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Using the UV projection commands is relatively straightforward; however, understanding how to apply the commands in different situations might take some time. Familiarity will come with practice and time. The purpose of the commands is to select groups of faces and project new UV coordinates onto them that can then be maneuvered in the UV Texture Editor. With that in mind, we will now go over the different options available to use. The projection commands include:
Planar Mapping (Edit Polygons > Texture > Planar Mapping) Planar Mapping will project UVs onto the selected faces from a 3D projection object in the shape of a flat plane (Figure 3.2). In the projection options, the direction of the planar projection can be set to one of the orthographic directions (X, Y, or Z), or it can be projected from the angle of your camera.
Figure 3.2 Planar Mapping projects UVs on the selected geometry from a flat plane. Shown here are the UV result (left) and the texture result (right).
Cylindrical Mapping (Edit Polygons > Texture > Cylindrical Mapping) Cylindrical Mapping will project UVs onto the selected faces from a 3D projection object in the shape of a cylinder (Figure 3.3). Obviously, this is most useful for objects of a cylindrical shape. In the options found in the Channel Box, you can adjust how much of a full cylinder is projected.
Figure 3.3 Cylindrical Mapping projects UVs on the selected geometry from a cylindrical shape.The UV result (left) and texture result (right) are shown.
Spherical Mapping (Edit Polygons > Texture > Spherical Mapping) The projection results from Spherical Mapping are, as you would expect, useful for sphere-shaped objects. As with the rest, a 3D projection object in the shape of a sphere will be created (Figure 3.4). You can adjust its creation options to determine the angle of projection around the object.
Figure 3.4 Spherical Mapping projects UVs on the selected geometry from a spherical shape.The UV result (left) and texture result (right) are shown.
Automatic Mapping (Edit Polygons > Texture > Automatic Mapping) Contrary to the previous projection commands, Automatic Mapping will try to map the selected geometry as cleanly as possible without using any sort of 3D objects from which to project. This command will divide the selected faces based on an angle and the number of projection directions you determine in the options, and then it will planar map them. It will then lay them out straight (Figure 3.5). This can be handy for irregularly shaped objects.
Figure 3.5 Automatic Mapping projects UVs from multiple directions to unwrap the selected geometry.The UV result (left) and texture result (right) are shown.
I like to use the Automatic Mapping projection command for most organic shapes. However, projecting the UVs is not the only step involved in readying a piece of geometry for texturing. UV Projection is only the first step in the process. There is still a matter of efficiently laying out these UVs. That is where the UV Texture Editor comes into use. Using the commands in the UV Texture Editor control panel, you can adjust and rearrange the projected UVs to lay out as efficiently as possible within the upperright grid square of the visible area. The upper-right part of the grid is where your textures will be placed (Figure 3.6). This is part of the process that will come more easily with practice.
Figure 3.6 A UV layout in place in the UV Texture Editor
The UV Texture Editor (Window > UV Texture Editor) is where you perform the sometimes-tedious action of arranging your UV layout. Let’s go over some of the more common commands found in the UV Texture Editor toolbar and menus.
Flip UVs (UV Texture Editor > Polygons > Flip UVs) This command will flip a group of selected UVs 180 degrees in either the U or V directions.
Rotate UVs (UV Texture Editor > Polygons > Rotate UVs) This command will rotate a group of selected UVs 45 degrees in either the U or V direction.
Align UVs (UV Texture Editor > Polygons > Align UVs) The Align UVs button allows you to align the selected UVs in a row, using the maximum or minimum value in the U or V direction as the value to which you align.
Cut UVs (UV Texture Editor > Polygons > Cut UVs) The Cut UVs command will separate the UVs of the selected edge(s).
Sew UVs (UV Texture Editor > Polygons > Sew UVs) The Sew UVs is the opposite of Cut UVs and will merge the UVs of the selected adjacent edge(s).
Move and Sew UVs (UV Texture Editor > Polygons > Move and Sew UVs) This is the same as the Sew UVs command, except it will move the entire UV shell of the selected edge instead of stretching the UVs across the editor when the merging edges are not close to each other in the editor. A UV Shell is a grouping of UVs in the UV Texture Editor. UV Snapshot (UV Texture Editor > Polygons > UV Snapshot) The UV Snapshot command is what you will use once your UV layout is complete. It will save an image of your UV layout to use in a paint program, such as Photoshop, as a guide for your texture. The options allow you to set the file format and resolution of the image that is created.
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Created: March 27, 2003
Revised: January 4, 2005
URL: http://webreference.com/graphics/game/1
