Chapter 4

Beginning Polygonal Modeling

Simple objects call for simple models, and complicated objects call for a complex arrangement of simple models. Like a sculptor, you must analyze the object and deconstruct its design to learn how to create it.

The Autodesk® Maya® software primarily uses two types of modeling: polygons and NURBS. Both require a process that begins with deciding how best to achieve your design, although it’s common to mix modeling methods in a scene.

To help you decide where to begin, this chapter starts with an overview of modeling, briefly describing the two popular methods and how they differ. You’ll also learn about primitives. The second part of the chapter takes a detailed look at modeling with polygons. (The next two chapters cover the process of modeling with polygons and NURBS surfaces and how to bring them together in one model.)

• Discern how to better plan your model
• Edit polygon geometry in traditional Maya as well as Modeling Toolkit workflows
• Navigate the Modeling Toolkit interface
• Work with the Modeling Toolkit selection workflow
• Extrude, bevel, and wedge polygons
• Use edge loops to create detail
• Create curves and then use the Revolve function to turn them into polygon meshes
• Adjust grouping and hierarchies in a complex model

Planning Your Model

Dissecting the components of an object into primitive shapes will help you translate and re-create it in 3D terms. You create the elements in Maya and then join them together to form the desired object.

Take reference pictures from many angles, get dimensions, and even write down a description of the object. The more perspectives from which you see your subject, the better you’ll understand and be able to interpret your model.

Decide the purpose for your model. Then, determine the level of detail at which it will be seen in your CG scene. Consider the two scenes in Figure 4-1. If you need to create a park bench that is shown in a far shot (left), it will be a waste of time and effort to model all the details such as the grooves in the armrest. However, if your bench is shown in a close-up (right), you’ll need those details.

Figure 4-1: The level of detail you need to include in a model depends on how it will be seen in the animation.

If you aren’t certain how much detail you’ll need, it’s better to create a higher level of detail rather than skimping. You can more easily pare down detail than create it later.

Keep in mind that you can also add detail to the look of your model in the texturing phase of production, as you’ll see with the decorative box later in the book. (Chapter 7, “Autodesk Maya Shading and Texturing,” covers texturing.)

Choosing a Method

Polygon modeling involves tearing and extruding from larger pieces to form a desired shape. This method is typically preferred by most digital artists in the field.

NURBS modeling is great for organic shapes because the basis of all NURBS surfaces is smooth lines, or curves. However, NURBS tends to be more difficult in comparison since it’s more difficult to create a complete model without several surfaces that must be perfectly stitched together, as you will see in the next chapter. Subdivision surfaces combine the best of both worlds but is not a popular workflow and is largely hidden in the interface now; therefore, it will not be covered in this book. But with subdivision surfaces, an artist can begin with a rough shape, chisel it out coarsely, and then switch to finely detailed sculpting by adding levels of detail to the sculpture only when and where needed. NURBS is covered in the next chapter.

In the end, when using NURBS, converting everything back to polygons is almost always preferable. Why? The available rendering applications all turn everything to polygons (a process called tessellation) when they render the scene. You can save yourself some memory and time and be the master of your own models by trying to go back to polygons as often as is reasonable.

An Overview of Polygons

Polygons consist of faces. A single polygon face is a flat surface made when three or more points called vertices are connected. The position of each vertex defines the shape and size of the face, usually a triangle. The line that connects one vertex to another is called an edge. Some polygonal faces have four vertices instead of three, creating a square face called a quad instead of a triangular one called a triangle.

Polygonal faces are attached along their polygonal edges to make up a more complex surface that constitutes your model (as shown with the polygonal sphere in Figure 4-2). A camping tent is a perfect example. The intersections of the poles are the faces’ vertices. The poles are the edges of the faces, and the cloth draped over the tent’s frame is the resultant surface.

Figure 4-2: A polygonal sphere and its components

Polygon models are the simplest for a computer to render. They’re used for gaming applications, which need to render the models as the game is running. Gaming artists create models with a small number of polygons, called low-count poly models, which a PC or game console can render in real time. Higher-resolution polygon models are frequently used in television and film work. Because even complex polygon models can be made of a single object or mesh, they’re useful for character animation work as well. Models in character animation bend and warp a good deal, so having a single surface that won’t separate at the seams can be advantageous.

Using Primitives

Primitives are the simplest objects that you can generate in Maya (or in any 3D application). Primitives are simple geometric shapes—polygons or NURBS. Typically, they’re used to sculpt models.

Because you can define the level of detail of the primitive’s surface, primitives offer great sculpting versatility through vertex manipulation. You can create polygonal primitives using practically any level of subdivisions to define the number of vertices and faces.

You may find it helpful to analyze your modeling subjects into forms and shapes that fit in with Maya primitives to get a better sense of how to begin a modeling assignment. Figure 4-3 shows all of the primitives in Maya, including NURBS, polygons, and volume primitives. Quite different from geometry primitives, volume primitives are used for lighting and atmosphere effects, such as fog or haze, and don’t play a part in modeling.

Figure 4-3: The Maya primitives

Polygon Basics

Polygon modeling is popular because its resulting models are usually one piece of geometry with many facets. You can, therefore, deform polygon models without fear of patches coming apart, as can happen with NURBS. Polygons, however, have a finite detail limitation and can look jagged up close or when scaled up. One solution to this problem in the Maya software is the Smooth tool.

A popular method of polygonal modeling, sometimes called box modeling, involves creating a base object, such as a simple cube, and then pulling and pushing faces to draw angles to create more faces. Whereas NURBS typically needs the creation of curves to start, complex polygons are usually created from basic-shaped polygons such as primitives.

A second method for creating poly surfaces uses the same curves that NURBS surfaces use or even converts a completed NURBS surface model to polygons. A third method is to create poly surfaces directly with the Polygon tool, which allows you to outline the shape of each face.

