The 6th meeting of the Recreational Computer Programming Group was held on June 9th, 2013 at Houston's hackerspace, TX/RX Labs.
Chris Ertel presented an interesting web app from the Multi Robot Systems Lab at Rice University which allows you to control a simulated swarm of robots to perform various tasks.
Steve Cameron (that's me) presented an implementation of Jeremy Van Grinsven's idea to make a software crosshatching algorithm. The algorithm works by producing several layers of parallel lines, each set of parallel lines rotated to various angles over the source image. Each line is drawn as a series of very very short line segments. For each line segment, the underlying source image is sampled, and if the corresponding location on the sourceimage is "dark enough", the line segment is drawn, otherwise, it is omitted. For each layer of parallel lines, the "dark enough" threshold is raised. This seems to be enough to produce a reasonably good looking crosshatched image. Jeremy also took the output of my algorithm and executed it in a laser etching on wood to produce a fascinating image of Spock, from the original Star Trek TV series.
I also briefly presented my ongoing progress on my video game, Space Nerds in Space, specifically progress on the software 3d renderer, asteroids, and the implementation of a 3d "starfield" effect.
Mark Sullivan presented some ideas about how some of his CAM software for computing tool paths from CAD designs worked, and in some cases didn't work, and we discussed various approaches to the problem, and speculated about what might be going wrong in those cases which didn't work right. I don't know that any real progress was made on the topic, but it was an interesting and informative discussion nonetheless.
Relevant links:
http://mrsl.rice.edu/ (Multi Robot Systems Lab)
http://swarmcontrol.herokuapp.com/ Web app allowing you to control a simulated robot swarm to perform various tasks.
https://github.com/smcameron/crosshatcher
https://github.com/smcameron/space-nerds-in-space
The next meeting of the Recreational Computer Programming Group will be held July 14th, 2013, at 1:30pm at TX/RX Labs.
The third meeting of the Recreational computer group took place today, March 10, 2013, and was well attended. Edwin G. presented some slides about the ant colony optimization algorithm which has applications in scheduling, routing and other areas. He also presented some information about the Maven build system used by the Apache project. Marlin Mixon showed us his html5/canvas implementation of a game called Floodwar, in which players (one of which may be the computer) select elements of a colored grid to capture connected grid squares of the same color in an attempt to win the game by acquiring a majority of the terriitory. Steve Cameron (that's me) presented a stochastic 3d castle model generator implemented as a C metaprogram which outputs an openscad program to create the castle model.
The next meeting of the Recreational Computer Programming Group will be on April 10, 2013.
"Flood War"
Related links: FloodWar
opencscad
Ant Colony Optimization Algorithm
Maven.
A couple weeks ago TX/RX member Jeremy G. picked up a broken CNC mini-lathe at a local pawn shop for fifty bucks and brought it in. Within a few hours, he and other members Chris K., Roland K, and Greg S. had it up and running under the control of EMC2. Greg found a replacement for the missing shield on ebay, and now we have a neat little CNC mini-lathe.
If you missed the open house this past Friday night (02/15/2013) at TX/RX labs, you missed a good show. Jeremy Van Grinsven brought in the RGB laser projector he's been working on over the last month. The projector contains three lasers, red, blue and green. The beams are conjoined by sending them through, or bouncing them off dichroic mirrors -- mirrors which either transmit or reflect light depending on the frequency of the light. Once conjoined, the beams bounce off two galvanometers, which are mirrors mounted on motors that vibrate similarly to the voice coil within a loudspeaker. The mirrors are controlled by the amplified signal emanating from a sound card -- so the left and right channels of a sound card control the x and y deflection of the conjoined beam.
On the software side, the openlase library is used to map familiar line drawing primitives (lines, circles, etc.) to sound card output. From there, it was an a fairly easy step to adapt Word War vi, a vector based graphics game by Steve Cameron (that's me) to work with the projector -- the main thing which needed to be done was to remove and simplify things to meet the laser projector's line budget, as it is relatively slow compared to a raster graphics display. Additionally Laser Lander, a lunar lander type game, was hastily written with the laser projector expressly in mind.
