Maya Rendering Guides

The Boiler Engine

The most prominent part of a steam locomotive is the steam engine, or boiler. Take a look at its shape. You can start with a simple cylinder and work from there. To start building the boiler engine, follow these steps: 1. Create a polygonal cylinder by choosing Create * Polygon Primitives * Cylinder. Leave all the creation option settings at their defaults (do not enable Interactive Creation) to create the cylinder.

1. Rotate the cylinder 90 degrees in the X-axis to place it on its side. Scale the cylinder to about 1.8 in all axes. Then lengthen the cylinder until Scale Y is at about 8.9. You can either use the Scale manipulator or enter the values in either the Channel or Input boxes.
2. We will use the Insert Edge Loop tool mentioned earlier in this chapter to insert edges into the cylinder to make one end smaller. Select the cylinder, and choose Edit Mesh ■ Insert Edge Loop Tool □. In the option box, make sure Maintain Position is set to Relative Distance From Edge and Auto Complete is turned on. Your cursor will turn into a triangle pointer. In two separate actions, click one of the horizontal subdivisions to create two new vertical edges about one-third of the way in from the right end of the cylinder, as shown in Figure 4.26.
3. Right-click the cylinder and choose Face from the marking menu. Select the end faces and scale them down a bit as in Figure 4.27. This gives us the main part of the boiler engine.

Figure 4.26

The Edge Split tool creates subdivisions quickly.

Figure 4.26

The Edge Split tool creates subdivisions quickly.

Figure 4.27 Scale the end faces.

5. Make a new poly cylinder as before. Scale the cylinder to make it a flat plate and place it on the boiler. The cylinders will need to be scaled to fit snugly over the boiler as you see fit. This will give us a simple weld plate to provide the boiler with some simple detail. Choose Edit ■ Duplicate Special □ to copy the plate four times in one action. In the option box, set Number Of Copies to 4. Now move these duplicates one by one back along the boiler cylinder and place them through the skinny section of the boiler. Arrange a total of five plates along the boiler, as shown in Figure 4.28.

Boiler Front Cap

Now we will create the boiler's front cap. Here we will use a NURBS curve to create a NURBS surface using a technique called Revolve, which we will discuss in more detail in the next chapter.

First, switch to the Surfaces menu and then follow these steps: 1. Choose Create * CV Curve Tool, and in the Side View panel, lay down CVs as shown in Figure 4.29 from the top of the curve down. Make sure you begin the curve about 1.5 units from the Z-axis so you can end the curve on the Z-axis line, as shown in Figure 4.29. When you have placed your last CV, press Enter to complete the curve. Don't worry if it is not exactly like the curve shown. When you finish the curve in step 1, you should notice that Maya no longer displays its CVs in the panel. To display the CVs on a NURBS object,

Figure 4.29 Draw a curve to create an outline for the boiler front cover.

such as this curve, select the object and choose Display * NURBS * CVs. You can toggle the CVs off by choosing the same menu items again.

2. This curve is called the profile curve, and it will spin around to sweep a surface for the boiler cap. We need to revolve the curve around its bottom end to sweep a proper surface. Because you created the curve to end on the Z-axis, and the pivot point for the curve is by default at the origin, simply select the curve and choose Surfaces * Revolve □. Set Axis Preset to Z. Click Revolve to create the boiler cap.

Now that you have created the boiler cap, select the curve and move it in the scene. You will notice that the surface changes. This is how the history is displayed on the resulting surface. As we touched on in Chapter 3, Maya's History functionality keeps a record of how the object was made, as long as the Construction History icon in the Status Line is on.

3. We don't want history on the object, so select the boiler cap and choose Edit * Delete by Type * History. This will erase the history so the curve no longer affects the surface. Move the boiler cap into place at the front of the boiler. Scale it as needed to fit the cylinder's skinny end. (See Figure 4.30.)

