Module org.dyn4j
Package org.dyn4j.collision

Class TypeFilter

  • All Implemented Interfaces:
    Filter
    public abstract class TypeFilter
extends Object
implements Filter
    A base implementation of a class hierarchy Fixture Filter.

    This class is not used directly but instead extended by marker classes (see example below).

    This filter is designed to allow a hierarchy of categories where each category can collide with it's parents and it's descendants, but not it's siblings.

    For example, imagine we have the following hierarchy of categories: 

                 Root Category
             /           \
        Category1     Category2
        /      \
 Category 3  Category 4
    This hierarchy allows the following:
    • A fixture with the Root category can collide with anything.
    • A fixture with the Category1 category can collide with the Category1, Category3, Category4, and Root categories. (i.e. not Category2)
    • A fixture with the Category2 category can collide with the Category2 and Root categories only.
    • A fixture with the Category3 category can collide with the Category3, Category1, and Root categories.
    • A fixture with the Category4 category can collide with the Category4, Category1, and Root categories.

    To implement this you create a class for each category (you could put these in their own class file, its done this way for brevity): 

     public final class Categories {
        private static class Root extends TypeFilter {}
        private static class Category1 extends Root {}
        private static class Category2 extends Root {}
        private static class Category3 extends Category1 {}
        private static class Category4 extends Category1 {}
        
        public static final TypeFilter ROOT = new Root();
        public static final TypeFilter CATEGORY1 = new Category1();
        public static final TypeFilter CATEGORY2 = new Category2();
        public static final TypeFilter CATEGORY3 = new Category3();
        public static final TypeFilter CATEGORY4 = new Category4();
 }
 // then set the filter on the fixtures
 fixture.setFilter(Categories.ROOT);
 // or
 fixture.setFilter(Categories.CATEGORY1);
    Since:
    3.0.2
    Version:
    3.0.2
    Author:
    William Bittle

    • Constructor Detail

      • TypeFilter

        public TypeFilter()

    • Method Detail

      • isAllowed

        public boolean isAllowed​(Filter filter)
        Returns true under the following conditions:
        1. If this filter is the same type as the given filter.
        2. If this filter type is a descendant of the given filter's type.
        3. If the given filter's type is a descendant of this filter's type.
        If the given filter is not of type TypeFilter then false is returned.

        If the given filter is null then false is returned.

        Specified by:
        isAllowed in interface Filter
        Parameters:
        filter - the other filter
        Returns:
        boolean