Creating Polygonal Primitives

The most notable difference between the options for a NURBS primitive and a poly primitive are the options for surface detail. With a NURBS surface, sections and spans define detail. With a poly mesh, detail is defined by subdivisions, which are the number of rows and columns of poly faces that run up, down, and across. The more subdivisions, the greater definition and detail the mesh is capable of.

Choosing Create ⇒ Polygon Primitives gives you access to the poly version of most of the NURBS primitives. Opening the option box for any of them gives you access to their creation options. To see an example, choose Create ⇒ Polygon Primitives ⇒ Sphere, and open the option box.

To get started, first make sure History is turned on, or there will be no creation node; then, click Create to make the poly sphere. Open the Attribute Editor, and switch to its creation node, called polySphere1. In the creation node polySphere1 (in the option box, these are called Axis and Height Divisions), you’ll find the Subdivisions Axis and Subdivisions Height sliders, which you can use to change the surface detail retroactively.

The Polygon Tool

You use the Polygon tool (switch to the Polygons menu set, and then choose Mesh ⇒ Create Polygon Tool) to create a single polygon face by laying down its vertices. When you select this tool, you can draw a polygon face in any shape by clicking to place each point or vertex. Aside from creating a polygon primitive by choosing Create ⇒ Polygon Primitives, this is the simplest way to create a polygon shape. Figure 4-4 shows some simple and complex single faces you can create with the Polygon tool.

Figure 4-4: Polygon faces created with the Polygon tool

After you’ve laid down all your vertices, press Enter to create the poly face and exit the tool. For complex shapes, you may want to create more than just the single face so that you can manipulate the shape. For example, you may want to fold it.

Figure 4-5: A single-faced polygon with a complex shape

With the surface selected, choose Mesh ⇒ Triangulate. The surface has more faces and edges and is easier to edit, but it’s still simple to create because you start with a single face. If you need a uniquely shaped poly, start with this tool, and then triangulate your surface into several faces, as shown in Figure 4-6.

Figure 4-6: Complex shapes are better with more faces.

Poly Editing Tools

Here’s a brief preview of what to expect in the world of poly editing. You should experiment with each tool on a primitive sphere as it’s introduced, so saddle up to your Maya window and try each tool as you read along.

Later in this chapter, you’ll deploy these new skills. In Chapter 6, “Practical Experience,” you’ll create a cute desk lamp to exercise your modeling skills. For most of the work in this chapter, you’ll use the Polygons menu. Open the Edit Mesh menu, tear it off, and place it somewhere on your screen so you can get a good look at the tools and functions.

Modeling Toolkit

Modeling Toolkit used to be a plug-in called NEX that is now integrated with Maya 2014. It integrates component-level selection and editing tools (such as selecting vertices, edges, faces, etc., and extruding them, for example) together for a more streamlined modeling workflow. Modeling Toolkit can make tedious modeling chores much easier, especially for advanced modeling techniques. I will be covering some of the Modeling Toolkit workflow and how it’s integrated into Maya 2014 alongside Maya traditional workflows, to give you a comparison and allow you to decide which workflow suits you. You’ll take a look at the Modeling Toolkit and its interface later in the chapter.

The Poly Extrusion Tools

The most commonly used poly editing tool has to do with extrusion. You can use Extrude to pull out a face or an edge of a polygon surface to create additions to that surface. You access the tool at Edit Mesh ⇒ Extrude. Maya distinguishes between edge or face extrusion based on whether you’ve selected edges or faces. Follow these steps:

Figure 4-7: Extruding several faces at once on a sphere. The left image shows the selected faces, the middle image shows those faces extruded, and the right image shows those faces extruded with a rotation and smaller scale.

You can also use the direction and shape of a curve to extrude faces. Create a curve in the shape you want your extrusion to take, select the curve along with the face(s), and choose Extrude . Taper decreases or increases the size of the face as it extrudes. Twist rotates the face as it extrudes, and Divisions increases the smoothness of the resulting extrusion. Choose Selected for the Curve setting. When you have your settings for those attributes, click the Extrude button (see Figure 4-8).

Figure 4-8: Extruding a face along a path curve

This seems to be strange behavior, but the Twist and Taper values are taken into account in the extrusion. You can edit these values when you uncheck, or you can reselect this option after you enter values for Twist and Taper. If your faces aren’t extruding to the shape of the curve, increase the number of divisions.

Modeling Toolkit and Extrusions

Modeling Toolkit makes selecting and editing polygonal components more streamlined, making some workflows faster by incorporating tools into one place for ease of access as well as by reducing the amount of times you have to exit one tool or mode and enter another one. Since a lot of what Modeling Toolkit does centers around component selections, let’s start there first.

Modeling Toolkit Interface

By default, the Modeling Toolkit plug-in should be enabled, which places the Modeling Toolkit menu on the Main Menu bar. If you don’t see Modeling Toolkit, simply choose Window ⇒ Setting/Preferences ⇒ Plug-In Manager. About halfway down the list, you should see ModelingToolkit.dll. Check Loaded and Auto Load, as shown in Figure 4-9.

Figure 4-9: Loading the Modeling Toolkit plug-in, if needed

Modeling Toolkit also places an icon on your status bar, next to the XYZ input fields, shown next to the cursor and already turned on in Figure 4-10. When the Modeling Toolkit icon is turned on, Modeling Toolkit is automatically invoked whenever you enter into component selection mode. Go ahead and click the icon to turn Modeling Toolkit on if it isn’t already.

Figure 4-10: The Modeling Toolkit icon button

In addition, Modeling Toolkit places a tab in the Channel Box, called Modeling Toolkit, to make displaying its tool set easier, as shown in Figure 4-11. You will notice toward the top of the Modeling Toolkit panel four icons for selecting, moving, rotating, and scaling. These operate in exactly the same way as transformation tools; however, they enable the Modeling Toolkit functionality. You’ll see this in action throughout the book and introduced next.