Figure 4.30 Fit the boiler cap onto the boiler engine.

ti porep

Adding Details

Now we will include a bit of detail by adding bolts to the front boiler cap and the weld plates. This will introduce you to the process of copying multiple objects into position automatically, otherwise know as copying into an array. To create the bolts, follow these steps:

1. Create a poly sphere by choosing Create * Polygon Primitives * Sphere □. In the option box, set both Axis Divisions and Height Divisions to 6. Click Create. This makes a crude sphere at the origin, perfect for a bolt. Scale the sphere down to 0.07 in all axes to make it the right size.
2. We need to duplicate this bolt many times to place it around the boiler cap and the weld plates. Instead of moving them into position one by one, we will create a circular array of bolts that we can group together and slap on the boiler. Move the bolt to the boiler cap, and place it on the left side of the boiler cap, halfway into the surface, as in Figure 4.31.

Figure 4.31 Place the bolt on the left side.

1. Enter Pivot Placement mode by pressing Insert (Home on a Mac) to move the pivot of the bolt to the center of the boiler cap, and then exit Pivot Placement mode by pressing Insert (or Home) again.
2. We will copy 19 more bolts to go around the boiler cap at 18-degree intervals, pivoting around the center of the boiler cap. Select the bolt and choose Edit * Duplicate

Special □. In the option box, set Number Of Copies to 19, and set a value of 18 for Rotate Z, as shown in Figure 4.32. Click Apply to copy the bolts all the way around the boiler cap. The copies arrayed themselves around their common pivot point (i.e., the center of the boiler plate) at 18-degree intervals.

If you make the copies without moving the pivot point of the original bolt to the center of the boiler cap, none of the 19 copies will be arrayed into the nice circle around the boiler. They will end up in different configurations.

Figure 4.32 Multiple copies of the bolt are placed automatically.

1. Notice that the option box does not close when you click Apply. Make sure to reset Duplicate Options back to normal.The next time you try to duplicate an object, you will get 19 instances of it if you don't! In the option box, choose Edit ■ Reset Settings,
2. In the Outliner, select the 20 bolts and choose Edit ■ Group (or press the hot key combination Ctrl+G) to group them. Call the new group boiler_bolts or something similar to keep organized. Center the pivot on the new group by choosing Modify ■ Center Pivot.
3. Select the boiler_bolts group, and duplicate it once to create another set of bolts you can place on the welding plates. You will have to scale the duplicated boiler_bolts group up a bit to make all the bolts fit around the weld plates. Repeat for the other plates as shown in Figure 4.33. Make sure you reset the duplicate options when you are finished to keep from making 19 copies next time around.

Figure 4.33 Duplicate the boiler bolts for all the plates

To check your work or if you've just skipped ahead to this point, you can load the scene file locomotive_v1.mb from the Locomotive project on the CD.

The Undercarriage

Now we can tackle the base on which the boiler sits. Take a look at Figure 4.34, which shows a schematic view of the boiler sitting on the undercarriage of the train. Luckily, we have the luxury of referring to the final model here to better visualize what we're modeling.

Follow these steps to continue with the engine.

1. Create a poly cube and scale it to X = 2.7, Y = 2.95, and Z = 17.55. This will form the main length of the undercarriage you saw in the sketch in Figure 4.25, earlier in the chapter. Now we will use extrusions to create the ends. To make viewing easier while you create the undercarriage, you could select all the boiler elements and place them on a display layer to hide them as you work on this section, or simply move the cube away from the boiler for the time being and move it back when you're finished.

Figure 4.35 Extrude the face and scale it down

2. Switch back to the Polygons menu, and right-click the cube you just created. Choose Face from the marking menu, and select the left end of the face. Choose Edit Mesh * Extrude. Using the Transform manipulator on the special Extrude manipulator, pull out the face slightly. Use the Scale Y manipulator (the green box) to scale the new face smaller in the Y-axis and move it up as shown in Figure 4.35.

Figure 4.35 Extrude the face and scale it down

1. With the new face still selected, choose the Extrude tool again, and pull a new face out about 2.5 units to create a lip as shown in the second image in Figure 4.24b.
2. At the other end, we need to make a thinner lip. Select the poly object and choose Edit Mesh * Insert Edge Loop Tool. Place a horizontal edge about one-fifth of the way down from the top edge. Choose the Extrude tool (from the Edit Mesh menu or from the Polygons tab of the Shelf, using the icon) and pull the newly divided face out 3.5 units (Figure 4.36). This completes the main undercarriage piece.
3. Create three polygon cubes, and scale and position them at the right end of the undercarriage as shown in Figure 4.37. For now, just fit them in without worrying about overlapping or interpenetrating geometry.