Video of the projector in action may be seen here: Jeremy's RGB laser projector in action
This past Sunday, Feb. 10th, the 2nd meeting of the Recreational Computer Programming Group was held. Chris Ertel showed us some cool effects dynamically applied to webcam output via OpenGL shaders, and some interesting procedurally generated maps for some sort of zombie infection game. Marlin Mixon demonstrated an Android app that he's been working on to enable people to find satellites visible to the naked eye in an urban environment. Steve Cameron (that's me) demoed a kaleidoscope-like application inspired by the ancient video game "Qix", a pseudo-physics based stippling algorithm implemented in python, and a lunar lander game designed to work with a laser projector via the openlase library.
Relevant links:
- Qix-kaleidoscope
- Stipplebomb
- Laser-lander
The next meeting of this group will be held March 10th, 2013. Hope to see you there.
Over the course of a week or so, TX/RX labs member Jeremy Van Grinsven built this amazing Arduino driven edge-lit laser-etched acrylic zoetrope showing an animation derived from another TX/RX member’s video game, Word War vi [full disclosure, that other member is me. -- Ed.]

Here it is on YouTube
Here is Jeremy’s blog post about this project if you’d like to know more about it.
Always wanted to build a go-kart but don’t know how to weld? Or maybe you would like to make an iPhone game, but don’t know how to program? Or perhaps you have ideas for some cool electronics projects, but don’t really know how to get started? More likely, you have even better ideas. Our Fall DIY class series is just the thing to help get your projects out of your head and into the real world.
We offer hands on classes in all areas of Fabrication, Design, Programming, etc. Examples include Welding, CNC, Arduino, C Programming, CAD, 3D Printing and Stepper Motor Design to name a few. Check them out at our class registration page. Nowhere else in Houston will you be able to learn so much in such a short time and get hands on experience with such exciting topics, and all for such reasonable prices.
This year, all of us at TX/RX Labs are very pleased and excited to be in a new and much larger facility at 205 Roberts St., Houston, TX 77003.
Programming and CAD classes
- Intro to Inventor (3-D Comp Aided Design)
- 3d Printing
- Intro to 2d Cad/Drafting
- Calculus for the Practical Person
- Intro to C
- Intro to HTML/CSS
- Intro to Programming: First Principles
- Intro to DJANGO
- Automation for Non-Programmers: Ladder Logic
- Learning Javascript
- Intro to Arduino
- Advanced Arduino
- Beginner iPhone/iPad Development
- Intermediate iPhone/iPad Development
- Math for Game Devleopment
- Intro to Andriod Development
- Intro to Ruby on Rails
Electronics/Mechanics classes
- Intro to PCB Layout with Eagle
- How to create your own PCBs
- Oscilloscope Laboratory
- Intro to Digital Signal Processing
- Intro to Stepper Motors
- Intro to Soldering
- DIY Multicopter Build
- Intro Analog Theory
- Intermediate Analog Theory
- DIY Electric Vehicle Conversion
Metal/Wood/Plastic Working classes
- Brazing
- Welding I
- Welding II
- Laser Cutter Class
- Intro to Plasma Cutting
- Woodworking: Build a Chest
- Intro to CNC
Bike Tech classes
- Beginner Maintenance
- Wheel Truing
- Intermediate Maintenance
3D Art Houston is a relatively new artists’ group focused on three-dimensional art forms. 3D Art Houston members will be meeting at TX/RX Labs on Wednesday, August 15th at 6 p.m. to gain a better understanding of the resources and talents there.
Members work in clay, iron, glass, wood, textiles, plaster, brass and building materials, such as stucco and augmented concrete.
Making three dimensional art always has an engineering component, if only because the art must be stable and remain exactly as placed, even if that place is simultaneously cantilevered, counter-balanced and rotating.
What: 3D Art Houston meeting
When: Wednesday, August 15, 2012, 6 p.m.
Where: TX/RX Labs, 2010 Commerce St, Houston, TX 77002
Program: 3D Art Houston artists Nell Gottleib, Joy Mullett and Lynda Stoy will brief members on what they learned in order to use the laser cutter to create art. Members will tour the Tx/Rx space. Refreshments will be served.