Figure 4-11: The Modeling Toolkit panel and tab

Modeling Toolkit Extrusion

Now that you have a little background on how Modeling Toolkit integrates with Maya 2014, let’s use it in comparison to the Maya Extrude tool you just used on a sphere.

1. Make sure the Modeling Toolkit icon () in the status bar is active to see the Modeling Toolkit tab alongside the Attribute Editor and Channel Box/Layer Editor tabs. Then make sure the Modeling Toolkit button in the upper-right corner of the Modeling Toolkit is activated () so that it is lit blue.

2. Create a polygon sphere, and press 5 for Shaded mode.

3. Right-click the sphere in your scene, and select Face from the marking menu for face selection mode. This is the easiest way to select components in Maya, which also works the same while using Modeling Toolkit.

4. Your faces are now highlighting differently than they do in Maya, as you saw when modeling the decorative box in Chapter 3, “The Autodesk Maya 2014 Interface.” Now Modeling Toolkit selection turns the face dark red with a bold red highlight, instead of amber shading. Click a face to select it, or hold down Shift to select multiple faces. As soon as you click to select, the selected faces turn into the familiar Maya amber coloring while in Shaded mode. Select two faces side-by-side on the sphere.

5. In the Modeling Toolkit panel, click Extrude under the Mesh Editing Tools heading, as shown in Figure 4-12. The options appear below the button.

Figure 4-12: Click Extrude in the Modeling Toolkit panel.

Figure 4-13: Click and drag to set the extrusion amount.

Figure 4-14: Modeling Toolkit extrusion in action

Figure 4-15: Keep Faces Together is turned off.

All of these extrusion options and settings are available in the Maya Extrude tool but are a little more streamlined and integrated in the Modeling Toolkit workflow. Experiment to see how you like to work. You will be using a combination of traditional Maya and Modeling Toolkit workflows throughout the chapter and other parts of the book.

The Wedge Face Tool

Similar to extruding faces, Wedge Face pulls out a poly face, but it does so in an arc instead of a straight line. For this tool, you need to select a face and an edge of the selected face for the pivot point of the corner. Here’s how to do this. First deactivate Modeling Toolkit by clicking the icon () to turn off the blue light.

Select a face, Shift+select one of its edges, and choose Edit Mesh ⇒ Wedge Face . (To select a face and Shift+select an edge, right-click the sphere to display the marking menu. Choose Face, and select a face. Right-click again, and choose Edge on the marking menu. Then, Shift+select one of the face’s edges.)

In the option box, you’ll notice some help for the tool under the Description heading. Under the Settings heading, you can select the degree of turn in the Arc Angle (90 degrees is the default) as well as the number of faces used to create the wedge (by moving the Divisions slider), as shown in Figure 4-16.

Figure 4-16: Executing a Wedge Face operation on a face of a sphere

To access selection filters more easily, you can right-click an object to display a marking menu. Drag the cursor in the direction of the selection type you want, and release the mouse button. Then, click or Shift+click your selection.

The Wedge Face tool is useful for items such as elbows, knees, archways, and tunnel curves.

The Poke Face Tool

Poke Face is great for creating detailed sections of a mesh (poly surface) and bumps or indentations. To use the Poke Face tool to add detail to a face, select a face and then choose Edit Mesh ⇒ Poke Face.

A vertex is added to the middle of the face, and the Move Manipulator appears on the screen, as shown in Figure 4-17. This lets you move the point to where you need it on the face. You can add bumps and depressions to your surface as well as create regions of extra detail. By selectively adding detail, you can subdivide specific areas of a polygon for extra detailed work, leaving lower poly counts in less-detailed areas for an efficient model.

Figure 4-17: Poke Face helps create areas of detail in your model.

The Bevel Tool

Use the Bevel tool to round sharp corners and edges. The Bevel tool requires that you select an edge or multiple edges and then use them to create multiple new faces to round that edge or corner.

Select an edge or edges, and choose Edit Mesh ⇒ Bevel to adjust your bevel. The Width slider sets the distance from the edge to the center of where the new face will be. This basically determines the size of the beveled corner. The Segments number defines how many segments are created for the bevel: the more segments, the smoother the beveled edge. Leaving Segments at 1 creates a sharp corner (see Figure 4-18).

Figure 4-18: Increase Segments to create a rounder corner.

The setting of the Roundness slider specifies the roundness of the corner. Setting the number too high will make the beveled edge stick out, as shown in Figure 4-19, although that can be a valid design choice. You can allow Maya to set the roundness automatically based on the size of the geometry being beveled. Select the Automatically Fit Bevel To Object check box to disable the Roundness slider. Move the Segments slider to set the number of new faces that are created on the bevel: the more segments, the smoother the bevel.

Figure 4-19: A poly bevel’s roundness set too high

Use the Bevel tool to round polygonal edges. You can also use it to add extra surface detail, because Bevel creates more faces on the surface.

Modeling Toolkit Bevel

Just like the Maya Extrude and the Modeling Toolkit Extrude, there is a way to bevel inside Modeling Toolkit. Using the same example as earlier, a simple cube, you’ll see how to bevel in the Modeling Toolkit here:

1. With the Modeling Toolkit Activate icon () turned off for traditional Maya workflow, enter edge selection mode by right-clicking a polygon cube in your scene and selecting Edge from the marking menu. When you move your mouse over an edge, it turns red, allowing you to select it. You don’t need to select any edges right now. Now let’s see how it works in Modeling Toolkit.

2. Turn on the Modeling Toolkit icon, and you’ll remain in edge mode. Modeling Toolkit turns the edge red before you select it. However, this time, edges select when your cursor is near them and not directly on top of them as in traditional Maya selection. This feature is one way where Modeling Toolkit improves the speed of modeling in Maya, allowing you to more easily and quickly select components without having to be right on top of them. This is true for vertices as well. You’ll stay in Modeling Toolkit for this exercise.

