Revision as of 01:50, 8 November 2014 by Inderpreet (talk | contribs) (Code)

This is a list of succinct tasks that are expected to take most people familiar with the prerequisites less than two hours to complete. It's a great starting point for anyone interested in contributing to BRL-CAD.

The tasks are all roughly the same complexity with no prior BRL-CAD experience expected. A description is provided along with a list of references and files you'll probably need to edit. Can we make it any easier?

Getting Started

Contact us (via IRC or brlcad-devel mailing list) if you have questions, comments, or ideas of your own you'd like to suggest.

We've made an awesome virtual disk image that has everything you need preconfigured and ready to go:

  1. Download our BRL-CAD Virtual Machine (VM) disk image.
  2. Install VirtualBox.
  3. Import and start the VM, log in (the password is "Brlcad!" without the quotes).
  4. Run "svn up brlcad-svn-trunk" and get started!

Pick a Task

We break down all tasks into one of five categories. Don't be worried if the tasks all sound confusing to you. Just pick one and start reading the references we've provided. Join IRC or our mailing list and ask questions.

  1. Code (programming)
  2. Documentation and Training (writing)
  3. Outreach and Research (graphics)
  4. Quality Assurance (testing)
  5. User Interface (designing)



Tasks related to writing or refactoring code

See the When You're Done section above for details on submitting your changes.


Fix bounding box function for our polygonal mesh (BoT) primitive

BRL-CAD provides functions for its geometric primitives that define a bounding box - a box that completely encloses the volume described by the primitive. Ideally, these boxes are as small as possible while still enclosing the primitive. Currently the routine for BoTs is incorrect. You can use stl-g, obj-g, or any of our other *-g converters to import BoT geometry for testing.

This task involves studying the current code for the function rt_bot_bbox() and determining what is causing the current inaccuracies (the mged 'bb' command is a good way to visualize primitive bounding boxes). Make changes to produce a more optimal bounding box. Reimplement it from scratch if you like. The raytracing prep code in rt_bot_prep does prepare a better bounding box, so that is one place to check.


  • src/librt/primitives/bot/bot.c


Close MGED when both windows are closed

BRL-CAD has an interactive geometry editor called MGED. It's often the starting point for beginners and allows creation and manipulation of models using commands. When mged is run, it creates 2 windows: a text-console command window and an interactive graphics window. When the user closes one of those windows, there is a bug. Closing the graphics window closes the command window.

This task involves fixing this behavior so that ONLY closing both windows terminates the process properly and that closing either window does not take the other along with it.


  • src/mged/mged.c
  • src/tclscripts/mged/openw.c



Implement a primitive centroid function

BRL-CAD provides more than two dozen types of geometry "primitives" such as ellipsoids, boxes, and cones. Every primitive is described by a collection of callback functions, for example rt_ell_bbox() returns the bounding box dimensions for an ellipsoid. Wikipedia, Wolfram Mathworld, and various other math sites (and research papers) around the web include the equations for most of our basic primitives while others are a little more tricky to compute.

This task involves writing a new callback function that takes an rt_db_internal object and calculates its centroid (as a point_t 3D point). There are numerous examples in our code where we compute centroids for other primtiives. The primitives that do not already have a centroid callback are itemized in following.



  • src/librt/primitives/table.c
  • src/librt/primitives/[PRIMITIVE]/[PRIMITIVE].c

... centroid function for extruded sketches (EXTRUDE)


Implement a primitive UV-mapping callback

BRL-CAD provides more than two dozen types of geometry "primitives" such as ellipsoids, boxes, and cones. Every primitive is described by a collection of callback functions, for example rt_ell_bbox() returns the bounding box dimensions for an ellipsoid. One of those functions describes a UV mapping of the object's surface, which is used for things like texture and bump mapping. An example of this is rt_ell_uv() in the src/librt/primitives/ell/ell.c source file for an ellipsoid. Several of our more complex primitive types (such as BoT, NMG, and BREP/NURBS) do not presently implement a UV-mapping function leading to unexpected runtime behavior.

This task involves implementing a UV-mapping callback for any of the primitives that do not already have a functional UV-callback defined. Note that this is an advanced task that might take you more than a couple hours if you don't have solid coding skills, but it's ultimately just a few lines of code. See other primitives that already implement a UV-mapping callback for reference.


