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          SECTION 9.5                                                                    3D Artwork



          3D Lighting Scheme Dictionaries

          A 3D lighting scheme dictionary (PDF 1.7) specifies the lighting to apply to 3D
          artwork. The LS entry in the 3D view can include a 3D lighting scheme dictio-
          nary.

          Table 9.36 shows the entries in a 3D lighting scheme dictionary.

                          TABLE 9.44 Entries in a 3D lighting scheme dictionary
KEY                         TYPE          VALUE

Type                        name          (Optional) The type of PDF object that this dictionary describes; if
                                          present, must be 3DLightingScheme.

Subtype                     name          (Required) The style of lighting scheme described by this dictionary
                                          (see Table 9.45).

          Table 9.45 describes the supported lighting schemes. With the exception of the
          Artwork lighting style, all the lights specified below are infinite lights (also known
          as distant lights). Unlike lights from a point source, all rays from an infinite light
          source are emitted along a single direction vector. For lights specifying an ambi-
          ent term, this term is added to the diffuse color of an object’s material. All colors
          are specified in the DeviceRGB color space.

          When a style other than Artwork is used, only those lights described should be
          present; any lighting described in the artwork should not be used.

                                   TABLE 9.45 3D lighting scheme styles
          SCHEME          DESCRIPTION

          Artwork         Lights as specified in the 3D artwork. This has the same effect as if the
                          3D lighting scheme dictionary were omitted.

          None            No lights are used. That is, lighting specified in the 3D artwork is
                          ignored.

          White           Three blue-grey infinite lights, no ambient term
                            Light 1      Color: < 0.38, 0.38, 0.45 > Direction: < -2.0, -1.5, -0.5 >
                            Light 2      Color: < 0.6, 0.6, 0.67 > Direction: < 2.0, 1.1, -2.5 >
                            Light 3      Color: < 0.5, 0.5, 0.57 > Direction: < -0.5, 0.0, 2.0 >

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