3. Select an edge on the cube. Press W for the Move tool. You can also select Move from the Modeling Toolkit panel, but the traditional Maya hotkey of W works the same while in Modeling Toolkit. But because you have Modeling Toolkit enabled, your manipulator will have three circles added. Click and drag any of the circles to see that you can move that edge in any two-dimensional plane easily. Moving your mouse over any of the circles gives you the plane axes (Figure 4-20). Undo any moves you may have done, and you’ll move on to the Modeling Toolkit Bevel command next.

Figure 4-20: Modeling Toolkit adds easy planar movement to components with its three circles in the manipulator.

Figure 4-21: The Modeling Toolkit Bevel is the same as the Maya Bevel shown in Figure 4-18.

As you can see, using Modeling Toolkit makes the Bevel tool slightly easier and faster to accomplish with the same result as the Maya Bevel. As a matter of fact, Modeling Toolkit is only a workflow plug-in. It passes all of its changes and work into standard Maya attributes and nodes, making sharing files created using Modeling Toolkit workflow no different from ones created without Modeling Toolkit enabled. So, the cube you bevel in Modeling Toolkit is precisely the same as the one beveled in Maya software’s traditional workflow. The attributes and history on that object are the same.

Putting the Tools to Use: Making a Simple Hand

Starting with a simple polygonal cube, you’ll create a basic human hand using a mix of Maya and Modeling Toolkit workflows.

Either create a new project called Poly_Hand or download the entire project from the web page (www.sybex.com/go/introducingmaya2014) and use that. Follow these steps:

Figure 4-22: The poly cube in position to make the hand

3. Turn on the Modeling Toolkit icon () in the status bar. Click the Modeling Toolkit tab in the Channel Box to see the Modeling Toolkit tools if you need them. Right-click the cube and choose Face from the marking menu.

4. Select the front face that is in the corner closest to you. You’ll extrude the face to make the first part of the index finger. Before you extrude, though, rotate the face a bit in the Y-axis, away from the rest of the hand, to angle the extrusion toward where the thumb would be.

5. In the Modeling Toolkit panel, click the Extrude button. Set Divisions to 3. Click the Local Z radial button, and click and drag in the view panel until the Extrude Local Z readout in yellow reads about 1.1. Exit the Extrude tool. Figure 4-23 shows the full index finger with the slight rotation away from the hand.

Figure 4-23: The index finger

Figure 4-24: Four fingers

Table 4-1: Extrusion length guide

Figure 4-25: A smoothed preview of the hand, with the original shape shown as a cage

Figure 4-26: A full smooth preview of the hand

Figure 4-27: Creating an elongated face for the thumb

Figure 4-28: Select the face and edge for the Wedge Face function.

9. In the Main Menu bar, choose Edit Mesh ⇒ Wedge Face . In the option box, set Arc Angle to 65 and set Divisions to 5. Click Wedge Face. With that wedged face still selected, scale it down in the X-axis to just under half its width to make it less broad, and rotate it toward the hand a bit so it looks like the first image in Figure 4-29.

Figure 4-29: Rounding out the side for the thumb

Figure 4-30: Better-proportioned fingers and knuckles

14. To add more detail to the hand, you’ll raise the knuckles. You need to create new vertices for the knuckles where each finger meets the hand. Enter edge selection mode with Modeling Toolkit still active. In the Modeling Toolkit panel, click the Multi-Cut icon (). Click and drag along the edge between the thumb and the index finger, right below where the index finger attaches to the hand, until the yellow readout reads about 65%, as shown on the left of Figure 4-31. Release the mouse button to lay down the first point of the Multi-Cut operation.

Figure 4-31: Start a Multi-Cut operation on the hand for the knuckles (left). Continue the cut across the first face (right).

Figure 4-32: Adding a cut line across the hand for the knuckles with the Multi-Cut tool in Modeling Toolkit.

Figure 4-33: Use the Poke Face tool to raise the knuckles.

18. Now that you have a simple hand, you can smooth out the mesh to make it less boxy. In Object mode, select the hand, and press 2 to see a preview of what the hand will look like after it’s smoothed. Press 1 to exit the smooth preview. Choose Mesh ⇒ Smooth ; in the option box, set Division Levels to 2, and leave the other options at their defaults (see Figure 4-34).

Figure 4-34: Set the options for the Smooth operation.

Figure 4-35: The smoothed hand with all its history nodes

Save your file again. To verify that you’ve been working correctly, you can load the finished hand file (with its history intact): poly_hand_v3.mb from the book’s web page, www.sybex.com/go/introducingmaya2014.

Creating Areas of Detail on a Poly Mesh

As you saw with the hand, it became necessary to add more faces to parts of the surface to create various details. The hand takes on better form when you devote time to detailing it. You began the hand shown in Figure 4-36 using the previous steps, but you detailed it by creating faces using the tools discussed in this section, moving vertices, and adding fingernails. Don’t expect to be able to model intricately right from the start unless you already have modeling experience. Start with simple objects, work your way up, and stay with it.

Figure 4-36: This detailed hand can be modeled in polygons, given a ton of time and love.

Maya provides several ways to add surface detail or increase a poly’s subdivisions.

The Add Divisions Tool

You can use the Add Divisions tool to increase the number of faces of a poly surface by evenly dividing either all faces or just those selected. Select the poly surface face or faces, and choose Edit Mesh ⇒ Add Divisions. In the option box, you can adjust the number of times the faces are divided by moving the Division Levels slider. The Mode drop-down menu gives you the choice to subdivide your faces into quads (four-sided faces, as on the left of Figure 4-37) or triangles (three-sided faces, as on the right in Figure 4-37).

Figure 4-37: The Mode drop-down menu of the Add Divisions tool lets you subdivide faces into quads or triangles.

