simisa

A Python module to read and write files used with MSTS and Open Rails.

This module has a similar API to Python's built-in json module. When loading files, this module handles compression and text/binary formats of the SIMISA container seamlessly. It's also not at all sensitive to whitespace formatting in STF text files.

List of companion modules:

• shapeedit - provides a wrapper for modifying the shape data structure safely.
• trackshape-utils - offers additional utilities for working with track shapes.

Installation

Install from PyPI

pip install --upgrade simisa

Install from wheel

If you have downloaded a .whl file from the Releases page, install it with:

pip install path/to/simisa-<version>‑py3‑none‑any.whl

Replace <version> with the actual version number in the filename.

Install from source

git clone https://github.com/pgroenbaek/simisa.git
pip install --upgrade ./simisa

Usage

Not all file types used with MSTS and Open Rails are currently implemented. You can find the list of supported file types and whether reading/writing is supported for each file type in the table below.

Shorthand	Full module name	File type	Read files	Write files
s	shape	.s	Yes	Yes
t	terrain	.t	Yes	Yes
w	world	.w	Yes	Yes
rdb	roaddatabase	.rdb	Yes	No
tdb	trackdatabase	.tdb	Yes	No
tsection	tracksections	.dat (tsection.dat)	Yes	No

Reading files

Files on disk can be read using the .load() function of each submodule. This function looks deceptively simple from the outside.

Under the hood, .load() seamlessly takes care of handling compression and text/binary format based on information found in the file header.

from simisa import s, t, w, rdb, tdb, tsection

shape_obj = s.load("path/to/shapefile.s")
terrain_obj = t.load("path/to/terrainfile.t")
world_obj = w.load("path/to/worldfile.w")
rdb_obj = rdb.load("path/to/roaddatabasefile.rdb")
tdb_obj = tdb.load("path/to/trackdatabasefile.tdb")
tsection_obj = tsection.load("path/to/tsection.dat")

To read an in-memory text string, the .loads() function can be used instead. This function takes a string as input and returns the corresponding object.

Compressed or binary data is not supported using the .loads() function.

from simisa import s, t, w, rdb, tdb, tsection

shape_obj = s.loads(shape_text)
terrain_obj = t.loads(terrain_text)
world_obj = w.loads(world_text)
rdb_obj = rdb.loads(rdb_text)
tdb_obj = tdb.loads(tdb_text)
tsection_obj = tsection.loads(tsection_text)

These functions are also not sensitive to unexpected whitespace formatting in STF files, such as extra newlines, tabs and spaces in odd places that can make other tools choke.

Writing files

Uncompressed

To write uncompressed STF text data to a file on disk:

from simisa import s, t, w

s.dump(shape_obj, "path/to/shapefile.s")
t.dump(terrain_obj, "path/to/terrainfile.t")
w.dump(world_obj, "path/to/worldfile.w")

To write uncompressed STF text data to an in-memory string:

from simisa import s, t, w

shape_text = s.dumps(shape_obj)
terrain_text = t.dumps(terrain_obj)
world_text = w.dumps(world_obj)

Compressed

To write compressed text data to disk set the compressed parameter to True:

from simisa import s, t, w

s.dump(shape_obj, "path/to/shapefile.s", compressed=True)
t.dump(terrain_obj, "path/to/terrainfile.t", compressed=True)
w.dump(world_obj, "path/to/worldfile.w", compressed=True)

Binary

To write binary data to disk set the binary parameter to True:

from simisa import s, t, w

s.dump(shape_obj, "path/to/shapefile.s", binary=True)
t.dump(terrain_obj, "path/to/terrainfile.t", binary=True)
w.dump(world_obj, "path/to/worldfile.w", binary=True)

And of course binary data may also be compressed:

from simisa import s, t, w

s.dump(shape_obj, "path/to/shapefile.s", binary=True, compressed=True)
t.dump(terrain_obj, "path/to/terrainfile.t", binary=True, compressed=True)
w.dump(world_obj, "path/to/worldfile.w", binary=True, compressed=True)

Accessing the object trees

All data can be accessed on the returned object after using the .load() and .loads().

from simisa import shape

shape_obj = shape.load("path/to/shapefile.s")

print(shape_obj)
print(len(shape_obj.points))
print(shape_obj.lod_controls[2].lod_dlevel)

