2.5D Basics

A Paint Program with a 3D Rendering Engine

Most paint programs only give you color to work with. This means that any attempt to duplicate real-world materials or simulate depth and lighting in an image must be accomplished through meticulous painting or clever use of filters. By comparison, ZBrush actually gives you three channels to work with. Color can come from either the Color or the Texture palette. Material is selected and controlled in the Material palette. Depth is possible with any 3D object, and also with most brushes (which are all selected from the Tool palette). As the illustration to the right shows, your choices then get processed by the real-time rendering engine to create a finished result.

The Draw Palette Controls the Show

Like a conductor orchestrating a performance, the Draw palette controls the ZBrush show. This palette lets you instruct ZBrush how you want it to apply the effects created by the various channels. The MRGB, RGB and M buttons let you tell ZBrush whether to paint with Material, Color, or both. ZADD, ZSUB and ZCUT tell ZBrush how to apply depth. The Intensity sliders let you specify how much color and depth to apply. Other sliders let you modify the size and shape of your brush, add perspective effects, and even simulate refraction. This approach to painting gives you tremendous control! You can, for example, take a Sphere3D and use the Draw palette to flatten it out, then make it transparent and refractive — an instant lens. Or you can use a Spiral3D with depth turned off to paint curley shapes.

In the example below, the same “Z” was repeatedly drawn with only one thing being changed in each column. As you can see, the various palettes work together — all under the direction of the Draw palette — to produce a tremendous variety of effects.


Many of the 2.5D brushes (such as Hue Shifter and Shading Enhancer) only use the color Channel and ignore the Depth or Material channels. You can use these brushes to affect the base color and then allow ZBrush to render the Material and Depth effects. However, there will be times when you want to affect the Shaded (rendered) colors instead of just the Color channel. You can do this by Baking the layer. Pressing Shift+B allows ZBrush to render the layer and then convert all rendered color back into the Color channel. To keep these colors “pure,” the material is converted to Flat Color which is unaffected by the way that lighting interacts with the Depth channel. This means that it is usually best to set up your scene’s lighting before Baking the layer. Special Note: The Draw palette’s Refraction effect will only refract the Color channel. If you want to see rendered colors through a refractive object, you must bake the layer before drawing the object.

The Stroke & Alpha Palettes

The last two columns at the left show even more ways that you can tap into ZBrush’s power. The Alpha palette controls grayscale images that can be used to create unique brush shapes. You can even create or import your own. The Stroke palette, as you might imagine, specifies the way that your stroke behaves from mouse click to mouse release. Use this to draw straight lines, strings of beads, simulate a paint brush, or even introduce chaos. 3D objects use the DragRectangle stroke by default, but you can use any of the other strokes for interesting effects. Some of ZBrush’s most spectacular results are achieved by using these two palettes creatively.