... UV-mapping for extruded sketches (EXTRUDE)


  • src/librt/primitives/extrude/extrude.c
  • src/librt/primitives/table.c
  • include/rtgeom.h



Implement a platform independent re-entrant sort function

The classic C library qsort() does not support a context parameter. A work around is to store the context information in a static variable. However, this solution is not thread save and may result in unpredictable behavior.

There are platform specific sort functions qsort_r() in incompatible versions for BSD and GNU and qsort_s() for MSVC. Your task is to implement a bu_sort() function for BRL-CAD which is platform independent.


  • src/libbu/sort.c

The new sort function could look like this:

void bu_sort(genptr_t array, size_t nummemb, size_t sizememb, int (*compare)(const_genptr_t, const_genptr_t, genptr_t), genptr_t context);


Solve fonts related bug in new wiki theme

BRL-CAD has been working on a new incarnation of the website and has developed a new wiki theme and wordpress theme. Wiki theme uses a font called 'open-sans' from google fonts directory. It's linked via CSS but it does not get loaded (we still see default serif all over the place). So your task will be to debug the CSS code and get Open Sans loaded.



Documentation and Training

Tasks related to creating/editing documents and helping others learn more about BRL-CAD

Add missing documentation (for any ONE command)

BRL-CAD is an extensive system with more than 400 commands and more than a million pages of documentation, but there are approximately 120 commands that are entirely undocumented:

a-d archer asc2g asc2pix bot-bldxf bottest brep_cube brep_simple brickwall btclsh burst bw-a bw-d bwish c-d chan_add clutter contours d-a damdf dauto dauto2 d-bw dconv ddisp d-f dfft d-i dmod double-asc dpeak dsel dsp_add dstat d-u dwin euclid_format euclid_unformat fbgammamod f-d fence fhor f-i g-adrt g-euclid1 g-jack globe g-off i-a i-d i-f ihist imod istat jack-g kurt lowp molecule nmgmodel nmg-sgp off-g pipe pipetest pix2g pix3filter pixcount pixelswap pixembed pixfields pixfieldsep pixflip-fb pixpaste pix-spm pix-yuv plstat pyramid rawbot remapid rlesortmap rletovcr room rtcell rtexample rtfrac rtrad rtsil rtsrv script-tab sketch solshoot sphflake spltest spm-fb ssampview syn tea tea_nmg testfree texturescale torii ttcp tube txyz-pl u-a u-bw u-d u-f umod ustat vcrtorle vegitation wall wdb_example xbmtorle xyz-pl yuv-pix

This task involves writing basic documentation for JUST ONE of those commands in the Docbook XML format. The command documentation should provide a one-sentence description, a detailed paragraph description (200+ words), explanation of all available command-line options, and one or more examples on how to use the command.


  • doc/docbook/system/man1/en/
  • doc/docbook/system/man1/en/*.xml


Write an article "BRL-CAD for dummies"

Although BRL-CAD has extensive documentation, still it needs a short and simple document which is particularly built for dummies.

This task involves writing a article named BRL-CAD for dummies. This article should start with the installation process, if there is any existing installation guide for dummies, provide a link to it. The main motive of this article to empower dummy to make his/her first model using BRL-CAD. One thing to be kept in mind while writing this article is that this article is mainly concentrated for dummies. So use simple language to an extent and if you need to mention some technical term, first explain that term.

The output of this task can be a pdf, html, doc, odt or any other document file that contains this article. Go through the link provided. Use screenshots and images to make it look attractive so that the reader is not bored.



Write a "BRL-CAD Commands Quick Reference" document

There is already a command quick reference for BRL-CAD's MGED geometry editing tool, but there is not a similar document for BRL-CAD's 400+ command-line commands.

This task involves writing a quick reference document similar to the MGED quick reference but for BRL-CAD commands. The sheet should minimally include the following commands:

mged, rt*, *-g, g-*, fb*, *fb, nirt, remrt, rtsrv, asc2g, g2asc, dbupgrade, pix*, *pix, *-*, brlman, benchmark



Doxygen cleanup

BRL-CAD uses Doxygen for most API documentation but the comment blocks are not optimally set up for Doxygen output.

