3D Graphics Programming with QuickDraw 3D 1.5.4

Vertex Attribute Set Lists

Labels

ASCII: VertexAttributeSetList
Binary: vasl ( = 0x7661736C )

Data Format



 
Uns32               nObjects

PackingEnum         packing

Uns32               nIndices

Uns                 indices[nIndices]

nObjects: The number of vertices of the parent geometric object.
packing: See "Face Attribute Set Lists" , for a complete explanation of this field.
nIndices: Size of the following array. See "Face Attribute Set Lists" , for a complete explanation of this field.
indices[]: An array of vertex indices. See "Face Attribute Set Lists" , for a complete explanation of this field.

Data Size

16 + nIndices * sizeof(Uns) + padding

Description

A vertex attribute set list is used to assign sets of attributes separately and selectively to the vertices of a verticed geometric object. Among the primitive metafile geometric objects, the following have vertices: general polygons, lines, meshes, polygons, polylines, triangles, and trigrids.

The index used to enumerate the vertices of an object of one of these types is described in the section on objects of that type. To recapitulate, in all cases the vertices are enumerated in the order of their occurrence in the specification of the parent geometric object. In the case of a general polygon, the index does not distinguish between contours.

Parent Hierarchy

Data, attribute set list.

Parent Objects

General polygon, line, mesh, polygon, polyline, triangle, trigrid. A vertex attribute set list always has a parent object.

Child Objects

Attribute sets (required). See "Face Attribute Set Lists" , for a complete explanation of how child objects are correlated with aspects of the parent geometric object.

Example



 
Container ( 

    GeneralPolygon (                # parent geometric object

        2                           # nContours

        #contour 0

        3                           # nVertices, contour 0

        -1 0 0                      # vertex 0

        1 0 0                       # vertex 1

        0 1.7 0                     # vertex 2

        #contour 1

        3                           # nVertices, contour 1

        -1 0.4 0                    # vertex 3

        1 0.4 0                     # vertex 4

        0 2.1 0                     # vertex 5

    )

    Container ( 

        VertexAttributeSetList ( 6 Exclude 2 0 4 )          # set list

        Container (                                         # child objects

            AttributeSet ( )                    # vertex 1 (contour 0)

            DiffuseColor ( 0 0 1 )

        )

        Container ( 

            AttributeSet ( )                    # vertex 2 (contour 0)

            DiffuseColor ( 0 1 1 )

        )

        Container ( 

            AttributeSet ( )                    # vertex 3 (contour 1)

            DiffuseColor ( 1 0 1 )

        )

        Container ( 

            AttributeSet ( )                    # vertex 5 (contour 1)

            DiffuseColor ( 1 1 0 )

        )

    )

    Container ( 

        AttributeSet ( )

        DiffuseColor ( 1 1 1 )

    )

)