xpppq / easy3d

A lightweight, easy-to-use, and efficient C++ library for processing and rendering 3D data

Easy3D is an open-source library for 3D modeling, geometry processing, and rendering. It is implemented in C++ and designed with an emphasis on simplicity and efficiency.

Easy3D is intended for research and educational purposes, but it is also a good starting point for developing sophisticated 3D applications.

Key features

• Efficient data structures for representing and managing 3D models such as point clouds, polygonal surfaces (e.g., triangle meshes), polyhedral volumes (e.g., tetrahedral meshes), and graphs. Easy to add/access arbitrary types of per-element properties. Non-manifoldness is automatically resolved when loading models from files ...

• A set of widely used algorithms, e.g., point cloud normal estimation/re-orientation, Poisson surface reconstruction, RANSAC, mesh simplification, subdivision, smoothing, parameterization, remeshing, and more (the implementation of several surface mesh processing algorithms were taken from PMP).

• A bunch of rendering techniques, e.g., point/line imposters, ambient occlusion (SSAO), hard shadow (shadow maps), soft shadow (PCSS), eye-dome lighting (for rendering point clouds without normal information), transparency (average color blending, dual depth peeling), and more.

• High-level encapsulation of OpenGL and GLSL for convenient and efficient rendering (based on modern and faster programmable-shader-style rendering, i.e., no fixed function calls). Client code does not need to touch the low-level APIs of OpenGL.

• Step-by-step tutorials demonstrating various uses of the API, to get acquainted with the data structures, rendering techniques, and algorithms for 3D modeling and geometry processing.

• Very easy to use as a callable library (usually only a few lines of code).

• A viewer that can be used directly to visualize 3D scenes in various formats, which can also be easily extended.

• A handy tool Mapple created out of the Easy3D library for rendering and processing 3D data.

Scalar field	Polyhedral mesh	Keyframe animation

A quick glance

Any types of 3D drawables (e.g., points, lines, triangles, and thus point clouds, mesh surfaces, scalar fields, vector fields) can be rendered by writing a few lines of code with Easy3D. For example, the following code renders a point cloud as a set of spheres

// assume your point cloud has been loaded to the viewer
PointsDrawable* drawable = cloud->renderer()->get_points_drawable("vertices");
drawable->set_impostor_type(PointsDrawable::SPHERE); // draw points as spheres.
drawable->set_point_size(3.0f);    // set point size

or as a set of surfels (i.e., 3D discs)

drawable->set_impostor_type(PointsDrawable::SURFEL);

By abstracting geometric elements as one of the above drawables, more general visualization (e.g., vector fields, scalar fields) can be done very conveniently.

Easy3D repository layout

The repository contains a CMakeLists.txt file (in the root directory of the repository) that serves as anchor for configuring and building programs, and a set of subfolders:

• 3rd_party - source code of third party libraries
• applications - applications built on top of Easy3D
• cmake - CMake-related configuration files
• docs - documentation configuration file (Doxygen)
• easy3d - source code of Easy3D
• resources - test data, images, shaders, and textures, etc.
• tests - a collection of test cases
• tutorials - a collection of examples (with detailed explanations in code)

Build Easy3D

Like most software, Easy3D depends on some third-party libraries. Easy3D has made this easier for the users by including the source code of most third-party libraries (for the core functionalities and the basic viewer), and it leaves very few optional (for a few additional features that are typically not needed by most users).

The optional third-party libraries are:

• CGAL (optional): Easy3D has implemented a few algorithms for advanced surface mesh processing, such as surface reorientation, detecting/resolving duplicate vertices/faces and self-intersection, and clipping/splitting/slicing surface meshes. These features are disabled by default (because most users don't need them). To enable these features, you can switch on the CMake option EASY3D_ENABLE_CGAL and make sure CGAL (v5.1 or later) is installed and visible to CMake. In case you have multiple versions of CGAL on your platform, simply provide the path of a suitable one to the CMake variable CGAL_DIR.

• Qt (optional): Easy3D supports Qt (v5.6 or later) for UI creation, which can help develop sophisticated applications for 3D data processing and visualization. The Qt support is disabled by default (because most users don't need it). You can switch on the CMake option EASY3D_ENABLE_QT to include the examples and applications that depend on Qt (e.g., Tutorial_202_Viewer_Qt and Mapple).

To build Easy3D, you need CMake (>= 3.12) and, of course, a compiler that supports >= C++11.

