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.)
When you dissect the components of an object into primitive shapes, you can then translate and re-create the object in 3D terms.
First, you should 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.
You must also decide the purpose for your model and 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 for 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 (the images on the 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.)
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 smooth lines, or curves, are the basis of all NURBS surfaces. 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, a process not covered by this book. Subdivision surfaces combine the best of both worlds but are not a popular workflow and is largely hidden in the interface now; therefore, it will not be covered in this book. Basic NURBS modeling is covered in the next chapter.
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.
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.
Primitives are the simplest objects you can generate in Maya (or in any 3D application). They are simple geometric shapes—polygons or NURBS. Typically, primitives are used to sculpt models because you can define the level of detail of the primitive’s surface; they offer great sculpting versatility through vertex manipulation.
To get a better sense of how to begin a modeling assignment, you may find it helpful to analyze your modeling subjects into forms and shapes that fit in with Maya primitives. 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 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 you typically need to create curves to start NURBS, you usually create complex polygons 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.
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 () in the status bar
along the top of the UI), 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 you’ll find the Subdivisions
Axis and Subdivisions Height sliders (in the option box, these are called Axis and
Height Divisions), which you can use to change the surface detail retroactively.
You use the Polygon tool to create a single polygon face by laying down its vertices (switch to the Polygons menu set and then choose Mesh Tools ⇒ EDIT ⇒ Create Polygon Tool, in the EDIT section of the menu). 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.
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 4-4: Polygon faces created with the Polygon tool
With the surface selected, choose Mesh ⇒ SHAPE ⇒ 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 4-5: A single-faced polygon with a complex shape
Figure 4-6: Complex shapes are better with more faces.
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 toy airplane 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, which are separated into sections according to function type. For example, tools that work on vertices are found under the Edit Mesh menu’s VERTEX section. It’s important to note these sections, as some tools have the same name and may be repeated more than once in the menu, but function differently if applied to vertices, faces, or edges.
Modeling Toolkit integrates component-level selection and editing tools (such as selecting vertices, edges, and faces, and extruding them, for example) 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 2015 alongside Maya traditional workflows to give you a comparison and allow you to decide which workflow suits you. You’ll take a look at Modeling Toolkit and its interface later in the chapter.
The most commonly used poly editing tools have to do with extrusion. You can use Extrude to pull out a face, edge, or vertex of a polygon surface to create additions to that surface. You access the tool in the Edit Mesh menu under the respective section (FACE, EDGE, or VERTEX) ⇒ Extrude. Maya distinguishes between edge, face, or vertex extrusion based on which of those components you’ve selected and under which menu section you select the Extrude command. 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, Shift+select the
faces, 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
Although it seems to be strange behavior, the Twist and Taper values are taken into account in the extrusion. You can edit these values when you uncheck Selected, 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 makes selecting and editing polygonal components more streamlined, accelerating some workflows by incorporating tools into one place for ease of access as well as by reducing how often 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.
Figure 4-9: Loading the Modeling Toolkit plug-in, if needed
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 (or ModelingToolkit.bundle on a Mac). Check Loaded and Auto Load, as shown in Figure 4-9.
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 component selection mode. 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 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.
Now that you have a little background on how Modeling Toolkit integrates with Maya 2015, let’s use it in comparison to the Maya Extrude tool you just used on a sphere.
Figure 4-11: The Modeling Toolkit panel
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
All of these extrusion options and settings are available in the Maya Extrude tool but are a little more streamlined 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.
Figure 4-15: Keep Faces Together is turned off.
Similar to extruding faces, Wedge 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 power icon () to turn off the blue
light.
Figure 4-16: Executing a Wedge operation on a face of a sphere
RMB+click a mesh and select Multi from the marking menu. Select a face, Shift+select
one of the face’s edges, and choose Edit Mesh ⇒ FACE ⇒ Wedge
(under the FACE section of the menu).
In the option box, notice 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.
As a reminder, you can RMB+click an object to display a marking menu. Drag the cursor to select Multi and release the mouse button to be able to select a face and then an edge for the Wedge operation. Then, click or Shift+click your selection.
The Wedge tool is useful for items such as elbows, knees, archways, and tunnel curves.
Figure 4-17: Poke helps create areas of detail in your model.
Poke is great for creating detailed sections of a mesh (poly surface) and bumps or indentations. To use the Poke tool to add detail to a face, select a face and then choose Edit Mesh ⇒ FACE ⇒ Poke.
A vertex is added to the middle of the face, and the Move manipulator appears on the screen for that new vertex, 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.