You can also select a poly edge to divide. Running this tool on edges divides the edges into separate edges along the same face. It doesn’t divide the face; rather, you use it to change the shape of the face by moving the divided edges, as shown in Figure 4-38.

Figure 4-38: Dividing edges

You use the Add Divisions tool to create regions of detail on a poly surface. This is a broader approach than using the Poke Face tool, which adds detail for more pinpoint areas.

Modeling Toolkit Multi-Cut Tool

As you saw when creating more faces and edges for the hand’s knuckles in the previous exercise, Modeling Toolkit’s Multi-Cut tool allows you to lay down edges along faces fairly easily. This tool (which turns your cursor into a knife shape) is essentially the same as the Interactive Split tool that you used on the decorative box exercise in Chapter 3 (and mentioned in the following section), but it’s rolled into the Modeling Toolkit workflow for ease. It is accessed when Modeling Toolkit is enabled and through the Modeling Toolkit panel under the Mesh Editing Tools heading. You can also make multiple cuts on the same face, as shown in Figure 4-39.

Figure 4-39: The Modeling Toolkit Multi-Cut tool

The Interactive Split Tool

Another way to create detail is to use the Interactive Split tool, which does exactly what its name suggests. As you saw with the decorative box in Chapter 3, when you choose Edit Mesh ⇒ Interactive Split Tool , your cursor changes to a triangle and the option box opens (Figure 4-40). Set Magnet Tolerance to 0 as shown. Use the triangle cursor to select two points along two edges of a face. Doing so creates a line from the first to the second point, which serves as a new edge to divide that face into two halves. You can right-click to commit the new division or continue to create more splits on the same mesh, as shown in Figure 4-40. The Magnet Tolerance attribute allows you to snap the Interactive Split tool along the edge, for example, to the corners or middle of the edge. Again, simply right-click to commit the new division to the face(s). The tool remains active, so you can continue to split faces until you switch to another tool, such as by pressing W for the Move tool.

Figure 4-40: Splitting a polygon allows you to draw the new edge(s) to split the face.

Using the Interactive Split tool is a flexible, accurate, and fast way to create surface subdivisions for your model.

The Insert Edge Loop Tool

This handy tool adds edges to a poly selection, much like the Interactive Split tool, but it does so more quickly by working along the entire poly surface, along common vertices. The Insert Edge Loop tool automatically runs a new edge along the poly surface perpendicular to the subdivision line you click, without requiring you to click multiple times as with the Interactive Split tool or Modeling Toolkit Multi-Cut. You used this tool in the decorative box in Chapter 3 and will continue using it throughout this book. You’ll find it indispensable in creating polygonal models because it creates subdivisions quickly.

For instance, subdividing a polygonal cube is quicker than using the Interactive Split tool. With a poly cube selected, choose Edit Mesh ⇒ Insert Edge Loop Tool. Click an edge, and the tool places an edge running perpendicular from that point to the next edge across the surface and across to the next edge, as shown in Figure 4-41. If you click and drag along an edge, you can interactively position the new split edges.

Figure 4-41: Using the Insert Edge Loop tool

The Offset Edge Loop Tool

Much like the Insert Edge Loop tool, the Offset Edge Loop tool inserts not one but two edge loop rings of edges across the surface of a poly. Edges are placed on either side of a selected edge, equally spaced on both sides. For example, create a polygon sphere and select one of the vertical edges, as shown in Figure 4-42. Maya displays two dashed lines on either side of the selected edge. Drag the mouse to place the offset edge loops, and release the mouse button to create the two new edge loops.

Figure 4-42: The Offset Edge Loop tool

The Offset Edge Loop tool is perfect for adding detail symmetrically on a surface quickly.

Modeling Toolkit Connect Tool

Very similar to the Insert Edge Loop tool is the Modeling Toolkit Connect function. While in Modeling Toolkit, simply select an edge, and click the Connect button in the Modeling Toolkit panel. This will create edges going around the object perpendicular to the selected edge. The Slide attribute places the perpendicular cut along the selected edge, which is slightly less interactive than Insert Edge Loop. However, the Segments attribute allows you to insert more than one ring of edges, while Pinch spaces those extra segments evenly (Figure 4-43).

Figure 4-43: Modeling Toolkit Connect tool creates edges much like Insert Edge Loop.

Modeling Toolkit Raycast Selection and Bridge Tool

One of Modeling Toolkit’s nicest features is its Raycast selection mode. This allows you to essentially “paint” the components you want to select with your cursor instead of having to click every component.

Figure 4-44: Create a subdivided box.

Figure 4-45: Raycast+select a six-face square on the front of the box.

Figure 4-46: Delete the square shapes out of the box.

Figure 4-47: Select these edges (left), and bridge them (right).

Figure 4-48: Bridge the bottom faces.

Experiment with the Divisions attribute for the Modeling Toolkit Bridge to get a curvature in the bridged faces.

Modeling Toolkit Symmetry Selections

One of the charms of Modeling Toolkit is its ability to select in symmetry, meaning the components you select on one side of a surface are automatically selected on the other side as well, making modeling appreciably faster. While Maya has its own Reflection feature in the transformation tools (Move, Rotate, Scale) covered in Chapter 3, it is limited to simple transforms. Tools such as Extrude or Bevel will not work in Reflection mode. Let’s see how Modeling Toolkit Symmetry works.

Figure 4-49: Turn on Symmetry mode.

Figure 4-50: Selecting faces on one side selects them on the other.

Now if you engage any poly editing function, it will act on the symmetrically selected components.

The Combine and Merge Functions

The Combine function is important in cleaning up your model and creating a unified single mesh out of the many parts that form it. When modeling, you’ll sometimes use several different polygon meshes and surfaces to generate your final shape. Using Combine, you can create a single polygonal object out of the pieces.