Here's an example of traversing the object tree deeply to access vertex and triangle data in a shape:

>>> print(shape_obj)
Shape(shape_header=ShapeHeader(flags1=0, flags2=0), volumes (len=12), shader_names (len=2), texture_filter_names (len=2), points (len=3962), uv_points (len=1841), normals (len=2725), sort_vectors (len=11), colours (len=0), matrices (len=10), images (len=11), textures (len=15), light_materials (len=0), light_model_cfgs (len=1), vtx_states (len=12), prim_states (len=30), lod_controls (len=1), animations (len=1))
>>> print(len(shape_obj.points))
3962
>>> print(shape_obj.lod_controls[0].distance_levels[2])
DistanceLevel(distance_level_header=DistanceLevelHeader(dlevel_selection=800.0, hierarchy (len=10)), sub_objects (len=1))
>>> print(len(shape_obj.lod_controls[0].distance_levels[2].sub_objects[0].vertices))
133
>>> print(len(shape_obj.lod_controls[0].distance_levels[2].sub_objects[0].primitives[0].indexed_trilist.vertex_idxs))
67

Editing the object trees

The object tree can also be edited and written back to disk or an in-memory string.

from simisa import shape
from simisa.shape import UVPoint

shape_obj = shape.load("path/to/shapefile.s")

# Emptying the points list
shape_obj.points = []

# Adding a new UVPoint
new_uv_point = UVPoint(0.0, 1.0)
shape_obj.uv_points.append(new_uv_point)

# Write to disk
shape.dump(shape_obj, "path/to/shapefile_edited.s")

# Write to an in-memory string
edited_shape_str = shape.dumps(shape_obj)

Checking header data

This Python module also contains helper functions for probing the SIMISA header. Useful if you want to know the compression state, the file type, or the file version before actually reading it.

Compression

To check the compression state use is_compressed. This function returns True if compressed, False if not, and otherwise returns None if the file has no valid header or if the module is unable to determine the compression state.

import simisa

simisa.is_compressed("path/to/shapefile.s")

Reading file type and version

To read file type and version use read_filetype and read_fileversion. These functions return the file type and version respectively.

import simisa

simisa.read_filetype("path/to/shapefile.s")
simisa.read_fileversion("path/to/shapefile.s")

Checking file format

To determine file format use is_utf16le, is_text and is_binary. These functions return True or False depending on the format. They may also return None if the file has no valid header or if the module is unable to determine the format.

import simisa

simisa.is_utf16le("path/to/shapefile.s")
simisa.is_text("path/to/shapefile.s")
simisa.is_binary("path/to/shapefile.s")

Using progress callbacks

To track the progress of reading and writing files, you can provide a callback function to the progress parameter.

from simisa import s

def print_progress(message, fraction):
    print(f"Progress: {fraction * 100:.1f}% - {message}")

shape_obj = s.load("/path/to/shapefile.s", progress=print_progress)

Or as a lambda:

from simisa import s

print_progress = lambda m, f: print(f"Progress: {f * 100:.1f}% - {m}")

shape_obj = s.load("/path/to/shapefile.s", progress=print_progress)

Enabling verbose logging

To enable verbose logging use the logging module. You can use either logging.INFO or logging.DEBUG depending on how much detail is needed. The latter provides everything, including all STF tokens, blocks, and values read.

Here's an example of enabling the logging.DEBUG log level:

import logging
from simisa import s

logging.basicConfig(level=logging.DEBUG)

shape_obj = s.load("/path/to/shapefile.s", verbose=logging.DEBUG)

To write the output to a file you can instead use basicConfig as follows:

logging.basicConfig(
    filename="output.log",
    level=logging.DEBUG,
)

Running Tests

You can run tests manually or use tox to test across multiple Python versions.

Run Tests Manually

First, install the required dependencies:

pip install pytest

Then, run tests with:

pytest

Run Tests with tox

First, install the required dependencies:

pip install tox pytest

Then, run tests with:

tox

This will execute tests for all Python versions specified in tox.ini.

Contributing

Contributions of all kinds are welcome. These could be suggestions, issues, bug fixes, documentation improvements, or new features.

For more details see the contribution guidelines.

License

The source code of this project is licensed under the GNU General Public License v3.0 (GPL-3.0). You are free to use, modify, and distribute the code under the terms of this license.

See the LICENSE file for the full license text.