[bouLED] A pretty triangle and a pretty simulator

Last week we finally printed a triangle of the right size (see Hichem’s post). Hichem cut the led strip into smaller ones, and I re-soldered them to fit the triangle, which was not hard but took some time.

92 welding points

For the final object, we won’t have to solder 20 times as many LEDs. We’ll just put individual LEDs on triangular PCBs -we just started drawing the circuit diagrams. The point of this first triangle is to be able to display stabilized animations before all the PCBs are built.

I also worked on the 3D visualisation. Matthias had re-written the first one with PyQtGraph, because VTK didn’t suit him. But this new one had terrible performance: computing the new LED positions every frame made the framerate drop to around 1fps. Therefore, we had to write another simulator. This time, no more compromises, no more Python, just C++, OpenGL and sweat. Matthias set up the OpenGL context and let me have fun with matrices, geometry, textures and instancing. It’s not quite finished yet (not to mention glitches), but we can dynamically color each LED, rotate the model by feeding the simulator quaternions via stdin, and still get 300 fps on integrated graphics.

Virtual bouLED

When it’s done, we’ll be able to display images on it, and get an idea of the final result. However we haven’t decided yet how we’ll store and project images on the icosahedron. We’re also unsure if displaying text is possible with our relatively low resolution.

2 Replies to “[bouLED] A pretty triangle and a pretty simulator”

    1. That’s a major change, yep, we probably should have sent an email about that (but we discussed it on Telegram). The triangles would have nothing more than APA102 LEDs (chained as we did here) and connectors on the underside for SPI communication and power supply. What do you think, would that be feasible ?

      The problem is that the 3D printed triangle is a hack, there are wires averywhere that break easily, duct tape and cardboard behind it to lock the strips in place (and even then, it’s not that sturdy). We’re not convinced that it’ll be manageable as an icosahedron.

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