Fixes:
* General:
- Was assuming that positions/normals/UVs are always `float`, and colors
are always `uchar`. But e.g. positions are sometimes doubles, or colors
are floats etc.
- Was assuming that `face` element is always just a single vertex indices
property. But some files have more arbitrary properties per-face.
* ASCII importer:
- Was assuming that file elements are always in this order: `vertex`,
`face`, `edge`. That is not necessarily the case.
- Was only handling space character as separator, but not other
whitespace e.g. tab.
- Was not checking for partially present properties (e.g. if just `nx` is
present but not `ny` and `nz`, it was still assuming whole normal is there).
* Binary importer:
- Was assuming that faces are always 1-byte list size and 4-byte indices.
- Was assuming that edge vertex indices are always 4-byte.
For the assumptions above, it often lead to either crashes, garbage data
or not detecting presence of a vertex component. E.g. binary importer was
just always reading 4 bytes for vertex indices, but if a file has 2 byte
indices then that would read too much, and then later on would start reading
garbage. ASCII importer was doing out-of-bounds reads into properties array
if some assumptions were not correct, etc.
Improvements:
- Some ply files use different property type names, e.g. `float32`,
`uint16` or `int8` instead of `float`, `ushort`, `char`; now that is
supported too.
- Handles `tristrips` element. Some files out there do not have `face` but
rather has a triangle strip, internally using -1 indices for strip restarts.
Performance:
While doing the above fixes/improvements, in order to fix some things it was
more convenient to also make them more performant :) Now it avoids splitting
each ASCII line into a vector of `std::string` objects, for example, or
reading a binary file in tiny chunks.
Generally this is now 2x-4x faster than the previous state of C++ importer.
The code has changed quite a bit to achieve both the fixes and performance:
- Instead of separate files for ASCII and Binary reading, they are now both
in `ply_import_data.cc/hh`. Reason is that all of the "find correct property
indices" logic is the same between both (and that bit was mostly missing
previously).
- Instead of using raw C++ `fstream` object and reading line by line (which
in turn reads one byte at a time) or reading field by field, now there's a
`ply_import_buffer.cc/hh` that reads in 64KB chunks and does any needed
logic for the ASCII/header part to properly split into lines. This avoids
all the mutex locking, locale lookups, C++ abstraction layers overhead
that C++ iostreams have when doing a ton of tiny reads.
Tests:
Extended test coverage with new files (comitted in svn revision 63274).
11 new "situations", in both ascii and binary forms. Additionally, now also
has a Big Endian binary file to test; BE codepath was completely untested
before.
Overall reworked the tests so that they don't do the whole "load dummy
blend file, import ply file on top, go over meshes, check them", but rather
do a simpler "run ply importer logic that fills in PlyData structure, check
that". The followup conversion to blender meshes is fairly trivial and the
tests were not really covering that in a useful way.
Pull Request: https://projects.blender.org/blender/blender/pulls/105842
6c6edaf513