Modeling a Jetpack Game Asset – Part 2: Fuel tanks, stabilizers and thrusters
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Modeling a Jetpack Game Asset – Part 2: Fuel tanks, stabilizers and thrusters

August 8, 2019

In the previous movie, we started modeling our jetpack using box modeling techniques to keep the asset’s polygon count under control. In this movie, we’ll continue this process by tackling the jetpack’s fuel tanks, stabilizers, and thrusters. Open the file “Jetpack_game_asset_part2_start.mlt” or continue using your own file from the previous lesson. Before we begin, let’s add the jetpack shell object in a new layer. Rename it ‘shell_LYR’ and set its Display type to ‘Template’. This disables our ability to select it so it won’t get in the way when we model our jetpack components. To help highlight the fuel tanks, stabilizers, and thrusters’ outlines, we’ve included a new set of reference images with the scene files available for download with this movie. Now let’s start with the left fuel tank. It’s shaped like a tilted dome connected to the slanted jetpack shell. It also has a cavity to accommodate the stabilizers. First, open your preferences and make sure that in Settings, your angular working units are set to ‘degrees’. In the Create menu, turn off Interactive Creation. Create a cylinder polygon primitive and position it in all views based on the reference images. Rotate it -38 degrees in the Z axis to match the front reference image. In the Channel Box, under Inputs, click the polyCylinder1 shape node and set the Subdivision Axis and Height attributes to ’12’ and ‘5’, respectively. Open the Modeling Toolkit and activate it. We want to extrude the top section of the cylinder to create the tip of the fuel tank’s dome. We could select the faces individually, but instead let’s try a different method. Go to the Vertex selection mode and select the center vertex. CTRL+click Face selection to convert your selection to faces. Click Extrude, then set the Local Z option to 0.5 to specify the distance of the extrusion along the faces’ local Z axis, and set the Offset option to 0.5 to scale the faces inwards relative to the extrusion. Click Enter to confirm. Adjust the cylinder to match the fuel tank’s shape by scaling its remaining edge loops in the front and side views. You’ll notice that scaling in the X or Y axes shears the selection since Maya LT is currently set to World space. Under Transform Options, change the coordinate space to ‘Object’ so that Maya LT uses the cylinder’s local space instead, which aligns the manipulator accordingly. Let’s shift our focus to the lower portion of the fuel tank that connects to the jetpack’s stabilizers. Move the bottom edge loop down in the Y axis until it covers the stabilizer cavity in the front reference image. Since we don’t really need the bottom faces from our original cylinder, let’s remove them. You can quickly select the faces with the same selection conversion technique we used earlier. We’ll create the cavity using the Symmetry tool like in the previous movie. Select one of these edges to define the mirrored plane, and enable Symmetry. Rotate the cylinder by -11 units in the Y axis to better align it to the side reference image. Select these edges and click Connect. Use the default setting and press Enter to confirm. Convert this n-gon into a quad by connecting this edge to this vertex. Adjust the resulting vertices using the Edge Slide transform constraint to better match the cavity opening while maintaining the cylinder’s topology. In Face selection mode, select the four faces that make up the opening and extrude them. Pull the resulting faces outwards in the X axis to match the front reference image. Extrude the faces again. This time, set Offset to 0.15 to scale the extrusion inwards. Create one last extrusion. Set Offset to 0.1, and push the resulting faces back into the fuel tank. Delete the bottom faces of the last three extrusions. Then select the bottom edge loop and scale it in the Y axis to align them together. Select these vertical edges and press CTRL+Delete to delete them as well as their associated vertices. Create a new edge connection between this vertex and the center vertical edge. From here, you can disable the Symmetry tool and adjust the vertices to match the fuel tank outline. Since the fuel tank is wider than the jetpack shell, we can’t leave the giant hole at the bottom so we’ll use the Bridge tool to cap it. Select two opposing edges and click Bridge. Set Divisions to 1 and press Enter. Repeat this process to connect the other opposing edges. Remember that we always want to maintain quad-faced polygons as much as possible. As a final touch, select the bottom edges and click Bevel to create a more-detailed border rim. The Bevel tool might create triangles at certain points. To clean them up, click Target Weld and drag one vertex onto another to merge them together. Let’s now create the left stabilizer, which is essentially a sphere with an extruded cavity. Create a polygon sphere and position it in all views