relativisticgame

Week 40: Robot's video and work on collisions (Patreon)

Published:

2023-08-11 16:43:15

Imported:

2026-06

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I continued to work on the CPU implementation of graphics primitives for the Robot’s screen. I spent one day creating a short video to capture and showcase the end result. I posted the video on TikTok and a slightly modified version on YouTube, as a YouTube Short. This was a bit of an experiment to check whether Tiktok/YouTube dev-log videos would get me more reach than posting on Twitter. So far my success on Twitter has been limited to say the least. It seems the answer is that indeed I get more traction on YouTube (not that much on Tiktok actually), although I worry a bit that my current subscribers would find the videos annoying.

I started working on improving the code that handles collisions and interactions between physical objects in the game. I wrote down some of my thoughts, taking inspiration from the current implementation in my game, but also trying to extend it. I find that writing down things helps me a lot in tackling complex problems. I’ll publish the article on my site. Next week, probably.

Files

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Born rigidity: rigidity in space and time

#shorts In classical physics a body is defined as rigid when the distance between any two points of the body does not change in time. But in Special Relativity the spatial distance between two points is observer-dependent. Two different observers see different spatial distances, depending on their speed relative to the body. For this reason, extending the concept of rigidity to Special Relativity is non-trivial. One natural way of doing this was first formalized by Max Born in 1909. Born-rigidity is somewhat surprising. Born-rigid bodies cannot be brought to a state of rotation without violating the rigidity constraint (although a body that is already in rotational motion can well satisfy the Born-rigidity constraint.) For this reason Born-rigid bodies have only 3 degrees of freedom, the translational ones. This is different than classical mechanics where rigid bodies have 3 translational degrees of freedom plus 3 rotational ones, 6 in total. Despite this, Born-rigid bodies can end up rotating as an effect of Wigner rotation. This may sound contradictory. They key point to understand is that Wigner rotation is not a freedom of the body, it is fully determined by the body's translational motion. Another quite interesting fact about Born-rigidity is that Born-rigid bodies have a maximum acceleration they can withstand before the rigidity constraint is violated. The bigger the body is and the smaller the maximum acceleration is. === Technical details === The flames point along the direction of the spatial part of the four-acceleration evaluated at the centres of the engines. The rendering of the flames is itself not accurate and should be considered more of an aesthetic element of the animation. The robot's LED screen is also updated instantaneously and is currently unaffected by the motion of the robot. I plan to make the LED screen accurate in future versions of my software. === Useful links === - Game blog and formulas, https://relativisticgame.net - Born rigidity, https://en.wikipedia.org/wiki/Born_rigidity === Soundtrack === The Music I Use: https://www.bensound.com/free-music-for-videos License code: NNSC20CYC0XLY7K6