Working With Your Canvas

From ZBrush Info

Painting in ZBrush is for more than just making pretty pictures. ZBrush's paint tools are remarkably powerful, offering many features than cannot be found in any other program.

The following is not intended to teach you all the details of how to paint in ZBrush, but rather the many concepts and features that can be used to help you in your painting. Read it as an overview of what ZBrush painting offers, and then refer back to it if you later feel yourself being overwhelmed by all of the various features that are used, as we show you painting in action.

Paint Brushes

ZBrush offers many paint brushes found in other programs, plus some unique ones not found in other programs. Paint brushes are accessed via the tools popup, which can be found to the left of the canvas, or in the Tool Palette.

We won't discuss details of brushes here, but some of them will be explained in greater detail in other sections, and the Tool Palette gives brief descriptions of most of them. And of course, the way to really get to know a brush is to experiment with it.

Color Painting

Paint brushes can use color. (But color can be turned off, too.) Some brushes use two different colors, a foreground color and a background color. You'll see this in examples, and as you experiment on your own. You can look at the Color Palette reference for details of how to select colors. Do we need to say more?

Depth-Enabled Painting

This is one of the unique features of ZBrush, and an important one it is. When you paint on the canvas, you can affect not only the color but (optionally) the distance of pixels on the canvas from you, the viewer. In fact, in ZBrush, we call the smallest dots on the canvas pixols (not pixels), to indicate that in addition to all of the properties of normal pixels, pixols offer some unique features of their own.

The concept of depth-enabled painting is easier to show than to explain. In the figure below, the square on the left is some simple painting (a couple of strokes) I made on the canvas, using the default settings when ZBrush first starts. Then, in the middle of the figure, you can see exactly the same 'drawing', but with just the lighting changed. Because parts of the canvas have been raised, the direction of lights affect how things appear on the canvas. Yes, ZBrush provides lighting control, and it can be used to change the look of a painting without making a single brush stroke! Finally, on the right I pulled a little trick by converting the canvas to a polymesh, and then rotating that polymesh to show the depth of the original canvas. (There's no actual way of 'rotating' the canvas to see it from a side view.)

And by the way...painting with depth is really important in modeling, because it's how you add the finest level of detail to ZBrush models.

Clipping Planes

Once we allow painting with depth, we have the question–how 'deep' is the canvas, i.e. how near is the nearest point, and how far is the farthest point. Just like width and height, which must be finite for any image, so must depth.

In ZBrush, the range of depth of the canvas is fixed; you can't change it, unlike width or height. However, the range of depths is quite large (over 65,000 possible planes on which a pixol can be), so that's unlikely to be a problem.

Within all of those planes along the z-axis, three are of particular importance:

• The back plane is at the farthest distance at which a pixol can be drawn.
• The front plane is at the nearest distance at which a pixol may be drawn.
• The canvas plane is midway between the back and front planes. When you first start ZBrush, all the gray pixols you see on the canvas are at the distance of the canvas plane.

Material-Enabled Painting

Guess what–not only can you paint depth in ZBrush, but you can paint Materials too. A material in ZBrush is like a material in other programs that provide shaders. It can produce surface effects like wood grain, metalicity, glow, and so on. The difference is that in ZBrush, materials can be applied not just to models, but also to pixols on the canvas itself.

Here's a canvas that's been painted with just a couple of strokes. One was done with a reflective material (using a picture for an environment map), another with a 'rough metal' surface, and the final with a 'gel' material. All of the complex surface appearance is due to the material. None of it is due to the painter (me), who couldn't paint such effects if my life depended on it anyway.

These paint strokes were done with depth-painting enabled, so they raised portions of the canvas. Especially with the reflective stroke, you can really see how the material and the depth of the canvas come together to create the final effect.

Alphas

Alphas are another big part of the painting equation. An alpha is simply a gray map, and it can be used to affect lots of things. Alphas can represent depths, masks, transparencies, and virtually any effect that depends on intensity. 3D maps such as cavity and bump maps are really just alphas.

ZBrush comes with a bunch of predefined alphas, that can be found in the alphas popup; either to the left of the canvas, or in the Alpha Palette. It's also easy to create or import your own alphas, but we won't go into that, because it's not really part of how alphas affect painting.

