NURMS (non-uniform rational MeshSmooth) is one radio button in Mesh-Smooth. NURMS is not defined by a ratio of matheticatical functions, so it is not really “rational.” This is merely a play on the NURBS acronym, because NURMS gives you the option of weighting the vertices of the low-poly model similarly to the weighted CVs of a NURBS model and lets you set different tessellation for the viewport and the renderer.

Let’s try it.

1.  Reset MAX.

2.  Create a box three segments in length, width, and height.

3.  Right-click the perspective viewport label and select Edged Faces.

4.  Click the Edit Stack button and choose Collapse to Editable Mesh.

5.  Apply a MeshSmooth modifier. The box is rounded by the modifier. Notice that the NURMS option is checked as a default.

6.  Check Display Control Mesh further down in the Modify tab. Now you should see an orange gizmo around the object in the exact shape of the original low-poly mesh.

TIP In the Subdivision Amount section, you can set a low value of iterations and smoothness for the viewport, to keep things speedy, and a higher value for rendering, just as in patches and NURBS.

7.  In the modifier stack, select Editable Mesh from the drop-down list to get to the editable mesh level.

8. Click the Show End Result button to show what the mesh looks like after the MeshSmooth is applied.

9.  Click the Polygon Sub-Object button.

10.  Select a polygon (of the low-poly model now visible as a gizmo) and turn up the Extrude spinner under Edit Geometry. You can see the extrusion rounded by the MeshSmooth in the viewport as you do it.

11.  Click the Vertex Sub-Object button.

12.  Move a vertex outwards to see the distortion of the mesh.

13.  With the vertex still selected, scroll down to the Surface Properties selection and turn up the weight of the vertex. It pulls the mesh towards it, just as a CV does in NURBS. Your mesh might look something like Figure 5.35.

	NOTE The Weight parameter is available in Edit Mesh or editable mesh for selected vertices, as well as in the MeshSmooth modifier, but it doesn’t do anything unless you have a MeshSmooth modifier applied with NURMS checked.

FIGURE 5.35  The weight is increased on one vertex of this low-poly model.

Using these techniques, you can continue to develop your low-poly model on the sub-object level and see what the final results will look like on your high-poly model as you do it. You get the advantages of “non-uniform” weighted vertices and separate levels of detail for the viewport and the renderer without the computational costs of NURBS.

Hands-on MAX: Organic Box Modeling

Now that we’ve looked at subdivision surface modeling with NURMS, let’s use it to model a whole character. We will take an approach that we also saw in Chapter 4, called box modeling. This popular technique is sometimes called “cubes and tubes,” because all models begin as either box or cylinder primitives. Applying the Mesh-Smooth modifier makes it an organic subdivision surface model, but remember that you can always strip off the modifier and have a low-poly model suitable for games.

The basis of this process is to edit a simple cube primitive using various right-click menus (shortcut menus) that are new in MAX R3. During the editing process, a Mesh-Smooth modifier will smooth out the simple object into a more natural-looking model. You’ll be able to observe this smoothing effect while you are editing the simple geometry making up a base object. This builds upon the subdivision surface modeling of the shark, but primarily uses right-click menus to speed up the workflow.

Creating the Base Object

1.  Reset MAX.

2.  Under Create Ø Geometry Ø Standard Primitives, select Box.

3.  Create the cube in the perspective viewport with length, width and height values all 10.

4.  Select the Move tool and then immediately right-click its icon. The Move Transform dialog box will appear.

5.  In the Absolute:World section, enter zero for the X, Y, and Z values. This will ensure that the cube just created will be at the center of the scene. Close the dialog box.

6.  Select Zoom Extents All from the Viewport Controls.

7.  In the perspective viewport, right-click the label and select Edged Faces while leaving Smooth + Highlights active.

The previous step will retain the smooth shading, but will now also show the edges of the object’s polygons in the shaded viewports. This will help clarify where you are performing edits later in the exercise.

8.  Apply a MeshSmooth modifier with default values to the cube.

9.  In any viewport, right-click the cube and select Convert to Editable Mesh.

This step collapses the cube to a symmetrical and slightly rounded form that will be the basis of the model. You should now have something like Figure 5.36.

FIGURE 5.36  Perspective view of the collapsed “cube”

	NOTE If you want to start from here, you can open the file Organic1.max on the CD.

If you right-click the model again after converting to editable mesh, you will notice that the shortcut menu (Figure 5.37) now offers several more options.

FIGURE 5.37  The editable mesh shortcut menu

Since most characters are roughly symmetrical in nature—that is, their right and left halves are basically mirror copies of one another—you will only need to worry about modeling half of the character. Later you will copy, attach, and weld a second half to restore the “whole.” This method will give you several advantages. First and foremost, you will only have to work on half the geometry in the viewports, which provides a much cleaner workspace and saves time. Also, your character will end up being perfectly symmetrical. If you do not wish to create a symmetrical character, the methods describe herein will still apply; it will just take a bit more work and care during the modeling process to get your desired results.

10.  Go to the Vertex sub-object level. In the front viewport, select the vertices on the right side of the model.

	WARNING Use the Rectangular Selection Region tool to select all the vertices on the right side of the model. Make sure you do not select the vertices that make up the centerline down the middle. Selected vertices will turn red.

11.  With the right-side vertices of the model active (while in the Vertex sub-object level), hit the Delete key. This will remove these vertices from the model. Turn off the Sub-Object button.

12.  Save or hold your scene.

Adding the Active MeshSmooth

The initial cube object has been created, slightly smoothed, and halved. You will now proceed to apply another MeshSmooth modifier that will display the resulting smoothed mesh, but will enable you to edit the underlying simple geometry.

	NOTE If you want to start from here, you can open the file Organic2.max on the CD.

1.  Apply a MeshSmooth modifier, initially using default parameters.

2.  In the Parameters section of the MeshSmooth modifier, find the Display/ Weighting section and turn on the toggle for Display Control Mesh.

You should notice an orange cage around the smooth, spherical shape. This cage represents the underlying geometry that you will be editing, and is the shape of the object just before the MeshSmooth modifier (relative to the history of the modifier stack).

3.  To demonstrate this effect more clearly, click the icon for Active/Inactive Modifier toggle (found just under the name MeshSmooth). The object will then resemble the Control Mesh activated in step 2.

4.  Click the icon for Active/Inactive Modifier toggle once again. This will restore the MeshSmooth modifier.

You should now have a selection like the one in Figure 5.38.

© 2000, Frol (selection, edition, publication)