Figure 4.36 Figure 4.37

Extrude to complete the undercarriage piece Place three cubes into the undercarriage

Figure 4.36 Figure 4.37

Extrude to complete the undercarriage piece Place three cubes into the undercarriage

If you would like to make your models look like the preceding image, with the wireframe lines showing in shaded mode, enable Shading ■ Wireframe On Shaded in the panel view. This will help delineate the model.

6. For a finishing touch back there, we will round out the lip we created in step 4. Select the face on the end of the lip, and then right-click it again. This time choose Edge from the marking menu, and Shift+select the bottom edge as shown in Figure 4.38. Choose Edit Mesh ■ Wedge Face □. Set Arc Angle to 90 and Divisions to 6. Click Wedge Face, and you will see a result similar to that shown in Figure 4.39. These little impromptu details help make your model nicer.

Figure 4.38 Figure 4.39

Select the end face for a Wedge operation The rounded back lip of the undercarriage

Figure 4.38 Figure 4.39

Select the end face for a Wedge operation The rounded back lip of the undercarriage

7. The next piece of the undercarriage fits on the left hand or front end and eventually attaches to the cowcatcher of the locomotive. Create a polygon cube, and scale it to X = 4.45, Y = 0.16, and Z = 4.0. Using the Insert Edge Loop tool, place nine equidistant subdivisions on the polygon slab, as shown in Figure 4.40. Notice that if you click and hold with the Insert Edge Loop tool, you can drag the location of the new edge line. This way you can more easily position the lines.

Figure 4.40 Place nine subdivisions on the poly slab.

Figure 4.41 Create an arc by moving the bottom faces down individually.

8. Select the bottom faces and move them down individually to create an arc, as shown in Figure 4.41. There is no need to extrude the faces; moving them one by one is fine. Place the new piece at the front of the undercarriage, as shown in Figure 4.42.

Figure 4.41 Create an arc by moving the bottom faces down individually.

1. Let's tackle the cowcatcher. Create a polygon cube with eight subdivisions along its width. Scale the cube to 4.4 in X, 2.15 in Y, and 1 in Z. We will use this subdivided cube to pull vertices to make a cowcatcher shape. Enter Component Selection mode, pick the front top vertices, and move them down to make a wedge, as shown in Figure 4.43.
2. Select all the front vertices and the middle five back vertices along the bottom. Scale them in together in the Z-axis and then in the X-axis. Move them all forward to create the cowcatcher, as shown in Figure 4.44. Place the cowcatcher at the front of the undercarriage, as shown in Figure 4.45.

Figure 4.42 Figure 4.43

Attach the new piece beneath the front of the train. Begin the cowcatcher with a simple wedge

Figure 4.42 Figure 4.43

Attach the new piece beneath the front of the train. Begin the cowcatcher with a simple wedge

11. Place three poly cube slabs approximately as shown in Figure 4.46 for the boiler platforms. Group all these undercarriage pieces together and name them in a way that will help you stay organized. Also, make sure to group the parts of the boiler in a logical manner. The Outliner is shown in Figure 4.47 with the organization of the model so far.

You can load the scene file locomotive_v2.mb from the Locomotive project on the CD to check your work.

Figure 4.46

The boiler platforms are simple cubes.