Easy3D has been tested on macOS (Xcode >= 8), Windows (MSVC >=2015), and Linux (GCC >= 4.8, Clang >= 3.3). Machines nowadays typically provide higher supports, so you should be able to build Easy3D on almost all platforms.

There are many options to build Easy3D. Choose one of the following (or whatever you are familiar with):

• Option 1: Use CMake to generate Makefiles and then make (on Linux/macOS) or nmake(on Windows with Microsoft Visual Studio). For example, on Linux or macOS, you can simply

  $ cd Easy3D
  $ mkdir Release
  $ cd Release
  $ cmake -DCMAKE_BUILD_TYPE=Release ..
  $ make
  

• Option 2: Use any IDE that can directly handle CMakeLists files to open the CMakeLists.txt in the root directory of Easy3D. Then you should have obtained a usable project and just build it. I recommend using CLion or QtCreator.

• Option 3: Use CMake to generate project files for your IDE. Then load the project to your IDE and build.

Don't have any experience with C/C++ programming? Have a look at How to build Easy3D step by step.

Test Easy3D

A test suite is provided in the tests subfolder, which contains a collection of automated test cases (for data structures, IO, algorithms, visualization, etc.) and some semi-automated test cases (for GUI-related functionalities that require interactive user input). All cases are integrated into a single target tests.

To build and run the test suite, download the entire source, use the CMakeLists.txt in the root directory of the repository, switch on the CMake option EASY3D_BUILD_TESTS (which is disabled by default), and run CMake. After CMake, you can build ALL or only the tests target. Finally, run the tests executable (i.e., YOUR_BUILD_DIRECTORY/bin/tests) for the test.

Use Easy3D in your project

This is quite easy, maybe easier than many other open-source libraries :-) You only need to add the following lines to your CMakeLists file (don't forget to replace YOUR_APP_NAME with the actual name of your application) and point Easy3D_DIR to your build directory of Easy3D when doing cmake. Then the requested Easy3D libraries, include directories, and relevant compile definitions of Easy3D are visible and accessible to your project.

set(CMAKE_CXX_STANDARD 11)                        # specify C++ standard
find_package(Easy3D REQUIRED)                     # request Easy3D 
target_link_libraries(YOUR_APP_NAME easy3d::core) # request necessary Easy3D modules (add more if needed, e.g., viewer, algo)

The minimum code to have a 3D viewer:

#include <easy3d/viewer/viewer.h>

int main(int argc, char** argv) {
    easy3d::Viewer viewer("Test");
    return viewer.run();
}

Documentation

The documentation for Easy3D-v2.4.4 is available here.

The Easy3D Documentation is an ongoing effort with more and more details being added. You can build the latest Easy3D documentation from the source code. Easy3D uses Doxygen (>= 1.8.3) to generate documentation from source code. To build it from the source code, install Doxygen first. Then, switch on the CMake option EASY3D_BUILD_DOCUMENTATION in the main CMakeList.txt. Finally, build the doc target to generate the documentation.

Questions, new features, bugs, or contributing to Easy3D

See the Contribution Guide for more information.

License

Easy3D is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 3 of the License or (at your option) any later version. The full text of the license can be found in the accompanying 'License' file.

Acknowledgments

The implementation of Easy3D greatly benefited from and was inspired by existing great open-source libraries, such as PMP, libQGLViewer, Surface mesh, and Graphite. In particular, the implementation of several surface mesh algorithms was taken (with modifications) from PMP, i.e., simplification, subdivision, smoothing, parameterization, remeshing, hole filling, geodesic distances, fairing, curvatures, and triangulation. We would like to thank the original authors of these projects for their permissive license terms. We also thank the users and contributors for reporting/fixing bugs, testing, and providing valuable feedback and suggestions.

Citation

If you use Easy3D in a scientific work, I kindly ask you to cite it:

@article{easy3d2021,
  title = {Easy3{D}: a lightweight, easy-to-use, and efficient {C}++ library for processing and rendering 3{D} data},
  author = {Liangliang Nan},
  journal = {Journal of Open Source Software}，
  year = {2021},
  volume = {6},
  number = {64},
  pages = {3255},
  doi = {10.21105/joss.03255},
  url = {https://doi.org/10.21105/joss.03255}
}

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Should you have any questions, comments, or suggestions, please contact me at [email protected]

Liangliang Nan

Dec. 8, 2018