de.javagl.obj

Class ObjSplitting

java.lang.Object

de.javagl.obj.ObjSplitting

public class ObjSplitting
extends Object

Methods for splitting ReadableObj objects into multiple parts, based on different criteria.

Method Summary

Modifier and Type	Method and Description
static Map<String,Obj>	splitByGroups(ReadableObj obj) Split the given ReadableObj based on its groups.
static Map<String,Obj>	splitByMaterialGroups(ReadableObj obj) Split the given ReadableObj based on its material groups.
static List<Obj>	splitByMaxNumVertices(ReadableObj obj, int maxNumVertices) Split the given ReadableObj into Obj instances based on the given maximum number of vertices.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Method Detail

splitByGroups

public static Map<String,Obj> splitByGroups(ReadableObj obj)

Split the given ReadableObj based on its groups. This will create one Obj from each (non-empty) group in the given input.

Parameters:

obj - The input ReadableObj

Returns:

One Obj for each non-empty group of the given input

splitByMaterialGroups

public static Map<String,Obj> splitByMaterialGroups(ReadableObj obj)

Split the given ReadableObj based on its material groups. This will create one Obj from each (non-empty) material group in the given input.

Note that if the given OBJ does not contain any material groups (that is, when it does not refer to a material with a usemtl directive), then the resulting map will be empty.

Faces that are not associated with any material group will not be contained in the output.

Parameters:

obj - The input ReadableObj

Returns:

The mapping from material group names (corresponding to the usemtl directives in the input file) to the Obj that represents this material group.

splitByMaxNumVertices

public static List<Obj> splitByMaxNumVertices(ReadableObj obj,
                                              int maxNumVertices)

Split the given ReadableObj into Obj instances based on the given maximum number of vertices.

Note that this method will not split any faces in the given OBJ. So although the resulting parts will usually not have more than the given maximum number of vertices, this cannot be guaranteed: When there is a face in the input OBJ that has n vertices, the resulting parts will have at most maxNumVertices + n - 1 vertices. For example, if the given input contains only triangles, then the parts will have at most maxNumVertices + 2 vertices.

Many details about the splitting process that is used internally are intentionally not specified. This method is mainly intended for splitting a large Obj into parts that it may be rendered in environments that only allow a certain number of vertices (indices) per rendered object. For example, in order to create parts whose indices can be represented with an unsigned short value, this method may be called with maxNumVertices=65000.

Parameters:

obj - The input ReadableObj

maxNumVertices - The maximum number of vertices

Returns:

One Obj for each part.

Throws:

IllegalArgumentException - If the given number is smaller than 3.