Planar Brushes
The Planar brushes will flatten the mesh based on the direction of the underlying surface normal and the document plane. The depth at which they will carve away form is dependent on the Depth setting under the Brush menu. The Imbed feature will determine how far a Planar brush will begin its depth into the surface (Figure 10.44).
Many of the Planar brushes make use of the new backtrack setting under Stroke + LazyMouse (Figure 10.45). PlanarLine, for instance, allows you to bevel an edge using the Backtrack Line setting (Figure 10.46).
Figure 10.43 This mechanical form study was created entirely using spheres and the Clip brushes.
Figure 10.44 The brush Depth Mask control sets how deep into the surface the Planar brush functions.
Figure 10.45 Planar line used to bevel an edge
Figure 10.46 The new
Backtrack Stroke settings are used by many of the Planar brushes to create unique tools.
The Trim Brushes
The Trim brushes will trim away at the surface while respecting the surface normals and maintaining an edge along the stroke. Only two Trim brushes will respect the document plane (TrimFront and TrimNormal) whereas all others will evaluate the surface normals along your brush stroke. Figure 10.47 shows the Trim brushes in action.
The Polish Brushes
The Polish brushes will respect all edges. The hard edges will be maintained as the stroke is moved along the surface. The surface is relaxed along the stroke to form a flat surface.
The Polish brushes often help support the other hard-surface brushes. Notice how in Figure 10.48 the Polish brushes help refine the transitions between the Trim brush planes. They help to reduce the sharp edges while retaining the sense of structural form in the sculpture.
Backtrack
Backtrack is a new subset of LazyMouse that helps you create straight lines or force your stroke to conform to a path. Backtrack is enabled under Stroke ^ LazyMouse (Figure 10.49). When working with Backtrack, you’ll find it best to turn Track Curvature up. This ensures that the stroke will continue to affect the surface even when it is curvy and not flat to the camera. SnapToTrack forces the stroke to conform to the line or curve you draw. You can turn this off for total freedom in your stroke, but often you want to confine your stroke to the path you draw for accuracy.
The Backtrack options are as follows:
Figure 10.47 The Trim brushes in action
Figure 10.48 The Polish brushes in action
Plane Plane applies a virtual plane to the surface. Anything intersecting this plane will be sliced by the tool.
Line Line constrains the stroke to a straight line. Hold Shift to conform the line to a 45-degree angle as you draw. I will often use Pinch with Backtrack Line and SnapToTrack enabled to create sharp, straight lines on mechanical forms.
Spine Spine conforms the stroke to a smooth curve between the point where you press the pen down and the endpoint.
Path Path conforms the stroke to a user-defined.
Figure 10.49 The Stroke LazyMouse menu with Backtrack on
ShadowBox, Group Loops, and Matchmaker
In addition to the hard-surface brushes, we will use several new tools. We will use ShadowBox to create some mechanical parts. ShadowBox is a new mesh generation tool that allows you to draw an object’s profiles to generate it in 3D space (Figure 10.50). We will also use group loops to help create sharp edges (Figure 10.51). Finally, we will look at Matchmaker for taking one shape and conforming it perfectly against another. This is a fantastic tool for creating ornaments, moldings, and other detailed shapes that need to conform against a surface (Figure 10.52). Before we try to implement these techniques on a new model, let’s explore each of these new tools with some brief exercises.
Using ShadowBox and Group Loops
In this exercise you will use ShadowBox to create new geometry. ShadowBox lets you create new 3D objects by simply drawing their profiles with the masking tools on a three-sided box that represents front, side, and top views. Please be sure to see the accompanying DVD for a video on this process. Let’s get started:
1. Initialize ZBrush to create a new scene. From the Lightbox + Tool menu, select the dog.ztl file.
2. You need to have a subtool before you can enable ShadowBox. Duplicate the dog with Tool + Subtool + Duplicate. Under Tool + Subtool, adjust the Res slider to 200. This will control the density of the meshes created with ShadowBox. Make sure Transparency is on in the sidebar. Now click the Tool + Subtool ShadowBox button to enable ShadowBox (Figure 10.53).
