imstk-unity Documentation

Release 0.1.0

Kitware

Jun 09, 2022

User Guide

1 Introduction 1 1.1 Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 1.2 Project Structure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

2 Setup for Development 3

3 Devices 4 3.1 Debugging . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

4 Usage 4 4.1 Importers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 4.2 SimulationManager . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 4.3 iMSTKBehaviour . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 4.4 GeometryFilter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 4.5 Editor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

5 Releases 5

6 Apache License 5 6.1 TERMS AND CONDITIONS FOR USE, REPRODUCTION, AND DISTRIBUTION . . . . . . . . 5 6.2 1. Definitions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 6.3 2. Grant of Copyright License. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 6.4 3. Grant of Patent License. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 6.5 4. Redistribution. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 6.6 5. Submission of Contributions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 6.7 6. Trademarks. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 6.8 7. Disclaimer of Warranty. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 6.9 8. Limitation of Liability. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 6.10 9. Accepting Warranty or Additional Liability. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 6.11 APPENDIX: How to apply the Apache License to your work . . . . . . . . . . . . . . . . . . . . . . 8

7 Contact 8 iMSTK is a free & open source C++ toolkit for prototyping of interactive multi-modal surgical simulations. The iMSTK-Unity asset gives you access to its’ capabilities through the Unity authoring interface. While this asset is still under development you can already exercise a variety of parts of iMSTK inside of Unity. This guide will help you get acquainted with the architecture and workings of the plugin.

iMSTK-Unity

User Documentation

1 Introduction

This document describes the iMSTK-Unity interface as well as how to build and develop it.

1.1 Overview

iMSTK is a free & open source C++ toolkit for prototyping of interactive multi-modal surgical simulations. The iMSTK-Unity asset provides classes that allow the use of iMSTK features inside of unity, those are amongst others various rigid and deformable models, collision detection and response, geometric importers and filters.

The iMSTK-Unity classes utilizes a C# interface of iMSTK that is generated by using the SWIG tool. This interface in effect is wrapped around most C++ functions and forwards its call to the original C++ code. This allows you to use iMSTK in C# much the almost the same way as you would in C++.

The best way to reach us is by using the issue tracker

1.2 Project Structure

The files of the asset are split in the following directories:

• iMSTK/Scripts: This directory is for the runtime scripts of the plugin.

• iMSTK/Scripts/Editor: This directory is for the editor scripts of the plugin. These scripts implement custom editor functionality. Editor scripts may use runtime scripts but won’t be included in the player, which means you should not use functions from these in your own scripts

• iMSTK/Resources: This directory contains resources required during runtime.

• iMSTK/Editor/Resources: This directory contains resources required in the editor (such as style sheets or UI markup).

• iMSTK/Plugins: This directory is for libraries (dlls/so) that Unity needs to load.

Directories needed for the project but not relevant to the plugin:

• iMSTK/Models, Materials, & Textures: These directories are for various assets used by the Demo. They are not part of the plugin.

3 The asset on the store may not contain the latest version of iMSTK-Unity, if you want to be up to date you can check out the sources from gitlab. As the binary files for iMSTK aren’t included in the repository, you will also have to build iMSTK yourself when you go this route.

2 Setup for Development

When checking out iMSTK-Unity from gitlab you will first need to build iMSTK. iMSTK uses CMake for its build system. iMSTK is a superbuild meaning it builds, includes, and links to all of its dependencies. There is no need to go find them. To build iMSTK clone the iMSTK repository and build it using cmake. Turn on the IMSTK_BUILD_FOR_UNITY cmake switch. This will reduce the number of dependencies that are being built. It will also enable the generation of “.cs” files as well as “.dlls”/”.so” files in your install directory that are needed by the “.cs” code. These will be used in Unity. Optionally enable iMSTK_USE_VRPN and/or iMSTK_USE_OpenHaptics for device support.

