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Tutorial: Erecting a Polygon Building

In this simple tutorial, you will use the Polygon Duplication and Transformation tools to create a believable polygonal building simply and easily (see Figure 7.38).

Figure 7.38 The completed polygonal building.

1. Start with a Primitive Cube.

Get a primitive cube and scale it to be twice as tall as it is wide. Then use the Effect->Subdivide command to chop it into more polygons that you can use to model in detail. Set the Polygon Subdivision to 8 in X, 0 in Z (we don't need detail on the side of the building), and 16 in Y to create a lot of top to bottom detail. These settings will create many new polygons we can duplicate and transform to make windows, exterior detail, doors, and so on.

2. Add in Roof Detail.

Use the G supra key (Select by Raycast) to select all the polygons on the top, front row of the building, but not the roof (see Figure 7.39).

Figure 7.39 The scaled cube with the subdivision and roof polygons selected.

Make sure you are in the Model module and enter POL mode to work on selected groups of polygons only. Choose the Duplicate->Immediate command to make a new group of polygons, and then activate the TransY menu cell. Set the Translation mode to LCL (local mode) so that the polygons translate on their local axis, where Y is along the normal.

Translate the group so that it extends in front as a roof overhang.

When done, select the top row on the next side of the building, and repeat. Create a ledge along the top of each side.

Now we'll create a stepped roof line. Deselect all the polygons with the Y supra key and the middle mouse button, and select only the top roof polygons. Deselect the single polygons on the left and right edge of the roof.

Translate all the selected roof polygons up a few units above the roof ledge, creating an angle at the left and right edges.

Duplicate the selected polygons and translate them up in Y a bit to form a roof step. By selecting fewer roof polygons and then alternating between translating them up without duplicating them first, you can make a pattern of sloped and stepped roof segments as in Figure 7.40.

Figure 7.40 The building with a polygonal stepped roof line.

3. Add in Front Detail.

Deselect all the polygons, and then select a strip of polygons running top to bottom along the front of the building, two polygons in from the left edge. Select a symmetrical strip two polygons in from the right edge.

Duplicate the selected polygons and translate them in Y to extend a solid concrete detail along the front of the building.

Add a similar strip of exterior detail in the exact center column of polygons if you want.

4. Add Windows.

Start by selecting only every other polygon in the rows between the edges of the building and the exterior detail you just made. Don't select polygons that touch each other or share a vertex.

Dolly in (supra key P) in the Perspective view to be tight on one window so you can precisely adjust your work.

Use Duplicate->Immediate to create new polygons around the windows, and then scale the selected polygons in X and Z to become slightly smaller, leaving a window frame. Translate the selected polygons slightly into the building.

Duplicate them again, but this time only translate them into the building to recess the windows into the face of the building (see Figure 7.41).

Figure 7.41 One window, duplicated and recessed.

Dolly out to see that the changes you made to the polygon you viewed were also made to all the other selected window polygons. This means that you can add detail to a great number of polygons at once, saving time and effort. You may wish to turn smoothing off to see your building more accurately; do so by entering the Info->Selection dialog and clicking the Faceted radio button.

As in any construction site, your building is finished but a mess. To remove all the unneeded polygons in the building, use the Effect->Cleanup command. In the Polygon Cleanup dialog box that it brings up, check the "Merge Polygons if angle smaller than" option and hit Ok (see Figure 7.42). You can check your work against the scene named PolyBuilding on the courseware CD-ROM.

Figure 7.42 The completed Wireframe building.

Polygon Breakup

Ordinarily neighboring polygons are always connected at each edge because they actually share that edge, like Siamese twins perpetually joined. In some cases, however, you may want each polygon to have its very own edges, unshared with any other polygon in the mesh. Reasons for this include a desire to offset some polygons, remove some polygons, or scale some polygons leaving gaps in the model. An even more common purpose is that when you plan to blow up a polygon model with the Explode tool, each polygon must be disconnected from its neighbors so that it can fly apart on its own as the mesh blows into small bits.

The Polygon->Breakup tool in the Model module fulfills this role. When it is activated, you can pick a polygon mesh. The mesh flashes a different color to indicate that the effect has run, and a new object is created with the same polygonal structure as the original, but with no shared edges (see Figure 7.43).

Figure 7.43 The building model, after breakup, with all polygons translated in Y to show the Exploded view.


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