Advanced Maya Texturing and Lighting- P7

Advanced Maya Texturing and Lighting- P7: I should stress that I am self-taught. In 1994, I sat down at a spare seat of AliasPowerAnimator 5.1 and started hacking away. After several years and various trials byfire, 3D became a livelihood, a love, and an obsession. Along the way, I was fortunateenough to work with many talented artists at Buena Vista Visual Effects and PacificData Images. In 2000, I switched from PowerAnimator to Maya and have since loggedtens of thousands of hours with the subject of this book....
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Advanced Maya Texturing and Lighting- P7appear. That is, the upper edge of the texture is pinched into a single point, as is thelower. For example, in Figure 5.24 a checker texture is mapped to a surface shadermaterial as a spherical projection. The top and bottom portion of the checker is col-lapsed at the poles. A similar problem occurs with a nurBs sphere; even though allnurBs surfaces have four edges, two of the edges are collapsed into single points atthe sphere’s top and bottom pole. 159 ■ 2 D T e x T u r e p roj e c T i o n o p T i o n sFigure 5.23 Planar projections mapped to various primitive surfaces. This scene is included on the CD as proj_plane.ma. Note: Although always visible, a Projection utility’s V Angle attribute is functional only for a Spherical projection type. U Angle is functional only for Spherical and Cylindrical projections.160A p p ly i n g 3 D T e x T u r e s A n D p roj e c T i o n s ■ Figure 5.24 (Left) A Spherical projection with default settings is applied to a sphere. (Right) The Spherical projection’s U Angle is set to 360 and its V Angle is set to 180. This scene is included on the CD as proj_spherical.ma. Ball places the texture inside a projection sphere. The projection pinches the texture at only one pole. A real-world equivalent is a blanket draped over a ball with the blan- ket’s four corners twisted together at one spot. The pole is indicated by the diamond- shaped uV origin symbol on the projection icon (see Figure 5.25).5:chapter Figure 5.25 (Left) A Ball projection is applied to a sphere. (Middle) The Ball projection icon. (Right) The test bitmap. This scene is included on the CD as proj_ball.ma. Cylindrical places the texture inside a cylinder. The left and right edges of the texture will meet if the projection’s u Angle is set to 360 degrees. The cylindrical type creates two pinched poles at the top and bottom of the projection (see Figure 5.26).Figure 5.26 A Cylindrical projection applied to a sphere. This scene is included on the CDas proj_cylinder.ma.Cubic places a texture onto the six faces of a cube (see Figure 5.27). 161 ■ 2 D T e x T u r e p roj e c T i o n o p T i o n sFigure 5.27 A Cubic projection applied to a sphere. This scene is included on the CD as proj_cubic.ma.Concentric randomly selects vertical slices from the texture and projects them in aconcentric pattern.TriPlanar projects the texture along three planes based on the surface normal of theobject that is affected.Perspective projects the texture from the view of a camera (see Figure 5.28). For thisto work, a camera must be selected from a drop-down list provided by the link Tocamera attribute (found in the camera projection Attributes section of the projec-tion utility’s Attribute editor tab). The projection icon will take the form of a camerafrustum but will not be aligned to the chosen camera in 3D space. The frustum canbe “snapped” to the camera, however, by connecting the Translate, scale, and rotateattributes of the camera’s transform node to the same attributes of the 3D placementnode connected to the projection utility node. (For more information on custom con-nections, see chapter 6.) Figure 5.28 A Perspective projection applied to a series of spheres. This scene is included on the CD as proj_persp.ma. Placing Placement Boxes and Projection Icons The translation, scale, and rotation of a 3D placement utility’s placement box or pro-162 ...