TinyXPD, dependency-free and header-only C++11 XGen XPD cache I/O library.

TinyXPD is a simple library to read/write XGen XPD cache file.

Currently reading/writing spline XPD data is implemented.

Requirement

• C++11 compiler

Supported platform

• macOS
• Linux
• Windows(Visual Studio 2017 or later)
• Android
• iOS
• Big endian machine(e.g. POWER)

Supported XPD version

• XPD3(~Maya 2018)

Parsing XPD file

+-----------------------------+   |\
| XPD header                  |   |
+-----------------------------+   | XPD data
|                             |   |
| XPD prim data               |   |
|                             |   |
|                             |   |
+-----------------------------+   |/

XPDHeader contains header information and the list of data offset from the beginning of a XPD data.

Whole XPD data is supplied by the app user(ParseXPDHeaderFromMemory API), or read from a file(ParseXPDFromFile). ParseXPDFromFile API is handy but consumes memory. If you want to open large XPD file(e.g. 1GB or more), consider using ParseXPDHeaderFromMemory API(with mmap-ping a XPD data).

// Do this only in **one** .cc file.
#define TINY_XPD_IMPLEMENTATION
#include "tiny_xpd.h"

std::string filename = "sample.xpd";

XPDHeader xpd_header;
std::vector<uint8_t> xpd_data;
std::string err;

bool ret = ParseXPDFromFile(filename, &xpd_header, &xpd_data, &err);

// From memory(stream) version.
// Fill xpd_data by yourself in some way.
// xpd_data = ...
// bool ret = ParseXPDHeader(xpd_data.data(), xpd_data.size(), &xpd_header, &err);

if (!err.empty()) {
  std::cerr << err << std::endl;
}

if (!ret) {
  std::cerr << "Failed to parse XPD" << std::endl;
}

// See `xpd_reader_example.cc` for how to access primitive data.

Examples

• examples/simple_sprine_writer Simple spline XPD writer example.

Generating XPD file from Maya

You can use xgSplineDataToXpd sample plug-in(located in /usr/autodesk/maya/plug-ins/xgen/plug-ins/ or write your own XPD writer plugin.

Note on importing XPD in legacy XGen

It looks legaxy XGen's From XPD File feature expects that spline data layout is as defined in xgSplineDataToXpd sample code.

Per CV width

Data layout used in xgSplineDataToXpd example does not support exporting per-CV width. It can only support constant width over CVs(strand), and taper. width ramp is not support.

If you need a spline curve with varying width, you may need to write your own XGen loader(generator) plugin, or bake taper parameter to width ramp value and export/import it in other data format(e.g. python + JSON).

Supported types

• Curve(XGen interactive grooming splines)
• Point(xuv)

TODO

• Support xuv format.

License

MIT license.