This month in rustsim #5 (March 2019)

Welcome to the fifth edition of This month in rustsim. This monthly newsletter will provide you with a summary of important update that occurred within the rustsim community. This includes in particular updates about the nphysics, ncollide, nalgebra, and alga crate.

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Progress of current developments

Complex numbers support for alga 0.9 and nalgebra 0.18

The most notable progress this month is the addition of full support of complex numbers in alga and nalgebra. This was one of our big goals for 2019! This implies:

  • The addition of a new trait alga::general::ComplexField which is implemented by num_complex::Complex and floats like f32 and f64.
  • The rename of the alga::general::Real trait to RealField for uniformity. This trait derives from ComplexField.
  • The use of ComplexField instead of RealField whenever it makes sense mathematically. Complex numbers are still forbidden as parameters of transformation types (like Isometry3, Quaternion, Similarity, etc.) from the geometry module.

This last point implies that all matrix decomposition algorithms support complex matrices as well. This was a non-straightforward work as the algorithms had to be adapted to work on both complex and real matrices with the same generic code. This also implied adding implementation BLAS operations like gerc and dotc that take the adjoint of one of its inputs. Refer to nalgebra's CHANGELOG for a complete list of methods added to the version 0.18.

Finally, keep in mind that all this remain compatible with #[no-std].

Other additions to nalgebra

  1. A significant amount of work has been delivered by adamnemecek to add the implementation of trigonometric function on quaternions, as well as some geometric algebra operators. In the continuity of this work, we are in the process of discussing the addition of dual-quaternions (which can represent a transformation like an isometry) to nalgebra.
  2. A first implementation of convolution has been added to nalgebra by npapapietro. This implementation is not based on a FFT yet though that would be a great addition for anyone interested!

Next objectives

Our next goal has already been mentioned before, and this time we will start working on it for good: the addition of Continuous Collision Detection (CCD) to nphysics! This will prevent fast-moving objects from passing through other objects (also known as the "tunneling effect".) We expect this work to take at least two months with the following best-case scenario:

  1. April will be dedicated to experimenting various designs as we want modifications made for CCD to prepare the road for the future addition of multithreading.
  2. May will be dedicated to actually implementing whatever design we selected.


We would like to thank the whole community and contributors. In particular, thanks to the contributors from the past month1:

Finally, thanks to all the former, current and new patrons supporting sebcrozet, the lead developer of the current crates part of this organization on patreon! This help is greatly appreciated and allows me do spend a significant amount of time developing those crates.

  1. The list of contributors is automatically generated from past month's github commit history. Don't hesitate to let us know if your name should have been mentioned here.