This task involves cleaning up the Doxygen comments in the library so that useful reports and API documentation automatically generated (correctly, completely, and cleanly). Verify/fix any Doxygen syntax. Verify/fix groups so that functions are organized neatly and all contained within a group. Provide patches that give clean (PDF) output from Doxygen.


... doxygen cleanup for LIBBU

There are approximately 300 documented API function calls in LIBBU.


  • include/bu.h
  • src/libbu
  • misc/Doxyfile


... doxygen cleanup for LIBWDB

There are approximately 100 documented API function calls in LIBWDB.


  • include/wdb.h
  • include/raytrace.h
  • src/libwdb
  • misc/Doxyfile


... doxygen cleanup for LIBRT

There are approximately 1000 documented API function calls in LIBRT.


  • include/raytrace.h
  • src/librt
  • src/librt/primitives
  • src/librt/comb
  • src/librt/binunif
  • misc/Doxyfile


Write up Wiki page tutorial on our Volumetric Primitive

BRL-CAD provides a couple dozen distinct primitives. Each primitive is defined by a set of parameters. Several of the more complex primitives have a wiki page describing them in more detail with an example on how to create them.

This task involves writing up a page on the VOL primitive. Figure out how to use it (see the "in" command), create an example input data set, and write up a wiki page on exactly what steps are needed similar to our other wiki pages:


Show how to create a VOL with at least two layers/slices. Include images like the other examples. Put the write-up at


Write a wiki tutorial on how to create a polygonal mesh (NMG) manually

BRL-CAD provides a couple dozen distinct primitives. Each primitive is defined by a set of parameters. Several of the more complex primitives have a wiki page describing them in more detail with an example on how to create them.

This task involves writing up a page on the NMG polygonal mesh primitive. Figure out how to use it (not a simple task, will require some trial and error), create an example input, and write up a wiki page on exactly what steps are needed similar to our other wiki pages:


Note the "facetize" command in mged will convert an existing object into NMG format. The get/put commands should help from there like the sketch tutorial.

Show how to create an NMG cube or wedge or similar simple shape. Include images like the other examples. Put the write-up at


Fix Image Formatting in BRL-CAD's DocBook Documentation (any ONE large document or 4 smaller documents)

The majority of BRL-CAD's documentation is defined as DocBook files, from which other formats (HTML, PDF, man page, etc.) can be generated. PDF files present a particular challenge, and have some very specific requirements to achieve "good" formatting.

BRL-CAD's DocBook files need to uniformly use a style of image inclusion that is aware of what "role" the image is supposed to serve. A "basic" image inclusion example looks like this:

     <imagedata align="center" fileref="../../lessons/en/images/img.png" format="PNG"/>
       Caption goes here.

This task involves switching image inclusions that use the above style to something like the following:

   <imageobject role="html">
     <imagedata align="center" fileref="../../books/en/images/img.png" format="PNG"/>
   <imageobject role="fo">
     <imagedata align="center" fileref="../../books/en/images/img.png" format="PNG"/>
       Caption goes here.

The "role" flag to imageobject provides the opportunity to specify different image formatting options when the output is HTML (role="html") or PDF (role="fo").

The captions should be preserved as above on mediaobjects that have them, but mediaobjects without a caption should also be converted and there is no need to add a caption in such cases.

Any patch that makes changes to the DocBook sources should result in a successful "make doc" build test. This won't generate PDF documents, but it will validate the XML files and produce HTML - remember that introducing breakage means the patch won't be accepted.

Remember, the tasks are simply to do the above conversion for all images in the file or files, not to introduce PDF specific formatting. Formatting fixes will be needed, but they are very much "case by case" and will take both additional time and a working Apache FOP installation, as well as knowledge of how to enable PDF generation. If all image inclusions have been converted successfully and a student is interested in actually fixing the formatting, please discuss it with us on IRC or the mailing list.


