RoboAnt: How to Make your Own Robot

Here are three blog posts I wrote on the University of Edinburgh Insect Robotics Group blog that describe in detail how I made RoboAnt.

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TheHunt mutates!

Those who follow my github (I know there aren’t many of you ;-)) already know about the exciting changes in TheHunt the past few weeks. For everyone else – listen up!

Firstly, zooming in and out! Works well and intuitive (made me realize the default world size is not so big…)

palette_knifepalette_inactive palette_net








Secondly, the palette I promised a while ago is finally here. While it doesn’t impress with looks, the functionality is so so useful! Let me tell you – every time you touch the screen the palette appears instantaneously, allowing the quick change of tools. What if you want to use your tool instead? All is good, just drag outside the boundaries of the palette and it disappears, letting you either finish a net or cut something.

And last but not least, the Prey started to evolve! The evolution system I came up with is:

  • Prey body is divided into body parts – currently Head, Body and Tail. They are pretty much independent and only need to know the points where they bind with their surrounding body parts
  • This gives them freedom to evolve independently as well. Head, for example, starts off without eyes or ears (or whatever fish have that lets them hear) and has two mutations – eyes (eyes appear on the graphic and allow it to see Algae in the front) and hearing (head gets bigger, prey runs away from ploks!)
  • Currently all mutations happen at random and have a chance to happen on death and on GM food eaten

I’m excited that TheHunt begins to look much more like a game now! I’m going to be back soon with more mutations ^_^

TheHunt – making progress!

The past month has been really exciting for me – please excuse my absence, but in my defense, I found an internship for the summer! Has to do with Android and security – two of the things that excite me, so I’m happy ^_^

Now on the topic – TheHunt got three cool improvements:

  • A Knife tool! Still haven’t made the cool contextual menu, but a long click now switches between Net and Knife. What does Knife do? Let me show you:



  • Prey now actually chases after user-generated food with priority – this makes the idea of feeding the fish to lure it out of algae and catch it much more feasible!
  • The Net tool now interacts with the environment better and catches algae and food in it’s range. This changes the way score is calculated a bit – 10 points for a Prey, -1 points * size for Algae and -1 point for Food caught (tentative)

Finally, a playable TheHunt! But this is only the beginning. Coming soon:

  • Prey has 3 states, the way it currently is and 2 upgrades. The states change the Prey’s appearance and intelligence, and the Prey upgrades state when it eats a food from the player (explanation is, the food is GMO) and returns to normal state once caught. This way, the more you feed the fish without catching it, the more difficult it gets to catch it. Yay!
  • Zoom in/out controls, finally
  • Some animations to make it look fancier – algae shiver, GMO food shines

Once this is done, TheHunt will be much closer to release! As always, please let me know if you have cool ideas or don’t like mine – now is the best time to change stuff!

TheHunt – The Future

Recently I was struck by a few nice ideas about TheHunt and I’m in a hurry to write them down. Here we go:

  • Knife tool. Been thinking for a while how to deal with fish hiding in a huge algae and now I think I figured it out – using the knife to cut the big into small ones. Should be easy to implement, I give it half a week.
  • Contextual menu on long-click. Long press somewhere, you get a nice pop-up menu where you can change tools, maybe request info about the object picked and other undecided stuff. Navigate in it without releasing the press. Can be tricky, I give it a week.
  • Simplified interface. Just one number in the top middle, showing score. Long press for a menu, maybe pop-ups with more information if needed. After contextual menu is implemented, only pop-ups will be missing.
  • Nicer font. I will experiment, but I’m thinking of something that looks hand-drawn. Easy to implement, but may require some time to find a proper font. I give it a day.

A quick concept to show the simplified interface and the contextual menu (didn’t include the knife and the nicer font)


In a week or two I hope to have made a visible progress towards a more playable TheHunt!

Rendering Text in OpenGL 2.0 ES on Android

Hello all,

I have just finished porting fractious’s Rendering Text in OpenGL on Android to OpenGL ES 2.0 (this is the mobile version of OpenGL 3.0 and the main difference with the older versions OpenGL is having acces to the shaders, which allow us to run code on the GPU).

I had to do this because my project TheHunt uses, you guessed it, the newer version. Reason is that it would allow me to do some nifty shader tricks… some day 🙂

So here is my code – Feel free to use it for whatever you want as it is licensed under the CC0 1.0 public domain license.


The example application, Texample2

Some implementation details:

  • I firstly started by simply converting the OpenGL ES 1 commands to the newer version. The Model, View and Projection matrices were passed using a uniform variable to the shaders, i.e. all the letters used the same matrices. This was good enough to produce horizontal text
  • In TheHunt I use text to label events (fishbone flops, net snatches), and I need this text to be tilted (it would be somewhat boring otherwise). For this I needed to be able to assign individual model matrices to each word. A bit tricky, but using Sprite Batching in OpenGL ES 2.0 | Anton Holmquist as inspiration I managed to do it. In short, instead of an uniform Model-View-Projection matrix, the vertex shader has an uniform array of matrices. I fill this array with an individual matrix for each letter and also pass a matrix index attribute for each vertex (the exact same method suggested by Anton Holmquist.) The result is that each GLText::draw call can tilt the string drawn with a certain angle (it can now receive an angle argument, in degrees).
  • The last catch was drawing color text – at first, all text was coming out black for me. The reason turns out to be that the texture is defined as grayscale, so in the fragment shader we need to multiply the color we want for the text (passed as uniform u_Color) with the grayscale value (called W in OpenGL) of the texture (not with the whole texture color, because it is something like [0, 0, 0, grayscale] which was resulting in the all black text):

gl_FragColor = texture2D(u_Texture, v_TexCoordinate).w * u_Color

— from

That’s all I can think of, and the result is efficient text drawing in OpenGL ES 2.0, and more importantly in TheHunt, where you can expect a nice GUI to appear soon!