Add Entity.getChildren

src/entity.zig

@@ -22,6 +22,7 @@ pub const EntityError = error{
     GenMismatch,
     /// Entity is not alive.
     IsNotAlive,
+    // TODO: Rename this to `EntityMissing` and similar, use it elsewhere in the code.
 };
 
 /// An `Entity` is an `Id` which represents a "thing" within the world. This
@@ -259,6 +260,11 @@ pub fn Entity(comptime ctx: anytype) type {
             return if (result != 0) fromRaw(self.world, result) else null;
         }
 
+        /// Returns an iterator that yields each of this `Entity`s children.
+        pub fn getChildren(self: Self) World(ctx).TermIterator {
+            return self.world.term(.{ c.EcsChildOf, self });
+        }
+
         /// Returns an iterator that yields each of the targets of the
         /// specified `relation` that this `Entity` has, if any.
         pub fn getTargets(self: Self, relation: anytype) TargetIterator {