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adjacency_filter(display) Filter adjacency_filter(display)

NAME

adjacency_filter - abstract class to load display data into unstructured grid form

DESCRIPTION

Adjacency_filter is an abstract class that takes as input a display_data object and loads the various geometry components into a vertex/geometric primitive ring structure. This ring structure consists of three lists: a list of node coordinates implicit ordered according to node number; a list of geometric primitives (lines, polygons, quadrilaterals, and triangle strips); and a list of links. The list of geometric primitives defines each primitive as an ordered list of nodes, while the link structure is a list of lists of geometric primitives that use each node. Special operators provide efficient searching or traversing across neighboring geometric primitives.

It is possible to control the loading of particular components of display data into the ring structure. For example, some algorithms only operate on polygons, so loading lines and triangle strips is not desirable. Also, some subclasses of adjacency_filter explicitly set which components to load, and may ignore the value set by the user.

NOTE: if loading polygons is enabled and loading triangle strips is disabled, then triangle strips are automatically converted into polygons.

SUPERCLASS

display_filter

INSTANCE VARIABLES

load_lines boolean to specify whether to load lines.

load_polygons boolean to specify whether to load polygons.

load_triangle_strips boolean to specify whether to load triangle strips.

build_links boolean to control whether or not to build links. If links are not built, then geometric primitive neighbor traversal is not possible.

MESSAGES

load_lines_on!/off! turn on/off the loading of lines. Default is on.

load_lines? get the value of the load_lines instance variable.

load_lines= value set the value of the load_lines instance variable.

load_polygons_on!/off! turn on/off the loading of polygons. Default is on.

load_polygons? get the value of the load_polygons instance variable.

load_polygons= value set the value of the load_polygons instance variable.

load_triangle_strips_on!/off! turn on/off the loading of triangle_strips. Default is on.

load_triangle_strips? get the value of the load_triangle_strips instance variable.

load_triangle_strips= value set the value of the load_triangle_strips instance variable.

turn on/off the building of the links array. In some cases only the loading/conversion of data is useful, not the traversal operators.

turns on the loading of all geometric primitives (lines, polygons, triangle strips)

turns off the loading of all geometric primitives (lines, polygons, triangle strips)

get the value of the build_links boolean.

load_data internal method to cause data to load

free_data internal method to free previously loaded data.

EXAMPLE

Adjacency filter is an abstract class and is never directly instantiated. Instead see an example for one of its subclasses such as triangle_strip_filter.