impasse 5.0.1

Alternate Python bindings for the Open Asset Import Library (ASSIMP)

Impasse Readme

A simple Python wrapper for Assimp using cffi to access the library. Requires Python >= 3.8.

It's largely based on PyAssimp, Assimp's official Python port. In contrast to PyAssimp, it strictly targets modern Python 3 and provides type hints. It also aims to allow mutating scenes before exporting by having all wrapper classes operate directly on the underlying C data structures.

Note that impasse is not complete. Many ASSIMP features are missing.

USAGE

Complete example: 3D viewer

impasse comes with a simple 3D viewer that shows how to load and display a 3D model using a shader-based OpenGL pipeline.

To use it:

$ cd scripts
$ python ./3d_viewer_py3.py <path to your model>

You can use this code as starting point in your applications.

Writing your own code

To get started with impasse, examine the simpler sample.py script in scripts/, which illustrates the basic usage. All Assimp data structures are wrapped using ctypes. All the data+length fields in Assimp's data structures (such as aiMesh::mNumVertices, aiMesh::mVertices) are replaced by simple python lists, so you can call len() on them to get their respective size and access members using [].

For example, to load a file named hello.3ds and print the first vertex of the first mesh, you would do (proper error handling substituted by assertions ...):

from impasse import load
with load('hello.3ds') as scene:

  assert len(scene.meshes)
  mesh = scene.meshes[0]

  assert len(mesh.vertices)
  print(mesh.vertices[0])

Another example to list the 'top nodes' in a scene:

from impasse import load
with load('hello.3ds') as scene:

  for c in scene.root_node.children:
      print(str(c))

INSTALL

Install impasse by running:

$ pip install -e .

Impasse requires an assimp dynamic library (DLL on Windows, .so on linux, .dynlib on macOS) in order to work. The default search directories are:

• the current directory
• on linux additionally: /usr/lib, /usr/local/lib, /usr/lib/x86_64-linux-gnu

To build that library, refer to the Assimp master INSTALL instructions. To look in more places, edit ./impasse/helper.py. There's an additional_dirs list waiting for your entries.