gtec-demo-framework VS SolarSystem

While the principle in that article is correct it’s unfortunately a lot more complex to solve correctly. See my answers to a similar problem here. You can also check this app

Here are some details that should help. You can also look at this example

There is also this implementation.

Take a look at this

You could try running the samples from the NXP demo framework to see if they show the same behavior. I expect the GLES2.S06_Texturing sample would be easy to see it on.

If op decides to use bitmap fonts for small sizes there is some valuable tips here

Well here is a real world large project with 452 packages and 170 applications that run on five operating systems that has been using this since 2014.

Does it handle DPI properly? If not you might find this useful.

Check this guide

Maybe this can help.

I also ported it in an opengl project: https://github.com/aromanro/SolarSystem

I've got a lot of physics-related projects on GitHub, most of them use matrices, even if sometimes it's not obvious. For example, this one: https://github.com/aromanro/SolarSystem uses matrices for changing from one coordinate system to another, rotations and so on.

I also have a solar system simulator, it used at first velocity Verlet, then I switched to Verlet since I really didn't need the velocity in it: https://github.com/aromanro/SolarSystem

There are countless of open source programs that do that, you just have to look over the sources. For example, one of my projects: aromanro/SolarSystem: A solar system simulator with velocity Verlet, using OpenGL for displaying. (github.com)