Packing UVs
After the objects are unwrapped, you have to “pack” them, which is the process in which you put together all the UVs in a single workspace so that they don’t overlap each other. The purpose is that instead of having a different texture for each object, you can have the whole character textured with a single image, so each part of it will occupy a part of the UV Map.
Figure 8.10 shows what the finished UVs will look like all together, which you’ll learn how to do in this section.
Figure 8.10 The packed UVs for Jim, shown with different colors for each object so you can see how they are distributed
With all these objects in one place, a single texture will be used for the whole character. As you can see in Figure 8.10, the face takes most of the texture space. There are also some spaces between objects: you can spend more time to fill the whole texture space and have a more efficient texture, but you should always leave a little space between UV islands, so when you paint they can have a little bleeding, otherwise you may see areas adjacent to the seams that weren’t painted.
There are several ways to pack UVs; let’s discuss a few of the most popular methods. The easiest way to pack UVs is to have everything inside the same mesh, so you can take islands, move them, rotate them, and scale them very easily in order to make them all fit together in the same texture space. This can be done, for example, with models that are made of numerous objects with no modifiers (such as Mirror or Solidify) applied; otherwise, you’ll lose the modifiers’ effects in the process. If there are no modifiers, you can select all the objects, press Ctrl + J to join them all in the same mesh, and then start packing their UVs. After the packing is done, you can export the UVs (you’ll learn how to do this in the next chapter) and separate them again if necessary.
A downside of this method is that when you join meshes and separate them again, you’ll lose their origins (pivot points) and they’ll all be in the position of the active mesh’s origin when you join them. In Chapter 11, Character Rigging, you’ll learn how to change the origin of an object.
Tip
Blender even provides tools for packing UVs when they’re all together in a single object: Average Islands Scale and Pack Islands. Average Islands (Ctrl + A) will scale the selected islands so they have a size that is relative to the size the faces have in the 3D model. Pack Islands (Ctrl + P) will scale and place the selected islands automatically so they take the largest space possible inside the UVs space.
Another packing method is to use a feature in Blender that allows you to see the UVs of other meshes in the UV/Image Editor, even though you can only adjust the UVs of the currently active object in Edit Mode. Here’s how it works: You select several objects with Shift + RMB. The last object selected is the active one. In Edit Mode, adjust the UVs and, in the UV/Image Editor, go to the header and activate the Draw Other Objects option in the View menu. Even though you will only be able to adjust the UVs for the active object, the rest of the selected objects’ UVs will also be shown.
The quick way to switch between objects is to press Tab to exit from Edit Mode and press Shift and right click the next object you want to adjust. Enter Edit Mode again, and that adjusted object will be the active object while keeping all of the objects selected. This is probably the most popular method of packing when you have objects with modifiers that you can’t join together, and this is how I did the packing for Jim’s UVs.