The major effect of alphas is to modify the shape of the brush. Basically, gray parts of an alpha mean the brush has less effect, and white parts of the alpha mean it has more effect. (Dark area mean it has an 'opposite' effect.)

Let's show this with a bit more depth painting. In the figure below, I just started up ZBrush, and 'clicked' three paint strokes. (I didn't drag them out or anything like that.) All of the ZBrush settings were left at their default values except for the alpha.

The stroke at the left shows the effect of the default alpha (Brush 01). Since that alpha is an image with white at the center, fading to gray at the outside, we get an effect where the center of the clicked stroke is raised, and the area around it fades smoothly into the depth of the rest of the canvas.

The center of the image shows the effect when using alpha Brush 17, the 'bullseye'.

Finally, the right of the image shows the effect of a more interesting alpha, Brush 30 I think of this as the "soccer ball" alpha.

Strokes

There's yet another factor in the ZBrush painting equation, strokes. A stroke can be thought of (more or less) as controlling brush movement.

To get an idea of what strokes do, let's consider some of the simpler strokes.

• The Dot stroke places a single dot on the canvas, with a twist. If you click and hold the mouse with this stroke active, you can drag the stroke around to position it. It's finalized once you release the mouse button. Very useful!
• The Dots stroke applies a series of dots as you drag the mouse along. It's as if you clicked on one point, and then clicked on another point a littler farther away, and so on. The dots are put down at regular intervals of time, so the faster you move your mouse, the farther away the dots will be from one another.
• The Freehand stroke corresponds to a 'standard' stroke in other programs–or on a real, physical canvas, for that matter. It lays down a continuous layer of paint, depth, and material on the canvas as you move the mouse along. This is actually done by putting down 'dots' at very closely spaced intervals, and you'll be able to see this with complex alphas.

But there are more complex strokes. Two examples are are:

• The Grid stroke effectively makes multiple copies of a dot stroke, and moves them outwards in a grid from where you drag, according to how far you drag the mouse.
• The Spray stroke puts down multiple semirandom copies of your basic brush, around the mouse, as you move the mouse.

Examples of the stroke types described above can be seen in the figure below. But there are more stroke types than this!

The Picker Palette

I know you're already feeling a little buried, but there's still another thing we need to consider. The good news is that it's something you can more or less ignore for much of what you do, especially when you're first starting to use ZBrush. The other good news is that when you do use it, it can do some really cool stuff. The bad news is that since it isn't obvious how useful it is, you may forget about it. That's the Picker Palette.

Basically the Picker Palette affects how the pixol under the brush affects the paint stroke. This is discussed at some length in the Picker Palette, so we won't go into details here. Instead, we'll just look at one of the options the picker palette offers.

Let's say you start a paint stroke on the canvas, and you drag it over other, existing strokes. All of these strokes have depth, so we need to figure out how the new stroke will interact with existing strokes:

• Will it be hidden or partly hidden by the existing strokes?
• Will it maintain a constant depth, or will its depth change as it moves over canvas areas with differing depths?

The Picker Palette lets us choose such options. In the case described above, we can choose to have the new stroke continue at the same depth it started at, or follow the depth of the underlying content, and so always remain "on top of" whatever already existed. And there are several other related options, as well.

Again the Picker Palette talks about these options in detail. Please look there for more information.

Basic Controls

We've left discussion of the most basic painting controls until now, because many of them don't make sense unless you understand things like alphas, or painting with materials. These controls affect many or most aspects of painting (or sculpting too, for that matter). For convenience, they are grouped together above the canvas:

They can also be found in their 'real' homes, the xxx....

And here's what they do:

• A number of buttons control what effects are applied to the canvas when painting. Mrgb means use the selected material and color when painting, Rgb means use color but not material, and M means use material but not color.
• When depth painting is on, Zadd means that light area of an alpha pull pixols towards the viewer, while Zsub means light areas of an alpha push pixols away. (But it's normally more convenient to just just one of these, and hold down the 'xxx' key to invert it's meaning.) Zintensity affects how much pushing or pulling is done with each brush stroke. (A useful tip; for most uses, keep Zintensity small, and use repeated brush strokes to do what you want to do.)
• The Brush chooser, Material chooser, Alpha chooser, Tool (paintbrush) chooser, Stroke chooser can all be found on the area to the left of the canvas. Oh, the Color chooser (foreground and background) can be found there too. These choosers can also be found in individual palettes: xx.