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 ⇒ EDGE ⇒ Bevel
(under the EDGE section of the menu)
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).
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.
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.
Figure 4-18: Increase Segments to create a rounder corner.
Figure 4-19: A poly bevel’s roundness set too high
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:
Figure 4-20: Modeling Toolkit also has easy planar movement handles to components with its three circles in the manipulator.
As you can see, using Modeling Toolkit makes the Bevel tool slightly easier and faster to implement. 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.
Figure 4-21: The Modeling Toolkit bevel is the same as the Maya bevel shown in Figure 4-18.
Starting with a simple polygonal cube, you’ll create a basic cartoon hand using a mix of Maya and Modeling Toolkit workflows.
Download the entire Poly_Hand project from the web page (www.sybex.com/go/introducingmaya2015) where you can also find a video for this tutorial. Set your project to this folder and follow these steps:
Figure 4-22: The poly cube in position to make the hand
Figure 4-23: Rotate the face (left) and then extrude the index finger.
Save your work, and compare it to the scene file
poly_hand_v1.mb
in the Poly_Hand project on the web
page.
Figure 4-24: Three fingers
Use Table 4-1 as a guide for the extrusion lengths (Local Z value) for each finger.
Table 4-1: Extrusion length guide
Finger | Extrude Local Z value |
Middle | 4.2 |
Pinkie | 3.0 |
When you’re finished with the three fingers, select the hand; in the Perspective panel, press 2 to give you a smooth preview of the hand. With a polygonal object, pressing the 1, 2, and 3 keys previews the smoothness your model will likely have when it’s smoothed (a polygonal modeling operation about to be discussed). Pressing 2 also shows the original shape of the hand as a wireframe cage (see Figure 4-25, left).
Figure 4-25: A smoothed preview of the hand, with the original shape shown as a cage (left) and a full smooth preview without the cage (right)
With the hand still selected, press 3. The original wireframe
cage disappears, as shown in Figure 4-25 (right). This
doesn’t alter your model in any way; if you render, your hand will still be blocky, just as you
modeled it. Press 1 to exit the smooth preview and return to the original model
view. The scene file poly_hand_v2.mb
shows the hand with the three
fingers created.
Figure 4-26: Insert an edge loop at the base of the hand.
Figure 4-27: Insert a second loop of edges up toward the middle of the hand.
Figure 4-28: Scale and rotate the thumb’s face to get it ready to extrude.
Figure 4-29: Extrude the thumb.
Figure 4-30: Create a flare at the base of the hand.
Figure 4-31: Select all the edges outlining the entire hand.
Figure 4-32: Beveling all around the hand (left) and shown with Smooth Preview (right)
Figure 4-33: Scale down these faces to flare the thumb a bit more.
Figure 4-34: Use the Multi-Cut tool to lay down edges for the knuckles.
Figure 4-35: Use the Poke tool to raise the knuckles.
To verify that you’ve been working correctly, you can load the finished hand file
(with its history intact), which is called poly_hand_v3.mb
, available
from the book’s web page, www.sybex.com/go/introducingmaya2015. If you don’t need any of the history
anymore, then with the hand selected, choose Edit ⇒ Delete By Type ⇒ History to get rid of all those extra
nodes.
Figure 4-36: Set the options for the Smooth operation (left), and the smoothed hand is shown with all its history nodes (right).
As you saw with the cartoon hand, it became necessary to add more faces to parts of the surface to create various details, such as with the knuckles. Maya provides several ways to add surface detail or increase a poly’s subdivisions, as you’ve begun to see in the cartoon hand exercise. Let’s take a deeper look at these and more tools for adding detail to a mesh.
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 ⇒ FACE ⇒ Add Divisions (under the FACE section
of the menu). Make sure not to select the first Add Divisions entry, which is under
the EDGE section of the menu; otherwise, you will split the edges surrounding the
selected face instead of splitting the face into more faces. In the option box, you
can adjust the number of times the faces are divided by moving the Division Levels
slider. With Add Divisions set to Exponentially
under the Settings
heading, 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.
Figure 4-38: Dividing edges
You can also select a poly edge to divide. Running this tool on edges divides the selected edges into separate edges along the same face, giving you more vertices along that edge. It doesn’t divide the face; rather, you can use it to change the shape of the face by moving the new vertices or edge segments, as shown in Figure 4-38. Just make sure to select Add Divisions under the EDGE section of the Edit Mesh menu.
