Converting a NURBS Model to Polygons
Some people prefer to model on NURBS curves and either create poly surfaces or convert to polygons after the entire model is done with NURBS surfaces. Ultimately, you’ll find your own workflow preference, but it helps greatly if you’re comfortable using all surfacing methods. Most modelers choose one way or another but are familiar with both methodologies. In the following section, you’ll convert a NURBS model to polygons.
Try This Convert a NURBS modeled axe into a poly model like one that might be needed in a game.
Open axe_model_v1.mb in the Scenes folder of the Axe project on the CD. The toughest part of this simple process is getting the poly model to follow all the curves in the axe with fidelity, so you’ll have to convert parts of the axe differently. Follow these steps:
Figure 5-17: A faithful high-poly conversion (on the right) of the NURBS axe (on the left)
1. Grab the handle, and choose Modify ⇒ Convert ⇒ NURBS to Polygons ❒. Use the default presets. If need be, reestablish your settings by choosing Edit ⇒ Reset Settings; the handle converts well to polygons. Click Apply, and a poly version of the axe handle appears on top of the NURBS version. Move it eight units to the right to get it out of the way. You’ll move the other parts 8 units as well to assemble the poly axe properly.
2. Select the back part of the axe head. All those surfaces are grouped together to make selection easy. The default settings will work for this part as well, so click Apply and move the resulting model eight units to the left.
3. The front of the axe head holds a lot of different arcs, so you’ll have to create it with finer controls. Change Fractional Tolerance from 0.01 to 0.0005. This yields more polygons but finer curved surfaces. Figure 5-17 shows the result.
If you were following this process for a conventional game engine, you’d normally be restricted to a low number of polygons, and your axe design would be different to better handle a low poly count.