Materials and SubTools

From ZBrush Info

by Matthew Yetter

Contents 1 Assigning Materials to SubTools 1.1 Basic Concepts 1.2 Step by Step 1.3 Changing Materials 1.4 Painting with Materials 1.5 Returning to Default Behavior 1.6 Conclusion

Assigning Materials to SubTools

Ok, you’re creating a complex model with lots of subtools. Now you’d like each subtool to have its own material. But every time you select a new material, it is applied to every subtool rather than just the selected one. What do you do?

It’s actually very easy, and this tutorial will explain how.

For this tutorial, we’re going to use the DemoSoldier model, which is included with ZBrush 3. It’s a great one for this subject because it has 11 subtools, and most of these would do well with different materials applied.

Basic Concepts

If you’re already familiar with PolyPainting, then you already know how to assign materials to your subtools. You just might not know that you know it! With PolyPainting, you simply select a color and then fill the object with that color (using Color:Fill Object). Figure 1 shows where this button is found in the Color menu. This then colors the polygons of your subtool with that base color so that you can begin painting.

What most people don’t realize is that Color:Fill Object isn’t just for color. It can also fill the object with material. The way to tell ZBrush what you want is through the Draw menu. As Figure 2 shows, these buttons are also found on the top shelf in the standard interface layout.

• Draw:Rgb fills the object with color, only.
• Draw:M fills the object with material, only.
• Draw:Mrgb fills the object with material and color, both.

It should be noted that M has a caveat: Any subtool with a material assigned to it must also have a color assigned. So if you’re filling the model for the first time and just have Draw:M selected, ZBrush will fill the object with both material and color. The color used in this case will be white, regardless of what color is currently selected.

Step by Step

With the basic concept covered, let’s put it into action.

• Load the DemoSoldier model.
• Make sure that the body is selected. Go to Tool:SubTool and select the top subtool (called “DemoSoldierCopy1”).
• Select the MatCap Skin05 material. All of the model’s subtools will now have this material applied. That’s because no individual materials have been assigned to them yet.
• Activate Draw:Mrgb. We COULD just use M here, but as mentioned above the model will still get assigned a color with the first fill. It’s good to get in the habit of choosing Mrgb right off the bat.
• Press Color:Fill Object

That’s everything that’s necessary to assign a material to a subtool. Of course, nothing will appear to have changed yet on the canvas. But if you take a look at the SubTool menu you will see that this subtool now looks different from the others as shown in Figure 3. Let’s move on to other parts of the model.

• Select the Shirt subtool.
• Choose the FastShader 2 material. Now you’ll see all the subtools update to show the new material, except for the body (which has already had a material assigned, so now operates independently of the rest of the model).
• Let’s give him a navy blue t-shirt. Use the Color menu to select something appropriate.
• Draw:Mrgb is still selected, so go ahead and press Color:Fill Object. The preview in the SubTool menu updates to show this change.
• Repeat this process with the remaining subtools. Choose an appropriate material (such as the Basic Material) and color for each. You’ll finish with something like Figure 4.

Note: If you wish to reselect a color or material that you’ve already used for another part of the model, it’s a snap! Click on either the color or material thumbnail (depending on what info you want to get) and while the mouse button is still held down, drag out onto the canvas. The pointer becomes a Picker. When you release the mouse button, ZBrush will select the material or color that happens to be under the picker at that moment.

When you’re done with all the subtools, one thing will be painfully obvious: Our soldier needs a pair of pants!

Changing Materials

Now that you’ve assigned color and material to your subtools, you’re not stuck with those choices. You can change to a new material at any time. Let’s do something with the goggles.

• Select the goggles subtool.
• Select the MatCap GreenClay material.
• Activate Draw:M as shown in Figure 5. Since color and material have already been assigned to this subtool, we can now change either of them whenever we’d like. Setting M tells ZBrush that we’re only going to change the material, and leave the color alone.
• Press Color:Fill Object to replace the material for this subtool.

Painting with Materials

Polypainting is not just for color. You can use it to paint materials onto parts of a subtool as well. Before we can do this, it’s important to understand a difference between how polypainting handles color and how it handles material:

When you paint colors onto a model, you are really coloring individual points. ZBrush then applies that color to all polygons sharing the colored point. If your model has higher subdivision levels, ZBrush blends the point colors together across the surface of the higher level polygons. Only one color is still applied to each poly, but taken as a whole you get a gradient. This gives nice, smooth transitions as you color the model. Of course, the more points that you have, the more detailed you can get and the better the overall results will be.

Figure 6 shows this in action. First, a cube was painted at level 2. Only four points were painted as shown, with a different color for each. ZBrush applied the selected color to all polygons sharing that point, with very blocky results. Level 7 was simultaneously shaded, but here we can see how the colors have been blended together across the subpolygons.

Materials are different, though. They cannot be blended between. This means that each polygon of your surface can have one material applied to it, and all subpolygons will share the same material as their parent. So in order to get good quality polypainting with materials, you need to either have a dense mesh or be able to place the demarcation line someplace that would be natural.

We can use this second option to make the soldier a bit more modest:

• Select the DemoSoldierCopy1 subtool, which is currently all flesh-tone.
• We already have the MatCap GreenClay material selected. That one would actually be pretty good for pants, so we’ll leave it selected.
• We only want to paint with material, so be sure that Draw:M is still the selected choice.
• By default, Draw:Zadd is active. That has been fine so far because we haven’t been painting on the model. We need to turn it off now, though.
• Now just paint on the model where the pants should be, covering everything that’s visible below the belt. This is standard polypainting, except that we’re only using material instead of color. (Although with Draw:Mrgb active, we could also paint with both.)

You can now really see what I was talking about earlier, where each polygon has only one material applied to it. In the SubTool menu, click on the eye icon for the DemoSoldierCopy1 subtool to hide the other subtools. Notice how the edges are really blocky as shown in Figure 7? This is because there aren’t many polygons for the model. That really doesn’t matter in this case because those edges are normally hidden underneath the model’s other subtools. But if you actually needed better edges, you would have two choices:

Make sure to paint along a natural edge loop. This will create a straight line even with few polygons.

--or—

Subdivide the model so that it has more polygons. You can then paint diagonally without it being so visible.

Returning to Default Behavior

Sometimes you might like to return a subtool to its default behavior of using whatever material is currently selected in the Material palette. To do this, simply fill the subtool with the FlatColor material. This essentially erases the embedded material from the subtool. From that point forward, any time you select a new material the subtool will immediately update to use that material.

To return the entire model to this default behavior you will need to fill each subtool individually with the FlatColor material.

Conclusion

That’s it! Using the very simple principles outlined in this tutorial you now know how to apply different materials to each individual subtool, how to change those materials later, and even how to paint multiple materials onto a single subtool. The possibilities are virtually limitless, so enjoy!