  • doc/docbook/books/en/BRL-CAD_Tutorial_Series-VolumeIII.xml


  • doc/docbook

Outreach and Research

Tasks related to community management, outreach/marketing, studying problems, and recommending solutions


Profile NURBS prep performance

BRL-CAD implements support for rendering of NURBS representation geometry. If you import a solid 3DM or STEP format model into BRL-CAD, it will import as BREP/NURBS geometry. Opening that geometry in BRL-CAD's MGED editor will tell you what objects are available and our 'rt' tool will raytrace it. When geometry is ray traced, it first goes through a "prep" phase and then it starts shooting rays. Our prep phase is entirely unoptimized so we'd like to know where all the time is presently being spent during prep..

This task involves importing some NURBS geometry into BRL-CAD and ray tracing that geometry with a profiler watching our prep performance. Any profiler will do, including gprof, but a performance monitor like oprofile or the Mac "Instruments" application (or Shark) are preferred.

Learning how to use a profiler is beyond the scope of this task, so it make take you considerably longer to provide us with useful information if you've never run a profiler before.

To capture prep performance, you will need to import some fairly complex geometry. You should be able to search google with "filetype:3dm" or "filetype:step" or find something on to import

Running "tops" within mged will tell you what geometry is available for rendering.

Running "rt -o file.png -s32" on the system command line (not inside mged) should minimize the ray overhead or you can specifically isolate the prep phase we care about. Prep is the time between when rt is run where it opens a window until the first pixels are fired and pixels start filling in.


Continue investigating GMP integration

BRL-CAD uses a fastf_t typedef for most all math operations that is usually a "double" floating point type. We would like to provide the option for resorting to exact arithmetic if possible by merely redefining fastf_t to a C++ type sufficiently overloaded to behave the same. You should be proficient with C++ operator overloading to take this work on. This task is a continuation of a prior GCI task (read it in full!):

This task involves testing compilation with a C++ class with overloaded operators such that vmath macro calls still work as well as a sampling of LIBBN API function calls without major changes to the original code. A perfect example case study would be creating the class then testing whether bn_dist_pt3_pt3() and bn_mat_determinant() compute correctly for values that cannot be exactly represented with floating point arithmetic.

Building on the previous GCI task work, take it to the next step. Try setting a vector to 1/3, 1/3, 1/3 and 0.1, 0.1, 0.1 and get proper values to print. Change the V3ARGS() macro if needed. If that all works, try to get bn_dist_pt3_pt3() to work. Report and discuss your progress.


Design a T-Shirt for BRL-CAD

This task involves designing a T-Shirt for BRL-CAD. Use your designing skills to design a T-Shirt for BRL-CAD. You can use the current BRL-CAD logo, or you may tweak it. Be creative while designing this T-Shirt. It would be good if the design has some special meaning.

Logo References


Design a coffee mug for BRL-CAD

This task involves designing a coffee mug for BRL-CAD. Make it look good, so that one can use it while working on BRL-CAD. Look over some great coffee mug designs before starting to work on this. It would be great if the design on coffee mug has some special meaning.

Logo References


Design BRL-CAD sticker

This task involves designing a BRL-CAD sticker. The design should be simple and sleek. The concept of sticker should be clear and also it should be creatively presented. Get inspired from some sticker designs but choose your own imagination while designing the sticker. There is no bound for shape of sticker, it can be rectangular, circular or even irregular. The only thing that matters is that it should look good.

Logo References


Design BRL-CAD phone/tablet back cover

This task involves designing a BRL-CAD phone/tablet cover. While submitting your design, provide the sample phone cover, tablet cover with the design and rendered png or jpg image of the sticker design. Try to have a special meaning of design, and the concept should be creatively illustrated.

Logo References


Design a wallpaper set for BRL-CAD

This task involves designing a set of wallpapers for BRL-CAD. The central idea of each wallpaper should represent any feature of BRL-CAD. Try to design a minimum of 5 wallpapers but if you have more than 5 designs than you are welcomed.

Try to different resolutions of each wallpaper.

Check the following wallpapers for inspiration.

Logo References


Create Iron Man Arc Reactor Model in BRL-CAD

This task involves creating Arc Reactor as seen in hollywood movie Iron-Man. You will have to create two versions of the Arc Reactor one glowing and another non glowing.

Check this model for inspiration

Quality Assurance

Tasks related to testing and ensuring code is of high quality

Fix single-precision floating point crash

By default, all of BRL-CAD compiles using double-precision floating point arithmetic. We provide a simple typedef, however, that converts almost the entire system over to single-precision floating point. This compilation mode was recently cleaned up and tested, but a bug was found. The problem is reproduced very simply by compiling in single precision mode and running our "rt" ray tracer tool.

