danzimmerman

Quaternion Notes and Cheatsheet

Basics

Following [1], which has further useful information.

A quaternion is defined in terms of its scalar part $w$ and vector part $\mathbf{v}$:

$\huge\mathbf{q} = (w,\hspace{0.5em}\mathbf{v}) = (w, x, y, z)$

danzimmerman

#Following https://gist.github.com/EricCousineau-TRI/b713101b2a90d16e230fc250077ec4a2 (which is used to avoid clashing with Drake)

# In terminal: Install
bash ~/Downloads/Mambaforge-<whatever platform>.sh -b -s -p ~/.local/opt/mambaforge
ln -s ~/.local/opt/mambaforge/bin/conda ~/.local/bin

# Add to ~/.bash_aliases:
# Add function to explicitly add in conda shell util, rather than using its injected defaults.
conda-setup() {
    eval "$(conda shell.bash hook)"

danzimmerman

class DaeMeshFileSetObject(object):
    def __init__(self, dae_file, meshcat_path_string):
        """
        Assumes that all images are in the same directory as the .dae file
        """
        self.file = pathlib.Path(dae_file).absolute().resolve()
        self.path = meshcat_path_string
        # -- we don't really need to hold on to these but for debugging it'll be nice to keep them
        self.dae_tree = None
        self.file_contents = None

danzimmerman

import base64
import pathlib
import xml.etree.ElementTree as Et
import uuid 

class DaeMeshFileSetObject(object):
    def __init__(self, dae_file, meshcat_path_string):
        """
        Assumes that all images are in the same directory as the .dae file
        """

danzimmerman

<?xml version="1.0" ?>
<!-- =================================================================================== -->
<!-- |    This document was autogenerated by xacro from C:\Code\ros\workspaces\noethp_ws\src\universal_robot\ur_description\urdf\ur.xacro | -->
<!-- |    EDITING THIS FILE BY HAND IS NOT RECOMMENDED                                 | -->
<!-- =================================================================================== -->
<robot name="ur">
  <!--
    Base UR robot series xacro macro.

    NOTE: this is NOT a URDF. It cannot directly be loaded by consumers

danzimmerman

# advance matplotlib property cycler on the axis ax 5 lines
N = 5
for n in range(0, N):
  ax._get_lines.prop_cycler.__next__()

danzimmerman

{
  "configurations": [
    {
      "browse": {
        "databaseFilename": "",
        "limitSymbolsToIncludedHeaders": true
      },
      "includePath": [
        "C:\\Code\\ros\\workspaces\\npe_ws\\devel\\include\\**",
        "C:\\opt\\ros\\melodic\\x64\\include\\**",

danzimmerman

I'm using the BOOST_DLL_ALIAS / boost_import_alias() machinery following this recipe to load a DLL library I developed in C++. It's been working great for me.

The library functionality is all in a single class Foo. There's a factory method Foo::Create() that returns a boost::shared_ptr to a new Foo, and a single BOOST_DLL_ALIAS in the project that exports Foo::Create() to a DLL symbol CreateFoo. The project is compiled to FooLibrary.dll and can be loaded and used from C++ exactly as described in the docs.

I want to be able to access the functionality from Python as well, so I defined a pybind11 interface using the PYBIND11_MODULE macro. The module's __init__ is bound to Foo::Create() though I've also tried it bound to a different factory function with the same results. When I compile with the pybind interface, I can

danzimmerman

# Key bindings, up/down arrow searches through history
# From https://unix.stackexchange.com/questions/5366/command-line-completion-from-command-history
"\e[A": history-search-backward
"\e[B": history-search-forward
"\eOA": history-search-backward
"\eOB": history-search-forward

danzimmerman

DOES NOT WORK!!! Windows 10 Instructions - PyNEC From Source in Anaconda 3 virtual environment with WSL2 + Ubuntu + VS2019

First of all, you need to follow the original installation instructions for PyNEC with respect to things you need to install on your computer.

This includes installing swig and C/C++ compilers. I have Visual Studio 2019 Community Edition installed, which gives me the MSVC compiler tools. I installed swig 4.0.2 and added it to my PATH.

When I tried the rest of the instructions, I couldn't get build.sh to work. Presumably I need to install make for Windows to get this to work? I think I also had trouble with the softlink. Will try again later with git bash trying to apply some of the things I learned here. However, I got it installed using the instructions below.

These modified instructions use Windows Subsystem for Linux for the make and configure steps, and