Figure 10.50 ShadowBox allows you to create geometry by drawing.
Figure 10.51 Group loops help you isolate and extrude areas of the mesh, keeping perfectly sharp borders.
Figure 10.52 Matchmaker conforms one shape to another. It’s perfect for housings, molding, and ornate tracery.
3. The ShadowBox will appear. You’ll see that the dog is now converted to a simplified form (Figure 10.54). This is because the ShadowBox will incorporate the current subtool. This allows you to further edit a shape using ShadowBox if you desire. In this case you will create a new shape, so clear the ShadowBox using Ctrl+click-drag. ShadowBox is based on masking, so clearing the mask clears the geometry.
Figure 10.53 The Res slider and the shadow-box button are found under the Tool Subtool menu.
Figure 10.54 ShadowBox will initially try to capture the form of the selected subtool.
4. ShadowBox works by masking. Drawing masks on each of the box faces will define the shape from that view. Hold down Ctrl and draw a mask on the box, as shown in Figure 10.55. You will further refine this shape by drawing it in the other views.
5. Draw a mask on the floor of the box to define the shape from the top view (Figure 10.56). Repeat this for the back face of the box (Figure 10.57). By unmasking areas, you can cut negative spaces into the 3D form (Figure 10.58).
Figure 10.55 Drawing a mask on the box results in 3D geometry created in the shape of the mask.
Figure 10.56 The floor allows you to define the shape from the overhead view.
Figure 10.57 Each face of the box helps further define the shape of the model.
Figure 10.58 Unmasked areas will become negative spaces.
6. When you are done defining your shape, click the ShadowBox button again to exit. The mesh will now be available as a subtool for further sculpting (Figure 10.59). Note that the mesh will be automatically polygrouped in a logical manner.
Figure 10.59 The ShadowBox mesh ready for sculpting. Notice that the model is automatically polygrouped when you exit ShadowBox.
Figure 10.60 The circles on top were moved by using a mask only to isolate the faces. The bottom used group loops. Notice the far better quality of the edges on the bottom model.
You will now use group loops to isolate the polygroups with an edge loop cut by ZBrush. This allows you to mask and move the grouped areas while maintaining razor sharp angles in the mesh. Figure 10.60 shows a masked area of the mesh moved. Notice how the edges are tagged compared to the looped area.
1. Select the Mask Pen brush and, while holding down Ctrl, mask out a section of the side of the object (Figure 10.61). Click Tool + Polygroups + From Masking to create polygroups based on the masked area (Figure 10.62).
2. The edges of this group will be jagged due to the lower poly count of the object. To cut new edge loops around the polygroups, click Tool + Geometry + GroupsLoops (Figure 10.63). Figure 10.64 shows the resulting loops.
Figure 10.61 Mask an area on the side of the object.
Figure 10.62 Polygroup based on masked area. Notice the ragged edges on the polygroup.
Figure 10.63 Click the Tool ^ Geometry ^ GroupsLoops button to cut new edge loops around the polygroups.
3. Ctrl+Shift-click to isolate the circle group. You can then expand to include the loops in your selection by clicking Tool ^ Visibility ^ Grow (Figure 10.65).
4. Mask the selection, then show visibility on the rest of the model. Invert the mask and use Transpose to move the faces out. The resulting transition will be perfectly sharp (Figure 10.66).
That completes the group loops and ShadowBox exercises. You can see how these tools can be invaluable for creating interesting new shapes. ShadowBox is one of the most powerful new additions to ZBrush.
We will now move on to Matchmaker to see another unique tool available in ZBrush 4.
Figure 10.64 The loops cut around the polygroup
Figure 10.65 Grow Visibility will expand your selection to include the edge loops.
Figure 10.66 Moving the unmasked polys creates a sharp transition impossible without group loops.