The Merge tool is important when you’re creating a polygon model because it fuses multiple vertices at the same point into one vertex on the model. Frequently, when you’re modeling a mesh, you’ll need to fold over pieces and weld parts together. Doing so often leaves you with several vertices occupying the same space. Merging them simplifies the model and makes the mesh much nicer to work with, from rigging to rendering.

In the following simple example, you’ll create two boxes that connect to each other along a common edge and then combine and merge them into one seamless polygonal mesh. To begin, follow these steps:

Figure 4-51: Place two polygonal cubes close to each other.

Figure 4-52: Extrude the bottom edge to create a flange.

3. Select the first corner vertex on the newly extruded face, and snap it into place on the corner vertex of the other cube, as shown in Figure 4-53. Remember, you can click the Snap To Points icon () to snap the vertex onto the cube’s corner.

Figure 4-53: Snap the first corner vertex to the newly extruded face.

Figure 4-54: Snap the other corner vertex.

Figure 4-55: There are still two different vertices at the corner, and the boxes aren’t really connected.

Figure 4-56: The cubes are now connected properly at the corners.

You’ll notice fewer errors and issues with clean models when you animate, light, and render them. Combining meshes makes them easier to deal with, and Merge cuts down on unwanted vertices.

The Cut Faces Tool

The Cut Faces tool lets you cut across a poly surface to create a series of edges for subdivisions, pull off a section of the poly, or delete a section (see Figure 4-57). Select the poly object, and choose Edit Mesh ⇒ Cut Faces Tool. Click the option box if you want to extract or delete the section.

Figure 4-57: The Cut Faces tool can be used to create the edges, pull apart the poly object, or cut off a whole section.

You can use the Cut Faces tool to create extra surface detail, to slice portions off the surface, or to create a straight edge on the model by trimming off the excess.

The Duplicate Face Tool

Select one or more faces, and choose Edit Mesh ⇒ Duplicate Face to create a copy of the selected face(s). You can use the Manipulator that appears to move, scale, or rotate your copied face(s).

The Extract Tool

The Extract tool is similar to the Extrude tool, but it doesn’t create any extra faces. Select the face(s), and choose Mesh ⇒ Extract to pull the faces off the surface (see Figure 4-58). If the Separate Extracted Faces option is enabled, the extracted face will be a separate poly object; otherwise, it will remain part of the original.

Figure 4-58: Pull off the faces.

This tool is useful for creating a new mesh from part of the original mesh you are extracting from. You can also use the Extract tool to create a hole in an object and still keep the original face(s). When you use this tool with the Interactive Split tool to make custom edges, you can create cutouts of almost any shape.

The Smooth Tool

The Smooth tool (choose Mesh ⇒ Smooth) evenly subdivides the poly surface or selected faces, creating several more faces to smooth and round out the original poly object.

The Sculpt Geometry Tool

You can use a Maya feature called Artisan to sculpt polygonal surfaces. Artisan is a painting system that allows you to paint attributes or influences directly onto an object. When you use Artisan through the Sculpt Geometry tool, you paint on a polygon surface to move the vertices in and out, essentially to mold the surface.

To access the tool in polygon modeling, select your poly object and choose Mesh ⇒ Sculpt Geometry Tool .

For more on sculpting, see the section “Using Artisan to Sculpt NURBS” in Chapter 5, “Modeling with NURBS, Surfaces, and Deformers.” The workflow is much the same as for sculpting with NURBS; the only difference when sculpting polygons is that the surface behaves in a slightly different manner when sculpted. If you create a poly with a large number of subdivisions, you’ll have a smoother result when using the Sculpt Geometry tool (see Figure 4-59).

Figure 4-59: The Sculpt Geometry tool deforms the surface.

Modeling a Catapult

This exercise will demonstrate the following polygonal modeling techniques:

• Extrusions and bevels
• Object duplication and mirror geometry
• Boolean operations
• Pivot placement
• The Insert Edge Loop tool
• CV curves and revolved surfaces
• Complex model hierarchy

You’re going to create a catapult in this exercise using nothing but polygons. You’ll use some sketches as a reference for the model. Since this is a more involved object than a hand, it’s much better to start with good plans. This, of course, involves some research, web surfing, image gathering, or sketching to get a feel for what it truly is you’re trying to make.

To begin, create a new project for all the files called Catapult, or copy the Catapult project from the companion website (www.sybex.com/go/introducingmaya2014) to your hard drive. If you do not create a new project, set your current project to the copied Catapult project on your drive. Choose File ⇒ Set Project, and select the Catapult project downloaded from the companion website. Remember that you can enable Incremental Save to make backups at any point in the exercise.

Now, on to modeling a design already sketched out for reference. To begin, study the design sketches included in the Sourceimages folder of the project. These sketches set up the intent rather easily.

In Chapter 8, “Introduction to Animation,” you’ll animate the catapult. When building any model, it’s important to keep animation in mind, especially for grouping related objects in the scene hierarchy so that they will move as you intend. Creating a good scene hierarchy will be crucial to a smooth animation workflow, so throughout this exercise you’ll use the Outliner to keep the catapult’s component pieces organized as you create them.

The Production Process

The trick with a complex object model is to approach it part by part. Deconstruct the major elements of the original into distinct shapes that you can approach one by one. The catapult can be broken down to five distinct objects, each with its own subobjects:

• Base
• Wheels
• Fulcrum assembly
• Winch assembly
• Arm assembly

You will model each part separately based on the sketch in Figure 4-60 and the detailed schematic in Figure 4-61.

Figure 4-60: A sketch of the catapult to model

Figure 4-61: A schematic diagram of the finished model to show you your goal

The Base

The base consists of simple polygonal cubes representing timber and arranged to connect to each other. Keep in mind that in this exercise Interactive Creation for primitives is turned off (select Create ⇒ Polygon Primitives and make sure Interactive Creation is unchecked). Also, in the Perspective view, choose Shading ⇒ Wireframe On Shaded to turn on the wireframe lines while in Shaded mode to match the figures in this exercise.

