de.javagl.obj

Class ObjUtils

java.lang.Object

de.javagl.obj.ObjUtils

public class ObjUtils
extends Object

Utility methods for handling Objs.

Unless otherwise noted, none of the parameters to these methods may be null

Method Summary

Modifier and Type	Method and Description
static Obj	convertToRenderable(ReadableObj input) Convert the given ReadableObj into an Obj that has a structure appropriate for rendering it with OpenGL: Triangulate it Make the texture coordinates unique Make the normals unique Make the result vertex-indexed
static <T extends WritableObj> T	convertToRenderable(ReadableObj input, T output) Convert the given ReadableObj into an Obj that has a structure appropriate for rendering it with OpenGL: Triangulate it Make the texture coordinates unique Make the normals unique Make the result vertex-indexed
static String	createInfoString(ReadableObj obj) Create a multi-line, formatted string containing information about the given ReadableObj.
static Obj	groupToObj(ReadableObj input, ObjGroup inputGroup, List<Integer> vertexIndexMapping) Returns the given group of the given ReadableObj as a new Obj.
static <T extends WritableObj> T	groupToObj(ReadableObj input, ObjGroup inputGroup, List<Integer> vertexIndexMapping, T output) Stores the given group of the given ReadableObj in the given output WritableObj.
static Obj	makeNormalsUnique(ReadableObj input) Ensures that two vertices with different normals are actually two different vertices with different indices.
static <T extends WritableObj> T	makeNormalsUnique(ReadableObj input, List<Integer> indexMapping, T output) Ensures that two vertices with different normals are actually two different vertices with different indices.
static Obj	makeTexCoordsUnique(ReadableObj input) Ensures that two vertices with different texture coordinates are actually two different vertices with different indices.
static <T extends WritableObj> T	makeTexCoordsUnique(ReadableObj input, List<Integer> indexMapping, T output) Ensures that two vertices with different texture coordinates are actually two different vertices with different indices.
static Obj	makeVertexIndexed(ReadableObj input) Converts the given ReadableObj data into data that uses the same indices for vertices, texture coordinates and normals, and returns the result.
static <T extends WritableObj> T	makeVertexIndexed(ReadableObj input, T output) Converts the given ReadableObj data into data that uses the same indices for vertices, texture coordinates and normals, and stores the result in the given WritableObj.
static Obj	triangulate(ReadableObj input) Triangulates the given input ReadableObj and returns the result.
static <T extends WritableObj> T	triangulate(ReadableObj input, T output) Triangulates the given input ReadableObj and stores the result in the given WritableObj.

Methods inherited from class java.lang.Object

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

Method Detail

convertToRenderable

public static Obj convertToRenderable(ReadableObj input)

Convert the given ReadableObj into an Obj that has a structure appropriate for rendering it with OpenGL:

• Triangulate it
• Make the texture coordinates unique
• Make the normals unique
• Make the result vertex-indexed

Parameters:

input - The input ReadableObj

Returns:

The resulting Obj

convertToRenderable

public static <T extends WritableObj> T convertToRenderable(ReadableObj input,
                                                            T output)

Convert the given ReadableObj into an Obj that has a structure appropriate for rendering it with OpenGL:

• Triangulate it
• Make the texture coordinates unique
• Make the normals unique
• Make the result vertex-indexed

Type Parameters:

T - The type of the output

Parameters:

input - The input ReadableObj

output - The output WritableObj

Returns:

The given output

triangulate

public static Obj triangulate(ReadableObj input)

Triangulates the given input ReadableObj and returns the result.

This method will simply subdivide faces with more than 3 vertices so that all faces in the output will be triangles.

Parameters:

input - The input ReadableObj

Returns:

The resulting Obj

triangulate

public static <T extends WritableObj> T triangulate(ReadableObj input,
                                                    T output)

Triangulates the given input ReadableObj and stores the result in the given WritableObj.

This method will simply subdivide faces with more than 3 vertices so that all faces in the output will be triangles.

Type Parameters:

T - The type of the output

Parameters:

input - The input ReadableObj

output - The output WritableObj

Returns:

The given output

groupToObj

public static Obj groupToObj(ReadableObj input,
                             ObjGroup inputGroup,
                             List<Integer> vertexIndexMapping)

Returns the given group of the given ReadableObj as a new Obj.

The vertexIndexMapping may be null. If it is not null, vertexIndexMapping.get(i) afterwards stores the index that vertex i had in the input.

Parameters:

input - The input ReadableObj

inputGroup - The group of the input

vertexIndexMapping - The optional index mapping

Returns:

The resulting Obj

groupToObj

public static <T extends WritableObj> T groupToObj(ReadableObj input,
                                                   ObjGroup inputGroup,
                                                   List<Integer> vertexIndexMapping,
                                                   T output)

Stores the given group of the given ReadableObj in the given output WritableObj.