You can install the binaries two different ways, for both methods you need to know the directory in which iMSTK was installed. If you didn’t change anything that directory will be called install and resides inside the directory that you defined in cmake to build imstk, e.g. C:Projectsimstkbuildinstall :

• Using �InstallImstk.bat� from the asset directory the format is

InstallImstk.bat <path to imstk/install>

• Alternatively you can enable Developer Mode for iMSTK inside of Unity. This option ca be found in “Edit- >Project Settings->iMSTK Settings”. When turned on, you will prompted to install iMSTK whenever you start Unity. After turned on you may restart Unity, when it prompts you, select yes and provide it your iMSTK install directory, located in <iMSTK build directory>/install. All the necessary files will be copied. If you don’t want to be asked to reinstall iMSTK toggle this option off again.

If you make changes in iMSTK you must reinstall it to Unity.

Note: There is a ‘Force Install’ button to install iMSTK into Unity at the instant it is clicked. This may no always work depending on if an iMSTK script (that utilizes a given dll) has run in the editor. In that case those dll’s cannot be unloaded from Unity.

Note: Make sure Unity is not running. Sometimes it can close but still be running in the background prevent installation.

3 Devices

The asset available from the asset store does not have OpenHaptics or VRPN enabled, to use external devices you will have to build iMSTK for yourself. After enabling enable iMSTK_USE_VRPN or iMSTK_USE_OpenHaptics respectively. This will create a version of iMSTK with device support enabled. When the build is done install iMSTK into the Unity Asset as described above.

3.1 Debugging

Debugging may be done in visual studios, even on the native side. You must attached the debugger as you would to an external process. With iMSTK open in visual studios, click debug->attach to process. Select the unity executable and make sure you’re set on native debugging.

4 Usage

For minimal usage of iMSTK-Unity, two things must be added to a Unity Scene.

• A GameObject with a SimulationManager attached to it

• A GameObject with a Model attached to it.

Commonly a PhysicsGeometry is also needed on the Model GameObject.

4.1 Importers

iMSTK-Unity provides a custom Unity importer to import geometry using iMSTK. This may import point, line, surface, tetrahedral, & hexahedral meshes (vtk, vtu, stl, ply, veg, ...). If the mesh imported is a point, line, or surface mesh then it will be imported as a Unity Mesh object. Anything else not supported by Unity, is loaded as an iMSTKUnity Geometry Object. When a volumetric mesh (such as a tetrahedral mesh) is imported the accompanying surface is extracted and provided as an additional asset.

4.2 SimulationManager

SimulationManager is a component responsible for managing the simulation. There may only exist one. It also controls the construction, initialization, and destruction of iMSTKBehaviour’s to ensure execution ordering: Simulation Manager created -> iMSTK objects created and internally initialized -> iMSTK objects externally initialized -> SimulationManager Start -> Updates -> iMSTK objects cleaned up -> SimulationManager cleaned up.

This component is required to be in the scene for simulations to run. It is created before any other iMSTK components on any GameObject. It implements the start, stop, pause, and other global scene related tasks.

4.3 iMSTKBehaviour

An extension of MonoBehaviour to provide different callbacks for special construction, initialization, and destruction ordering.

4.4 GeometryFilter

Similar to a MeshFilter in Unity. It provides an input and output geometry. It may take in any iMSTK geometry, as well as a Unity Mesh (one can also drag/drop a MeshFilter to it). These are instances of geometries used in all of iMSTK unity scripts.

4.5 Editor

iMSTK-Unity provides extensions to the Unity editor. These extensions include:

• Custom inspectors for the models and geometry components.

• A global settings menu.

• Menu Items for quick creation of GameObject with iMSTK items already setup.

• Editors/windows for various operations

5 Releases

TBD

6 Apache License

Version 2.0

Date January 2004

URL http://www.apache.org/licenses/

6.1 TERMS AND CONDITIONS FOR USE, REPRODUCTION, AND DISTRIBUTION

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END OF TERMS AND CONDITIONS

6.11 APPENDIX: How to apply the Apache License to your work

To apply the Apache License to your work, attach the following boilerplate notice, with the fields enclosed by brackets “[]” replaced with your own identifying information. (Don’t include the brackets!) The text should be enclosed in the appropriate comment syntax for the file format. We also recommend that a file or class name and description of purpose be included on the same “printed page” as the copyright notice for easier identification within third-party archives.

Copyright 2020 iMSTK-Unity

Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License. You may obtain a copy of the License at

http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License.

7 Contact

If you have any questions or feedback you reach out to us at the iMSTK Discourse Forum or the iMSTK-Unity Issue Tracker