Creating the Base Objects

To begin the catapult base, follow these steps:

1. ChooseCreate ⇒ Polygon Primitives ⇒ Cube to lay down your first cube. This will be for the two long, broad boards running alongside.

2. Scale the cube to 2.0 in X, 0.8 in Y, and 19.5 in Z. Move it off the center of the grid about two units to the right.

3. Now you’ll add some detail to the simple cube by beveling the sides, using either Modeling Toolkit or traditional Bevel, as I will do here. Select the four edges running on top of the board. In the Main Menu bar, select Edit Mesh ⇒ Bevel . Set Width to 0.1 and Segments to 2, and click Apply. Figure 4-62 shows the resulting board.

Figure 4-62: Create a bevel for the baseboard object.

Figure 4-63: Beveling the bottom edges

Figure 4-64: The long boards at the base

6. Now for the cross braces and platform. Create a poly cube and scale it 7.25 in X, 0.6 in Y, and 3.25 in Z. Place this platform on top of the two beams, at the end of the catapult’s base.

7. With the first board that you beveled, you had a different bevel for the top edges than the bottom and sides. For this board, you’ll have the same bevel width for all edges. Select the cube (not the edges as before), and choose Edit Mesh ⇒ Bevel . Set Width to 0.2 and Segments to 2, and click Bevel (or Apply). Figure 4-65 shows the platform board in place and beveled.

Figure 4-65: The platform board is in place.

Figure 4-66: Cross bracing the base

Using Booleans

You’re going to add some detail as you go along, namely, the large screws that hold the timber together. The screws will basically be slotted screw heads placed at the intersection of the pieces. In this section, you will use Booleans to help create the screw heads.

Booleans are very impressive operations that allow you to, among other things, cut holes or shapes in a mesh fairly easily. Basically, a Boolean is a geometric operation that creates a shape from the addition of two shapes (Union), the subtraction of one shape from another (Difference), or the common intersection of two shapes (Intersection).

Be forewarned, however, that Boolean operations can be problematic. Sometimes you get a result that is wrong—or, even worse, the entire mesh disappears and you have to undo. Use Booleans sparingly and only on a mesh that is clean and prepared. You’ve cleaned and prepped your panel mesh, so there should be no problems. (Actually, there will be a problem—but that’s half the fun of learning, so let’s get on with it.)

First, you need to create the rounded screw head.

Figure 4-67: Use the marking menu to set the selection to Face.

Figure 4-68: Delete the bottom half of the faces.

Figure 4-69: Place the scaled cube over the screw head.

Figure 4-70: Selecting a Difference Boolean

Figure 4-71: The screw head is slotted.

Ngons!

Now if you take a good close look at the screw head, especially where the slot is, you will notice faces that have more than four sides, which makes them Ngons. As I noted earlier in the chapter, faces that have more than four edges may be problematic with further modeling or rendering. This simple screw head most likely will not pose any problems in the application here, but let’s go over how to prevent any problems early on. You will select the potential problem faces (those around the slot) and triangulate them.

Figure 4-72: Select the faces around the slot (left), and triangulate them (right).

Figure 4-73: Place the screw heads on the base and organize your scene.

Save your file, and compare it to catapult_v1.mb in the Catapult project from the companion website to see what the completed base should look like.

The Winch Baseboards

Next to model for the base are the bars that hold the winch assembly to the base. Refer to the sketch of the catapult (Figure 4-60) to refresh yourself on the layout of the catapult and its pieces. Follow these steps:

Figure 4-74: Adding the winch baseboards

Figure 4-75: Modeling Toolkit Extrude the face.

Figure 4-76: Modeling Toolkit Extrude the top out to create an L shape; then move the vertices up to angle the top of the L.

Figure 4-77: Click the switch icon (left) to switch the axis of extrusion (center). Rotate and scale the face to square it (right).

5. Press W to exit the Extrude tool and enter Rotate. Select the end face and rotate it to make it flat vertically, and scale it down in Y-axis to prevent it from flaring upward (Figure 4-77 right).

6. This shape forms half of the braces you need. To create the other half, select the face shown in Figure 4-78 (left) and delete it (press Delete). Enter Object mode, select the mesh, and choose Mesh ⇒ Mirror Geometry . Set Mirror Direction to -Z, and leave the options as shown in Figure 4-78 (right). Click Mirror, and you will have a full bracket.

Figure 4-78: Delete the face (left), and set the Mirror Geometry options (right).

Figure 4-79: The winch’s base completed

The Ground Spikes

The last items you need for the base are the spikes that secure the base into the ground at the foot of the catapult. Follow these steps:

Figure 4-80: MMB dragging the duplicated bracketGroup to another location in the Outliner removes the group from the Winch_baseboard1 group.

Figure 4-81: Position and scale the bracket assembly for the ground spikes (left). Move the vertices to reduce the depth (right).

Figure 4-82: Creating the spike.

Figure 4-83: The completed base

The scene file catapult_v2.mb in the Catapult project from the companion website has the completed base for comparison.

The Wheels

What’s a catapult if you can’t move it around to vanquish your enemies? So now, you will create the wheels. Follow these steps:

Figure 4-84: Place the rear axle.

Figure 4-85: Place brackets to hold the rear axle, and adjust the vertices to make it fit.

Figure 4-86: Insert an edge loop around the end of the cylinder.

Figure 4-87: Taper the ends of the axle.

5. To model a wheel, first you’ll use NURBS curves to lay out a profile to revolve. Go into the front view. Choose Create ⇒ CV Curve Tool , and select 1 Linear for Curve Degree. Since the wheel’s profile will have no smooth curves, you can create a linear CV curve like that in Figure 4-88. It’s important for the design to create three spans for the top part of the curve. Place the pivot point (hold down the D key, or press Insert on a PC or Home on a Mac) about 3/4 of a unit below the curve as shown. This curve will be the profile of the front of the wheel.