SS Outliner - filET
ueptay Show 1
t;
Is O		ion	«
		botto_c>4nder
	9	bofa.cto
□	0	wckLptotaî
F1	a	befa.buts
		pifihrtr-l
		DSpbwrf
		pSphrtrJ
		P$f*«a5
		pSpbnefi
		pSpKMft7
		pSphne6
		pfiptvxrfl
		pSphnelO
		pSptvsnll
		pSphael?
		(/SphwM
		pSphmftlB
		pSpfnelC
		piphrtr-17
		pSpheielS
		pSfihrtr-lfl
	ft-	pSpfine20
□	a	bidm.hnbl
F1	a	Iwfe Iwfci2
□	a
R	0	Infa bufc*4
□	a
B	a	in iJpii.aiii.j'jT!
	«>	hn iwiirlJndmnnMgii; U)_gr«n
		lui insnUrnJettaiiuje 02 gam
		lm_flviinlJndrf(,jwiMgiî_fl3
		Ijii n-jtUr rjn s< 11-» js 04 gewii
		hnjMirl J rvWf\vn.*jr_f
1=1	0	Ms pUW
		lm_hnlrtFWinima_01_giMm
		In» bofciPhlfaint. 02 gmn
	<8>	lm_hninPtiVfnmM_rLl_9nfim	The Outliner view of the locomotive geometry Figure 4.46 The boiler platforms are simple cubes. Figure 4.47 The Outliner view of the locomotive geometry Finishing the Boiler The fun parts of a steam locomotive are all the chimneys on top of the boiler. To create the main steam chimney and give it a revolving surface, follow these steps: You will need to draw a profile curve for the smokestack/chimney. Choose Create * CV Curve Tool □. In the option box, set Curve Degree to 1 Linear. This will allow you to create straight curves. In the Top View panel, start from the bottom and lay down CVs similar to those shown in Figure 4.48. Press Enter when you finish. Make sure to reset the options to the defaults when you're done. This profile curve should now be about five units tall in the Z-axis in the Top View panel and have its pivot point at the origin. Enter the Surfaces menu, select the curve, and choose Surfaces * Revolve □. Figure 4.48 The profile curve for the chimney Figure 4.49 The engine's chimney Change Axis Preset to Z. Also, at the bottom of the window, change Output Geometry to Polygons. We will not create a NURBS surface as we did before with the boiler cap, but instead will go for a poly revolve. Change Type from Triangles to Quads. This will create polygon faces that are rectangular rather than triangular. Under Tessellation Method, select Standard Fit. Click Revolve and you should have a chimney similar to the one shown in Figure 4.49. You may need to orient the chimney to fit the boiler properly if it is lying flat. 3. Delete the history by selecting the chimney and choosing Edit ■ Delete By Type ■ History. Place the chimney as shown in Figure 4.31. You can move the vertices at the bottom of the chimney to fit it to the round engine boiler as shown in Figure 4.50. You can also set to the Polygons menu. Figure 4.49 The engine's chimney Here is where I kick you out into the cruel hard world and make you create the remaining pieces for the engine boiler before we move on to the steam pumps, main cabin, wheels, and drive axles. You will find suggestions on how to create the individual pieces in this section. (We will set up the wheels in the animation chapters that follow.) Study the following figures and graphics to get an idea of how to create these pieces using the Revolve Surface tool and the other polygon toolsets used in this exercise and in this chapter. Figure 4.51 shows the extra pieces for you to build. Figure 4.51 You're on your own! Figure 4.52 Create the lightbox object from a simple cube You can build the light box shown in Figure 4.52 from a polygon cube by adding subdivision edges with the Insert Edge Loop tool and extruding or moving faces in and out. The light itself is a simple cylinder set into this shape. Figure 4.52 Create the lightbox object from a simple cube Figure 4.53 Use Revolve surface to create the Boiler Caps You can draw the two top boiler caps by drawing a profile curve and then revolving the boiler caps as we did for the chimney (Figure 4.53). Figure 4.53 Use Revolve surface to create the Boiler Caps The piping and small tanks along the length of the engine boiler are simple cylinders placed in position, as shown in Figure 4.54. Figure 4.54 Place the piping on the boiler The side panel details are simple poly cubes that have some faces extruded, with a few faces cut out (Figure 4.55). Figure 4.55 The side panels You can load the scene file locomotive_v3.mb from the Locomotive project on the CD to go over the models firsthand and get a much closer look. You can use the scene file to help build the pieces shown in this section to complete the engine boiler and its details. The following sections will cover the cabin and wheels.

+1 0

Average user rating: 5 stars out of 1 votes