Models as Paint Strokes (and Paint Strokes as Kinda Models)

If you've looked at the ZBrush Tool inventory, you'll have noticed the usual complement of brushes–simple brushes, airbrush, eraser, and so on. But you'll also have seen that 3D models are part of this inventory. (All of ZBrush's 3D primitives are there, and any imported models will show up also.)

ZBrush can paint using models (and can also treat more traditional paint strokes as models in some ways, as we'll see in a moment). After all, a paint stroke is just a movement of the mouse that affects pixols on the canvas–and laying a model down on the canvas certainly comes under that heading.

Here's a canvas where I've drawn in some models along with some more basic strokes. Except for the last stroke I drew, all of these strokes are 'fixed' on the canvas. The most recent paint stroke you drew is called the live stroke, and you can do certain things to it, but previous painting becomes fixed to the canvas; you can't remove except via undo operations. (However, you can keep different strokes on different Layers, to make it easy to modify some but not others.)

Placing Models and Strokes

Drawing 3D models onto the canvas wouldn't be very useful unless you could place them right where you wanted them–rotate them, move them into place, shrink or grow them. When you draw a model, it becomes the live stroke (the most recent stroke put on the canvas), and can be placed using the xxx buttons.

When any of these button are active, a neat-looking little control called The Gyro appears around the model. Clicking on different parts of (or outside or inside) the gyro will move, scale, or rotate the model in different ways, depending on which of move/scale/rotate is on.

Now for something very cool. Using the gyro, you can place almost any stroke, not just models.

Below on the left is a crude 'Z' drawn with the basic simple brush. Second from the left, I've activated rotate mode; the rotate gyro appears at the center of the stroke. And in the next two snapshots, you can see the 'Z' stroke rotated by different amounts and in different directions. ZBrush can move, scale, or rotate strokes, even along the z-axis, regardless of whether or not they are models..

Putting It All Together

Whew! Quite a collection, eh? Let's look at all the things that can affect a single brush stroke:

• Choice of paint brush.
• Foreground (and maybe background) color.
• Depth settings (enabled/not enabled, intensity, and others).
• Alphas.
• Materials.
• Stroke setting.
• Picker palette.

Altogether, these properties give you a great deal of control over what your painting does in ZBrush. But, as any Jedi master could tell you, with Great Power comes Great Responsibility, and Great Danger. In particular, you may find at some times that your painting isn't doing what you think it should be doing. What to do?

Well, first be aware that ZBrush remembers certain settings, associated with other choices, xx.

So, when things aren't behaving as you expect, check everything that might be affecting your painting. You Know What These Are, they're listed above. Experiment with some other brushes, to see if that helps you track down a forgotten setting.

If things are still really confusing, you may be overlooking a setting. Save your scene and custom tools (including models), quit ZBrush, and restart. No, this isn't a problem with ZBrush–it's just that's so flexible that it's easy forget settings you've changed.

And if all else fails, press xx. This will reset most of ZBrush to be very close to its factory configuration.

Exercises

What would a primer be without exercises at the end? The following diagram shows six effects that were each drawn with just one or two paint strokes. Your task, should you choose to accept it, is to come as close as possible to these effect, regardless of how you do it.

Not everything you need to know to do the above has been talked about explicitly on this page, so here are some hints.

• Many stroke types have additional settings. If you select a stroke type (especially a specialized one), check the Stroke Palette to see if any additional settings show up.
• When you're working with 3D strokes, don't forget to use The Gyro!
• Remember that many brushes need something to paint on, before they can paint. Maybe you need to lay down a patch of square?
• The Roller Brush can be used to paint a color or texture in a continuous strip.
• The Deco Brush texture defaults to a nice rainbow-type spectrum.
• Alphas and textures can work together; one defines what will show up in a paint stroke, the other defines what parts of the pattern will show up.
• There are some neat stroke types we didn't talk about.