based on the reference images. Rotate it -17 units in the X axis, -5 units in the Y axis and 45 units in the Z axis, and scale it down to 0.85 units in all three axes. Click its polySphere1 shape node and set its Subdivision Axis and Height attributes to ’12’ and ‘8’, respectively. Let’s first tackle the opened section of the stabilizer revealing the propeller inside. In the perspective view, select the sphere’s edge loop furthest from the fuel tank. Convert that selection to faces. In Object coordinate space, align these faces in Y by scaling them together. Go back to Edge selection mode and scale the current edge loop to create the inside rim. Now extrude the flattened faces inwards to create the stabilizer cavity. Set Local Z to -0.3 and Offset to 0.05. The next two extrusions will create the propeller tip. The first one takes care of the base. Set the offset to 0.2. The second extrusion creates the actual tip. Set Divisions to 2, Local Z to 0.35 and Offset to 0.15. To sharpen the stabilizer’s rims, bevel these three edge loops like we’ve done before. Following the techniques you’ve learned so far, extrude the other side of the stabilizer so it extends into the fuel tank. The last object we’ll model is the main thruster. You can think of it as combination of the fuel tank’s slanted cylinder shape and of the stabilizer’s inward cavity. Create a polygon cylinder and position it in all views based on the reference images. Rotate it -15 units in the X axis to match the thruster. Scale it until the cylinder encompasses the reference images. Set its Subdivision Axis and Height attributes to ’12’ and ‘6’, respectively. Using the techniques learned while building the fuel tank, scale each loop in the X axis to match the outline contours in the front view. In the side view however, you’ll notice by the angle of the opening that the thruster was perhaps sliced off to reveal its inner propeller. So what we can do here is scale the edge loops in the Z axis to match the thruster’s outline as if it were a closed object, then slice off the part that we don’t need using the Multi-Cut tool. The Multi-Cut tool lets you create new edges three different ways: You can create arbitrary cuts in a polygon mesh to split faces. You can insert entire edge loops within your topology by first holding CTRL to preview your loop and then clicking to confirm. You can create slices by cutting faces perpendicular to the view plane, which is what we’ll do here. Click Multi-Cut, and in the side view click outside of the thruster mesh, near to the top of the opening. Click again near the bottom of the opening. A green dotted line connecting the start and end points of your slice previews the cut. You can drag the two slice points to adjust the cut if you want. When you’re ready, press Enter to confirm. With the thruster sliced in half, delete the unwanted faces. Before we create the thruster cavity and propeller, we should clean up the mesh’s topology by getting rid of these n-gons. First, use the Connect tool to create a new edge loop following the thruster’s topology. Use the Target Weld tool to condense the amount of vertices defining the rim and convert the n-gons into quads. From here, adjust the cleaned up rim vertices to match the reference images. Select the rim’s edge loop and create a series of extrusions to model the thruster’s cavity and propeller using the techniques learned while building the stabilizer. When you’re done, you can apply a bevel to the thruster’s top edge loop to create a border rim on the top faces. Select the three objects you created and go to Edit>Delete by Type>History to clean up their construction history. This bakes down all the modeling operations applied so far to the objects. On top of that, we also want to freeze each object’s transformation values to bake them as their new defaults. Go to Modify>Freeze Transformations. This helps keep all objects consistent in their transform attributes. Rename your objects ‘left_fuelTank_geo’, ‘left_thruster_geo’, and ‘left_stabilizer_geo’, respectively. Lastly to mirror these objects on the right side of the jetpack shell, we want to create copies with a negative “Scale X” value so that they are flipped across the YZ plane. Go to Edit>Duplicate Special [Options]. Reset the settings, then set Scale X to -1 and click Apply. Maya LT mirrors the objects, but it’s using their individual pivot instead of using one common pivot for all. Instead, group the original objects together and create a mirrored duplicate of that. Maya LT mirrors the group across the YZ plane along with the objects within, and maintains their relative positions. Freeze the transformations on the duplicated group to bake down its negative scale value, and rename the new objects accordingly. In the next movie, we’ll model the jetpack’s air intake and door panels.

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  1. Thanks for this tutorials..I am 55 years and beginner in Maya. Looking forward to further tutorials for me as a beginner

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