To compile in single precision, edit the include/bn.h header file and change the fastf_t typedef from double to float. To reproduce the bug, compile BRL-CAD and write this out to a text file named star.view:

viewsize 2.500000000e+05;
eye_pt 2.102677960e+05 8.455500000e+04 2.934714650e+04;
viewrot -6.733560560e-01 6.130643360e-01 4.132114880e-01 0.000000000e+00
        5.539599410e-01 4.823888300e-02 8.311441420e-01 0.000000000e+00
        4.896120540e-01 7.885590550e-01 -3.720948210e-01 0.000000000e+00
        0.000000000e+00 0.000000000e+00 0.000000000e+00 1.000000000e+00 ;
start 0;

Then run rt feeding it that view script as input. This is an example how to run within the gdb debugger:

gdb path/to/bin/rt
(gdb) run -F/dev/X -M .cmake/share/db/star.g all < star.view

At this point, rt should crash due to an infinite recursion. A backtrace in the debugger will show lots and lots of calls to rt_shootray() and light_hit().

This task involves investigating and preventing the crash. Provide a patch that fixes the bug.


  • man gdb
  • brlman rt


  • src/librt/shoot.c
  • src/liboptical/sh_light.c


Fix closedb

BRL-CAD geometry editor application (mged) has several hundred commands including two very simple commands for opening and closing a geometry database file. While the user rarely ever needs to close the file, as all changes are always immediately saved, it can be of use to scripting applications. However, at some point in the recent past, the closedb command was horked. It's undoubtedly something very simple but we haven't bothered to look due to other priorities. You can fix it. If you run these simple steps within graphical mged, you should see how commands stop working after calling closedb:

 mged> opendb test.g y
 mged> make sph sph
 mged> l sph
 mged> closedb
 mged> make sph sph
 mged> opendb test.g
 mged> l sph
 mged> exit

Provide a patch that fixes the bug or tell us which SVN revision introduced the bug. Make sure you can reproduce the bug before claiming this task, which presumes you know how to download/install BRL-CAD from a source distribution.


  • src/mged/mged.c


Create an utility library (LIBBU) API unit test

There are more than 300 library functions in our core LIBBU library. As a core library used by nearly every one of BRL-CAD's tools, testing those functions for correct behavior is important.

This task involves implementing a new unit test for any of LIBBU's source files that do not already have a unit test defined. The test should run all of the public functions and be hooked into our build system. We have lots of existing unit tests to follow as an example.


  • include/bu.h
  • src/libbu/*.c
  • src/libbu/tests/*.c


  • src/libbu/tests/[TEST].c
  • src/libbu/tests/CMakeLists.txt

... unit test for LIBBU bomb.c


Create numerics library (LIBBN) API unit test

There are more than 300 library functions in our core LIBBN library. As a core library used by nearly every one of BRL-CAD's tools, testing those functions for correct behavior is important.

This task involves implementing a new unit test for any of LIBBN's source files that do not already have a unit test defined. The test should run all of the public functions and be hooked into our build system. We have lots of existing unit tests to follow as an example.


  • include/bn.h
  • include/plot3.h
  • include/vmath.h
  • src/libbn/*.c
  • src/libbu/tests/*.c <-- note libbu, not libbn for examples


  • src/libbn/tests/[TEST].c
  • src/libbn/tests/CMakeLists.txt

... unit test for LIBBN axis.c


... unit test for LIBBN qmath.c


... unit test for LIBBN rand.c


Find, reliably reproduce, and report any bug in Archer

Archer is our new modeling interface and a soon to merge with our long-standing MGED geometry editor. It undoubtedly has bugs. It's your job to find one, but do so in a manner that is so obvious that one of the other devs will be able to instantly reproduce the bug given your specific instructions. Find a way to make archer crash, become unresponsive, or otherwise behave incorrectly. You will have to explore the tool with minimal documentation.

This task involves filing a bug report with verifiable and reproducible steps that clearly demonstrate the bug. It can't be a bug already reported or otherwise documented nor can it be merely behavior you don't like.



