Working With Your Canvas: Strokes

From ZBrush Info

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!

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..