blog.Habrador.com

The one who's running this blog is me, Erik Nordeus. I'm an imagineer (creative engineer) who's interested in the intersection between art and engineering.
This is my portfolio: Habrador.com

Explaining the Hybrid A Star pathfinding algorithm for selfdriving cars

Let's say you are standing somewhere in a room and would like to find the shortest path to a goal. You can see a few obstacles, such as a table, that you would like to avoid. The easiest way to solve the problem (if you are a computer) is to divide the room into many small squares (cells) and then use the common A* (A Star) search algorithm to find the shortest path. But what if you are a car and can't turn around 360 degrees like a human can, then you have a problem! Well, at least until you learn the Hybrid A Star search algorithm . With that algorithm you will be able to find a drivable path to the goal. The reason I wanted to learn the Hybrid A* algorithm was that I took a class in self-driving cars, where the teacher showed a really cool video with a car that drove around in a maze until it found the goal: The problem was that the teacher didn't explain the Hybrid A* algorithm - he just explained the classic A* algorithm , so I had to figure it out on my own...

How to implement colormaps like Rainbow and Viridis in code

I've been working hard on making my very own digital wind tunnel in the Unity game engine. It's based on a tutorial from the YouTube series 10 Minute Physics called "How to write an Eulerian Fluid Simulator with 200 lines of code." I translated the code from JavaScript to C#, and I open sourced the implementation here: Ten Minute Physics in Unity. To simulate any fluid you need to study the Navier-Stokes equations . These are very hard to solve. In fact so hard they are a part of the Millennium Prize Problems where you can win a million dollars if you gain some insight while solving them. Therefore you need to simplify them. But even though they are simplified you can still see the vortex shedding that's happening in real wind tunnels if you put a cylinder in them. I thought this was really cool because the simulation part is just 200 lines of code running at 70 fps on the CPU. Common colormaps I wanted to improve the wind tunnel by making it more realistic...

Cybertruck Prototype vs Final Production Version - What Changed?

In 2019 I started making a 3D model of the Tesla Cybertruck prototype version in Blender. Four years later, in 2023, Elon Musk finally released the production version of the Cybertruck . Since I've studied every millimeter of the prototype version to be able to make the 3D model I thought it would be interesting to make a comparison of how much changed during the four years. Exterior Front bumper. The black front bumper has become bigger and smoother, most likely to improve the aerodynamics of the vehicle. They also added a mudguard for the front and rear wheels attached to it. Front window. Like the front bumper has become smoother to improve aerodynamics, so has the front window which is now rounded - it used to be completely flat (To be honest I think this is the case anyway - it is not rounded much to make it super visible). Wheels. The wheels are roughly the same as the prototype vehicle wheels - they added som threads to the side of the wheel. I thought t...

How to make a texture atlas template the smart way

Using a texture atlas is a smart way to improve the performance of your game and minimize the number of textures you need to keep track of. A texture atlas is basically a square image you split into smaller squares with the same size. For example, this is how Minecraft's texture atlas looked like in 2011: The boring part is to make the template. I used to create a texture with the size I want the texture atlas to be, like 2048x2048. If I wanted to split it into 8x8 sections, I made a new texture with the size 256x256 with the color black. And then I copied the 256x256 texture into the texture atlas to create a chess pattern. But what if I wanted the texture atlas to be 4096x4096? Then I would have to redo it again! A better way is to first create a tiny image with the size 8x8 (I'm using Paint.Net ). Then you use the Pencil tool with a black color to create a chess pattern: Then you scale the tiny image to the size you want the texture atlas to have: Image → Resize. Set the si...

How to actually delete Rigid Bodies in Blender

I've been simulating ball physics in Blender - and it has been a little bit of a struggle. Yesterday while testing out different behavior of balls I realized that if I deleted some of the balls - Blender didn't actually remove their colliders. I couldn't see the balls themselves but I noticed that the deleted balls collided with the visible balls. I tried to restart Blender and clear the cache, but nothing worked. This morning I decided to create a simple test scene to learn what is actually going on. Is it a bug, or am I just not understanding how Blender's physics system is working? This is the test scene in Blender: And this is how the Scene collection hierarchy looks like: The cube is a passive rigid body and the spheres are active rigid bodies. To see which objects are part of the rigid body simulation, you can click on Display Mode and then on Blender File: And then you navigate to the RigidBodyWorld collection. You can see that all five of our rigid bodies are ...

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