The vertexIndexMapping may be null. If it is not null, vertexIndexMapping.get(i) afterwards stores the index that vertex i had in the input.

Type Parameters:

T - The type of the output

Parameters:

input - The input ReadableObj

inputGroup - The group of the input

vertexIndexMapping - The optional index mapping

output - The output WritableObj

Returns:

The given output

makeTexCoordsUnique

public static Obj makeTexCoordsUnique(ReadableObj input)

Ensures that two vertices with different texture coordinates are actually two different vertices with different indices.

Two faces may reference the same vertex in the OBJ file. But different texture coordinates may be assigned to the same vertex in both faces. The vertex that requires two different properties will be be duplicated in the output, and the indices in one face will be updated appropriately.

This process solely operates on the indices of the properties. It will not check whether the value of two properties (with different indices) are actually equal.

Parameters:

input - The input ReadableObj

Returns:

The resulting Obj

makeTexCoordsUnique

public static <T extends WritableObj> T makeTexCoordsUnique(ReadableObj input,
                                                            List<Integer> indexMapping,
                                                            T output)

Ensures that two vertices with different texture coordinates are actually two different vertices with different indices.

Two faces may reference the same vertex in the OBJ file. But different texture coordinates may be assigned to the same vertex in both faces. The vertex that requires two different properties will be be duplicated in the output, and the indices in one face will be updated appropriately.

This process solely operates on the indices of the properties. It will not check whether the value of two properties (with different indices) are actually equal.
The indexMapping may be null. Otherwise it is assumed that it already contains the index mapping that was obtained by a call to groupToObj(ReadableObj, ObjGroup, List, WritableObj), and this mapping will be updated appropriately.

Type Parameters:

T - The type of the output

Parameters:

input - The input ReadableObj

indexMapping - The optional index mapping

output - The output WritableObj

Returns:

The given output

makeNormalsUnique

public static Obj makeNormalsUnique(ReadableObj input)

Ensures that two vertices with different normals are actually two different vertices with different indices.

Two faces may reference the same vertex in the OBJ file. But different normals may be assigned to the same vertex in both faces. The vertex that requires two different properties will be be duplicated in the output, and the indices in one face will be updated appropriately.

This process solely operates on the indices of the properties. It will not check whether the value of two properties (with different indices) are actually equal.

Parameters:

input - The input ReadableObj

Returns:

The resulting Obj

makeNormalsUnique

public static <T extends WritableObj> T makeNormalsUnique(ReadableObj input,
                                                          List<Integer> indexMapping,
                                                          T output)

Ensures that two vertices with different normals are actually two different vertices with different indices.

Two faces may reference the same vertex in the OBJ file. But different normals may be assigned to the same vertex in both faces. The vertex that requires two different properties will be be duplicated in the output, and the indices in one face will be updated appropriately.

This process solely operates on the indices of the properties. It will not check whether the value of two properties (with different indices) are actually equal.
The indexMapping may be null. Otherwise it is assumed that it already contains the index mapping that was obtained by a call to groupToObj(ReadableObj, ObjGroup, List, WritableObj), and this mapping will be updated appropriately.

Type Parameters:

T - The type of the output

Parameters:

input - The input ReadableObj

indexMapping - The optional index mapping

output - The output WritableObj

Returns:

The given output

makeVertexIndexed

public static Obj makeVertexIndexed(ReadableObj input)

Converts the given ReadableObj data into data that uses the same indices for vertices, texture coordinates and normals, and returns the result.

Note that the result may contain ambiguous texture coordinates and normals, unless they have been made unique in the input before with makeTexCoordsUnique(ReadableObj) and makeNormalsUnique(ReadableObj), respectively.

Parameters:

input - The input ReadableObj

Returns:

The resulting Obj

makeVertexIndexed

public static <T extends WritableObj> T makeVertexIndexed(ReadableObj input,
                                                          T output)

Converts the given ReadableObj data into data that uses the same indices for vertices, texture coordinates and normals, and stores the result in the given WritableObj.

Note that the result may contain ambiguous texture coordinates and normals, unless they have been made unique in the input before with makeTexCoordsUnique(ReadableObj) and makeNormalsUnique(ReadableObj), respectively.

Type Parameters:

T - The type of the output

Parameters:

input - The input ReadableObj

output - The output WritableObj

Returns:

The given output

createInfoString

public static String createInfoString(ReadableObj obj)

Create a multi-line, formatted string containing information about the given ReadableObj. This method is solely intended for debugging. It should not be considered as part of the public API. The exact output is not specified.

Parameters:

obj - The ReadableObj

Returns:

The info string