Reproduce any 10 unconfirmed open bug reports

BRL-CAD presently has approximately 75 open bug reports of which 50 are unassigned. Read the comments and status to see if the bug has been confirmed/reproduced.

This task involves going through those reports and REPRODUCE at least 10 of the ones that have not been confirmed. When you can reproduce the issue being reported, you'll comment on the thread to state as much and attach any data you used to reproduce the crash.


User Interface

Tasks related to user experience research or user interface design and interaction


Create an ISST screenshot or animation

Everyone loves to see screenshots and animations of software in action. We use both in our marketing and outreach. See some of the examples below that we already have.

Create an awesome screenshot and/or animation of our 'isst' tool in action. It's an interactive geometry viewer interface. It should be graphically interesting and give some sense of capability. You should import a visually complex and interesting model with LOTS of polygons and detail.


Note that we have several screenshot tasks. Note you may have to go through some or our basic MGED tutorials (see docs section on our website) just to be able to display geometry. Finally, give others a chance if you already completed one of the other screenshot tasks. ;)


Categorize all of BRL-CAD's commands into a spreadsheet

BRL-CAD is a suite of more than 400 processing tools, image tools, geometry converters, and more. There is an existing spreadsheet that characterizes all of the available commands in terms of inputs, outputs, and options, but there is insufficient characterization of BRL-CAD's commands as to how they logically group and work together.

This task involves building up a spreadsheet that lists all of our commands, describing a finite set of command categories, and characterizing all commands into those categories while filling in the spreadsheet with details for each command.


  • A spreadsheet template will be provided.


Design a Cover Photo for Facebook page (and other social networks)

BRL-CAD got it's logo changed, and it's website is undergoing a change. So this re-branding of BRL-CAD also requires a good, well designed and attractive cover photo for the BRL-CAD's Facebook page or other Social Media Appearances. It should feature a good tagline telling some killer feature of BRL-CAD, BRL-CAD's new logo and/or some illustration/image regarding the feature highlighted in tagline.

It should be consistent with the color scheme of our new website design.

New website design


Design a banner ad for BRL-CAD

BRL-CAD is one of the oldest open source communities. This community has a good following, so we want to give a chance to everyone so that they can show their support to the community by adding a banner ad in their website. You have to create a banner ad that can be embedded in the website by copy pasting some simple lines of code (basically an iframe).

Such a banner ad can also be used in various sections of our own website.

The task requires you to create a CSS3 based animated horizontal and vertical banner add, highlighting some feature of BRL-CAD or making some call to action. This call to action can be joining mailing list, or signing up for community, or link to latest post etc.

For Inspiration and tutorial refer


Creating Motion Typography video for BRL-CAD

BRL-CAD has a lot of great features that can be highlighted. A motion typography video highlighting these features would be a wonderful addition to the front page of website.

This task requires you to create a motion typography video that will convince user to give BRL-CAD a try, it could be titled something like "x reasons to choose BRL-CAD" or anything similar (give your creative minds a flight). The video should not be more than 2 minutes.

For inspiration about what a motion typography, see


Create a screen-cast for BRL-CAD

Getting started with BRL-CAD is sometimes not so smooth. A screen-cast giving a tour of BRL-CAD's GUI and the steps involved in creating the first model will make it easy for users to get started.

For this task you need to install BRL-CAD on your computer. Create a very basic model in it and record your screen as you create the model. It should also give a tour of BRL-CAD's workspace. You can choose model of your choice. Keep something very basic and easy for the first time users.


Loading Google charts from API

A basic wrapper of GCharts has been implemented a while ago : With the google charts improving their API system which wasn't around then, see if the code could be optimized so to get the charts the optimal way.


When You're Done

For non-code, just send us your file(s). For code changes, you will be expected to provide a patch file. Make sure you read your patch file before submitting it. Make sure your patch file will apply cleanly to an unmodified checkout of BRL-CAD:

svn co brlcad.edit
cd brlcad.edit
# make changes
svn diff > ~/my.patch
# read ~/my.patch file with text editor
cd ..
svn co brlcad.fresh
cd brlcad.fresh
patch -p0 < ~/my.patch
# submit your patch file to our patches tracker