3D Graphics Programming with QuickDraw 3D 1.5.4

Subdivision Styles

Labels

ASCII: SubdivisionStyle
Binary: sbdv ( = 0x7364636C )

Subdivision Method Enum Data Type

Constant: 0x00000000
WorldSpace: 0x00000001
ScreenSpace: 0x00000002

There are two data formats.

First Data Format



 
SubdivisionMethodEnum                   subdivisionMethod

Float32                                 value1

subdivisionMethod: The value in this field must be one of the specifiers WorldSpace or ScreenSpace . A value of WorldSpace indicates that the renderer subdivides a curve (or surface) into polylines (or polygons) whose sides have a world-space length that is at most as large as the value specified in the value1 field. A value of ScreenSpace indicates that the renderer subdivides a curve (or surface) into polylines (or polygons) whose sides have a length that is at most as large as the number of pixels specified in the value1 field.
value1: For world-space subdivision, the maximum length of a polyline segment (or polygon side) into which a curve (or surface) is subdivided. For screen-space subdivision, the maximum number of pixels in a polyline segment (or polygon side) into which a curve (or surface) is subdivided. The value in this field should be greater than 0.

Data Size

Second Data Format



 
SubdivisionMethodEnum                   subdivisionMethod

Uns32                                   value1

Uns32                                   value2

subdivisionMethod: The value in this field must be the specifier Constant . This value indicates that the renderer subdivides a curve into a number of polyline segments and a surface into a mesh of polygons.
value1: The number of polylines into which a curve should be subdivided, or the number of vertices in the u parametric direction of the polygonal mesh into which a surface is divided. The value in this field should be greater than 0.
value2: The number of vertices in the v parametric direction of the polygonal mesh into which a surface is divided. The value in this field should be greater than 0.

Data Size

Description

A scene's subdivision style determines how a renderer decomposes smooth curves and surfaces into polylines and polygonal meshes for display purposes. Different specifiers and numerical values determine different degrees of fineness of approximation.

Parent Hierarchy

Shared, shape, style.

Parent Objects

None.

Child Objects

None.

Example



 
BeginGroup ( DisplayGroup ( ) 

    SubdivisionStyle ( Constant 32 32 )

    Ellipsoid ( ... )

    )

    Container (

        SubdivisionStyle ( WorldSpace 12 )

        Box ( ... )

    )

EndGroup ( )