that, we will learn how to assign multiple materials to a single object.

Let's create a gold material for his sphere object, select the sphere, and then open the material properties panel, create a new material, and then change the metallic value to one because as we all know, gold is a metal material, then change the base color here to a yellow color. Next, let's reduce the roughness here to 0.1. Now we have a nice looking gold material. Let's rename this material to metal gold. Okay, next, let's say you want to make this sphere to be gold. Also, instead of creating the material from scratch, you can just use the same gold material that you have just created.

To do that, select the object first, then open the material properties panel. Now instead of clicking the New button here, you can click on this small button on the left side. Notice Blender will list all of the existing materials in a scene, just the metal gold material. Now as we can see, we have two objects using the same material. Notice if we tweak this material, let's say by changing the base color from yellow to blue, for example, not only this sphere object change, but also this sphere object. So this is something you need to keep in mind.

If you share material across multiple objects, changing the material will change the look of every object linked to that material. Let's change this gold material back to yellow by pressing Ctrl Z. We can put multiple materials inside one object by creating multiple material slots, and then assigning faces to those material slots in the edit mode. Let's see how we can do this on this cube object. So select the cube object and then open the material properties panel. Click the plus button up here three times to create three new material slots.

Next, just the top material slot and create a new material by clicking on the New button here. Let's change the base color to a dark gray color almost black, then change the roughness value to 0.8 and rename this material to rubber black. Next, let's click on the second slot and then create a new material, change the base color to red and then change the roughness value to 0.2. Rename the material to plastic dot read. For the less material slot. We can use the existing growth material for this.

So instead of clicking the New button, we can click in here and then choose the metal gold material from the list. Now we have three material slots. Each contains different material, but notice how the cube object looks Only the black rubber material is used by the cube object. It is like the second and the third material slots have no effect whatsoever to the object. Why is that? Well, this is because in order for you to use the material slots other than the first slot, you need to assign them first to the objects faces in the edit mode.

So move the mouse cursor to the 3d viewport and then press tab to go to the edit mode. As you can see, in the edit mode, we have additional options here that were not available before when we are in the object mode. Next, go to the face mode by pressing three on the keyboard and then select this face up here. Next, select the second slot. Now click on this Assign button here. As you can see, now the upper face of the cube uses the material in the second slot.

We can do this again for this phase for example, select the third slot and then hit the Assign button here. Okay, one thing I need to stress out here is that these face assignments are tied to the material slots and not to the material itself. So for example, this upper face is not actually tied to the red plastic material, but it is tied to the second material slot. If we click this X button here, the material is removed from the slot, but we still have the link between the faces and the material slot. If we click here and change the material to the gold material, for example, the upper face now uses the golf material just like this side face here, which is assigned to the third material slot.