TDSLoader: remove readString maxLength

[tomsoftware]

• removed readString maxLength that is not defined by 3ds spec
• clean up code

Description

***removed maxLength ***

The using of a max-length when reading strings from a Chunk is not defined in the spec:

Format is "ASCIIZ" - no max 64
http://paulbourke.net/dataformats/3ds/
or
http://www.martinreddy.net/gfx/3d/3DS.spec

first item of Subchunk 4000 is an ASCIIZ string of the objects name.
ASCIIZ means a string of charakters ended by a zero.

This leads to problems parsing files with e.g. NameObjects having name-length > 64

I think this issue was intudused by the source implementation using for that code, that is a poor C implementation using fixed size char buffers to store the names
https://github.com/hoopoe/lib3ds/blob/f8cfd93e7a4f81feeb8473f0b73b0397e9ebf996/src/lib3ds_file.c#L226
and needs to prevent buffer-overflow

Other implementations do not use this max-length

• assimp: cpp
  https://github.com/assimp/assimp/blob/3e4cca4d2fcffb78385c09a3910824d84a8b10a3/code/AssetLib/3DS/3DSLoader.cpp#L325
• FreeCAD: python
  https://github.com/FreeCAD/FreeCAD/blob/master/src/Mod/Arch/Dice3DS/dom3ds.py

*** clean up ***
the original code uses a "global" read-position indicator and functions changing this - that is quite complicated

[Mugen87]

/ping @tentone

[Mugen87]

Your change breaks the official example:

https://raw.githack.com/tomsoftware/three.js/TDSLoader-fix-readString/examples/webgl_loader_3ds.html

[tomsoftware]

sorry... for the missing "{" in the first commit.
-> is there a test set of .3ds files?

[tentone]

Change looks good! Thanks!

I can confirm that lib3ds was used as a reference for the initial version.

[mrdoob]

Thanks!