Figure 4-88: The profile curve for the wheel

6. Place the profile above the rear axle. To make sure the pivot point for the profile lines up with the center of the axle, turn on Snap To Points (a.k.a. Point Snap) (), and press and hold down D to move the pivot. Snap the pivot to the center of the axle, as shown in Figure 4-89. Turn off the Point Snap.

Figure 4-89: The profile curve is in place for the rear wheel.

7. Switch to the Surfaces menu set (Figure 4-90). Select the curve and revolve it by choosing Surfaces ⇒ Revolve . In the option box, set Axis Preset to X to make it revolve correctly. Change Segments from the default 8 to 20 to give a smoother wheel. Set Output Geometry to Polygons, and set Tessellation Method to Control Points. This will create the edges of the faces along the CV points on the curve. Click Revolve, and there it is (Figure 4-91).

Figure 4-90: Switch to the Surfaces menu set.

Figure 4-91: The wheel revolved

Figure 4-92: Adding detail to the wheel

Figure 4-93: Extrude out studs for the wheel.

Figure 4-94: The wheels and brackets are positioned, and the hierarchy is organized.

The file catapult_v3.mb in the Catapult project from the companion website reflects the finished wheels and base.

The Winch Assembly

To be able to pull the catapult arm down to cock it to fire a projectile, you’ll need the winch assembly to wind a rope that connects to the arm to wind it down into firing position. Since animating a rope can be a rather involved and advanced technique, the catapult will not actually be built with a rope. To build the winch assembly, follow these steps:

Figure 4-95: Create a profile curve and revolve it to create the object seen below the profile curve.

Figure 4-96: Place the pulley.

3. Now you’ll need some sort of geared wheel and handle to crank the pulley. Create a poly cylinder, and rotate it so it’s on its side like one of the wheels. Scale it to a squat disk with scale values of 1.4 in the X- and Z-axes and 0.4 in the Y-axis. Select the disk and bevel it.

4. Off on the side of your scene, create another poly cylinder, and rotate it to its side as well. Scale it to be a long, thin stick. You’ll use this as the first of eight gear teeth for the wheel. Position it at the top of the wheel as shown in Figure 4-97. Click the Snap To Points icon in the Status line (), and snap the pivot point (press D to move the pivot) to the center of the wheel. Turn off Snap To Points.

Figure 4-97: Making a gear wheel

5. Instead of duplicating the gear tooth and positioning it seven more times, you’ll use the array capabilities of the Duplicate Special tool. Select the tooth, and choose Edit ⇒ Duplicate Special . In the option box, set Rotate to 45 in the X-axis, and set Number Of Copies to 7. Since the pivot for the tooth is at the center of the wheel, as soon as you click the Duplicate Special button, Maya places seven copies around the wheel at 45-degree intervals (Figure 4-98).

Figure 4-98: Eight gear teeth in place

Figure 4-99: Use two cylinders and a poly cube to create the handle shapes.

Figure 4-100: Place the turn wheels.

Figure 4-101: The winch gears and handles

Figure 4-102: The assembled winch

To verify your work up to this point, compare it to catapult_v4.mb in the Catapult project from the companion website.

The Arm

OK, now I’m kicking you out of the nest to fly on your own! Try creating the arm (see Figure 4-103), without step-by-step instruction, using all the techniques you’ve learned and the following hints and diagrams:

Figure 4-103: The catapult arm assembly

• Create the intricate-looking arm with face extrusions. That’s all you’ll need for the arm geometry. Follow Figure 4-104 for subdivision positions to make the extrusions work correctly.

Figure 4-104: Follow the subdivisions on your model.

• Duplicate and place screw heads around the basket assembly, as shown in Figure 4-105.

Figure 4-105: Place screw heads around the basket arms.

• Create the straps for the basket with poly cubes. It’s easier than it looks. You’ll just need to create and extrude the cubes with enough subdivisions to allow you to bend them to weave them together, as shown in Figure 4-106. The ends of the straps wrap around the arm’s basket with extrusions.

Figure 4-106: Basket straps

• Create the hinge for the arm with a couple of duplicated brackets and a cylinder.
• Create the arm’s stand with multiple extrusions from a cube. Follow the subdivisions in Figure 4-107 for reference.

Figure 4-107: Follow the subdivisions on the arm stand.

• Bevel the parts you feel could use some nice edging, including the arm and stand pieces.
• Group the objects together and add their groups to the Catapult node.

When you’ve finished, save your scene file and compare it to catapult_v5.mb in the Catapult project from the companion website. Figure 4-108 shows the finished catapult.

Figure 4-108: The completed catapult

Suggestions for Modeling Polygons

Poly modeling lends itself nicely to a wide range of objects—practically anything you can think of and some things you can’t. Try modeling the following objects to fine-tune your skills and explore the tool set:

Summary

In this chapter, you learned about the basic modeling workflows with Maya and Modeling Toolkit and how best to approach a model. This chapter dealt with polygon modeling and covered several polygon creation and editing tools, as well as several polygon subdivision tools. You put those tools to good use by building a hand and smoothing it out, as well as making a model of an old-fashioned catapult using traditional Maya workflows as well as new Modeling Toolkit workflows. The latter exercise stressed the importance of putting a model together step-by-step and understanding how elements join together to form a whole in a proper hierarchy. You’ll have a chance to make another model of that kind in Chapter 6, when you create a child’s table lamp that is used to light and render later in the book.

Complex models become much easier to create when you recognize how to deconstruct them into their base components. You can divide even simple objects into more easily managed segments from which you can create a model.

The art of modeling with polygons is like anything else in Maya: your technique and workflow will improve with practice and time. It’s less important to know all the tricks of the trade than it is to know how to approach a model and fit it into a wireframe mesh.