You use the Add Divisions tool to create regions of detail on a poly surface. This is a broader approach than using the Poke tool, which adds detail for more pinpoint areas.
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. You access the Multi-Cut tool when Modeling Toolkit is enabled, 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
You can also access the Multi-Cut tool through Mesh Tools ⇒ EDIT ⇒ Multi-Cut Tool (under the EDIT section of the menu).
Figure 4-40: Using the Insert Edge Loop tool
This handy tool adds edges to a poly selection, much like the Multi-Cut 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 Modeling Toolkit Multi-Cut tool. You used this tool in the decorative box in Chapter 3 and earlier in this chapter on the cartoon hand 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 Multi-Cut tool. With a poly cube selected, choose Mesh Tools ⇒ EDIT ⇒ 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 4-40. If you click and drag along an edge, you can interactively position the new split edges.
Much like the Insert Edge Loop tool, the Offset Edge Loop tool (Mesh Tools ⇒ EDIT ⇒ Offset Edge Loop Tool) inserts not one but two edge loop rings of edges across the surface of a poly. Edges are placed on both sides of a selected edge, equally spaced apart. For example, create a polygon sphere and select one of the vertical edges, as shown in Figure 4-41. Maya displays two dashed lines on both sides of the selected edge. Drag the mouse to place the offset edge loops; release the mouse button to create the two new edge loops.
Figure 4-41: The Offset Edge Loop tool and its options
The Offset Edge Loop tool is perfect for adding detail symmetrically on a surface quickly.
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 4-42). You can also select Mesh Tools ⇒ EDIT ⇒ Connect Tool in the main menu bar.
Figure 4-42: The Modeling Toolkit Connect tool creates edges much like Insert Edge Loop.
One of Modeling Toolkit’s nicest features is its drag selection mode. This allows you to essentially click and drag your cursor over the components you want selected with your cursor instead of having to click every component, almost like painting.
Figure 4-43: Create a subdivided box.
Figure 4-44: Drag+select a six-face square on the front of the box.
Figure 4-45: Delete the square shapes out of the box.
Figure 4-46: Select these edges (left) and bridge them (right).
Experiment with the Divisions attribute for the Modeling Toolkit Bridge to get a curvature in the bridged faces.
Figure 4-47: Bridge the bottom faces.
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, making modeling appreciably faster. While Maya has its own Symmetry 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 Maya’s symmetry mode. Let’s see how Modeling Toolkit Symmetry works.
Figure 4-48: Turn on Symmetry mode.
Now if you engage any poly editing function, it will act on the symmetrically selected components.
Figure 4-49: Selecting faces on one side selects them on the other.
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.
Frequently, when you’re modeling a mesh, you’ll need to fold over pieces and weld parts together, especially when you combine meshes into a single mesh. 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. The Merge Components tool fuses multiple vertices at the same point into one vertex on the model. And the Merge Vertex tool from Modeling Toolkit is a more interactive way to fuse vertices together. We’ll take a look at both in order to compare the workflows.
In the following simple example, you’ll create two boxes that connect to each other along a common edge, and then you’ll combine and merge them into one seamless polygonal mesh. To begin, follow these steps:
Figure 4-50: Place two polygonal cubes close to each other.
Figure 4-51: Extrude the bottom edge to create a flange.
Figure 4-52: Snap the first corner vertex to the newly extruded face (left), and then the second (right).
Even though the cubes seem to be connected at a common edge, they’re still two separate polygonal meshes. You can easily select and move just one of the stacked vertices and disconnect the connective face of the two cubes. You need to merge the stacked vertices of the cubes into a single vertex. However, the Merge Components function won’t fuse vertices from two separate meshes together; you must first combine the cubes into a single poly mesh. The following steps continue this task.
Figure 4-53: There are still two different vertices at the corner, and the boxes aren’t really connected (left). The back corner is now connected properly (right).
Figure 4-54: Merge Vertex tool in action.
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 Components and the Merge Vertex tool cut down on unwanted vertices.
If you need to move an edge on a model, selecting the edge or edges and using the Move tool will change the shape of the mesh. Let’s see how this works:
Figure 4-55: Create a cone (left). The middle image shows what happens to the cone when you move the middle loop of edges as opposed to using the Slide Edge tool as shown on the right.
The Slide Edge tool is perfect for moving edges on a complex mesh surface without altering the shape of that surface.
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 4-56). Select the poly object, and choose Mesh Tools ⇒ EDIT ⇒ Cut Faces Tool. Click the option box if you want to extract or delete the section.
Figure 4-56: 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.
Select one or more faces and choose Edit Mesh ⇒ FACE ⇒ Duplicate to create a copy of the selected faces. You can use the manipulator that appears to move, scale, or rotate your copied faces.
Figure 4-57: Pull off the faces.
The Extract tool is similar to the Extrude tool, but it doesn’t create any extra faces. Select the faces and choose Mesh ⇒ SEPARATE ⇒ Extract to pull the faces off the surface (see Figure 4-57). 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.
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 faces. When you use this tool with the Multi-Cut tool to make custom edges, you can create cutouts of almost any shape. You’ll see this functionality of creating custom shaped holes with the Split Mesh with Projected Curve function explored below as well.
The Smooth tool (choose Mesh ⇒ SHAPE ⇒ Smooth) evenly subdivides the poly surface or selected faces, creating several more faces to smooth and round out the original poly object, as you saw earlier in this chapter with the cartoon hand model exercise.
Sometimes you need to cut a hole in a mesh. You can simply select faces on that mesh and delete them to create a hole. However, if you need a more intricate, custom-shaped hole, you’ll need to first use Split Mesh with Projected Curve to make a custom shape.
Make the selected object
live
icon in the status bar next to the snapping icons (No Live Surface
to
pSphere1
and will turn blue (curve1
. More on creating curves can be found in Chapter 5.Figure 4-58: Draw an EP curve directly on the sphere (left). The projected curve (seen on the sphere in pink) adjusts if you move the original curve (seen away from the sphere in green).
curve1
in the Outliner (Figure
4-58, right) and move it around in your scene, the projected curve on
the sphere (seen in your scene as pink) will adjust, staying on the sphere as
shown in Figure 4-58 (right).polyProjectionCurve1
) and choose Edit Mesh ⇒ CURVE ⇒ Split Mesh with Projected
Curve.pSphere1
and curve1
), as
well as the projected curve (polyProjectionCurve1
), leaving you
with pSphere2
. Figure 4-59: Splitting the sphere with its projected curve (left), and then deleted those faces to make a custom hole (right).
Projecting a line shape onto a mesh surface will allow you to not only cut holes as in this exercise, but it’s also very handy for easily creating custom lengths of edges for modeling use.
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, as
you will see with the candle modeling exercise in Chapter 5, “Modeling with NURBS
Surfaces and Deformers.” In that chapter you will use this tool to add detail to a
polygon model. Once you have played with the Sculpt Geometry tool in Chapter 5, try
loading the poly_hand_v3.mb
model and sculpting some detail into the
cartoon hand.
To access the tool in polygon modeling, select your poly object and choose Mesh Tools ⇒ EDIT ⇒ Sculpt Geometry Tool
.
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 4-60).
Figure 4-60: The Sculpt Geometry tool deforms the surface.
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/introducingmaya2015) 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, let’s use 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 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:
You will model each part separately based on the sketch in Figure 4-61 and the detailed schematic in Figure 4-62.
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.
Figure 4-61: A sketch of the catapult to model
Figure 4-62: A schematic diagram of the finished model to illustrate the goal
To begin the catapult base, follow these steps:
Figure 4-63: Create a bevel for the baseboard object.
Figure 4-64: Beveling the bottom edges
Figure 4-65: The long boards at the base (top) and the platform board is in place (bottom).
Figure 4-66: Cross bracing the base
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 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.
Now you have both objects that you need for a Boolean operation, and they are placed properly to create a slot in the top of the screw head.
Figure 4-70: Selecting a Difference Boolean
Figure 4-71: The screw head is slotted.
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.
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, earlier) 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: Use Modeling Toolkit Extrude to extrude the face.
Figure 4-76: 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).
Figure 4-78: Delete the face (left) and set the Mirror Geometry options (right).
Figure 4-79: The winch’s base completed
Figure 4-80: MMB+dragging the duplicated bracketGroup to another location in the Outliner removes the group from the Winch_baseboard1 group.
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 4-81: 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.
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.
Figure 4-88: The profile curve for the wheel
Figure 4-89: The profile curve is in place for the rear wheel.
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.
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.
Figure 4-97: Making a gear wheel
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
To verify your work up to this point, compare it to catapult_v4.mb
in
the Catapult project from the companion website.
Figure 4-102: The assembled winch
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
Figure 4-104: Follow the subdivisions on your model.
Figure 4-105: Place screw heads around the basket arms.
Figure 4-106: Basket straps
Figure 4-107: Follow the subdivisions on the arm stand.
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
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 cartoon 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 toy airplane 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.