Coding, Geometry Joys, Java, Milestones, Murderous Maths, Physics

Pendulum Force

This is a beautiful “lecture” that Simon in his pajamas, chocolate paste adorning is face, game me Friday morning. He spoke about pendulum force, a force he was about to apply in a coding project.

The other videos form the very beginning of the lecture, with Simon plays with sine and cosine and explains why location, velocity and acceleration can be vectors and can be angles:

And this is the code where pendulum force is used. It’s an example from The Nature of Code book by Daniel Shiffman, from Chapter 3 on Oscillation:

Coding, Geometry Joys, Java, Milestones, Murderous Maths, Physics

Translating examples from The Nature of Code into Lua (Codea)

This morning Simon attempted to make a more difficult translation in the Codea app of an example from Daniel Shiffman’s book The Nature of Code (Java) into Lua. It concerned the Gravitational Attraction example from Chapter 2 of the book, Forces. Simon is happy with Codea because “It’s really readable!”, “You don’t need semicolons and parenthesis!” and all logic operators are actually typed in words (“and”, “or”, “not”).


Unfortunately, the function Simon introduced as substitute for mouse pressed release on the touch screen didn’t seem to work:

Simon did successfully translate the simple harmonic motion example from Chapter 3, Oscillation: “I use trigonometry!”

For this example, he had to look up a complex formula for mapping a range to another range on the internet b1 + (s – a1)*(b2 – b1)/(a2-a1) “because map function doesn’t exist in Codea, so I wrote that function”.

Swapping the axes:



Coding, Java, Physics

Playing with examples on Forces and Oscillation from The Nature of Code

Playing with examples from Chapter 3 of The Nature of Code, Oscillation, covering trigonometry and connecting it to forces. The examples included simple harmonic motion, angular velocity and waves, as well as gravitational attraction from Chapter 2, Forces.

Simon also found a way to be like Daniel Shiffman – he programmed a large webcam canvas and shifted his Processing canvas to the side:




Coding, Geometry Joys, JavaScript, Physics, Simon's Own Code

Soft Springs (Simon’s own code)

Simon used Chapter 3 (Oscillation) of Daniel Shiffman’s book The Nature of Code as the theoretical basis for creating his own code. First, he played around with what he calls “soft springs” – multiple spring arrays connecting multiple particles (some of them locked but most of them moving) – allowing for most interesting designs thanks to spring force.

Simon called the video below “a mess” that “doesn’t look promising”, but to me it’s my favourite pattern. To me it resembles a constructivist poster turned alive, something like an El Lissitzky animation:

Other soft springs step by step (Simon explains what soft springs are in the first video):

Simon eventually stepped over t trying to create sets of springs and particles that unfold into certain geometrical shapes, like a trapezoid here:

And finally, a hexagon:

Coding, Geometry Joys, JavaScript, Murderous Maths, Physics, Uncategorized

Oscillation and Drag Force: Spring Project.

Today Simon was watching Daniel Shiffman’s tutorials to learn about drag force and how to apply it when building a spring simulation in p5.js. Simon wrote the formula for drag force in Microfost Word and looked up all the variables:

Drag Force 23 Apr 2017 2

While building a spring in p5.js, Simon talks about the 3 laws of Isaac Newton:

The project is based upon Daniel Shiffman’s book The Nature of Code, specifically Chapter 3 (Oscillation). Simon spent the rest of the evening studying “simple harmonic motion”, periods and amplitudes. Here is an excerpt from Daniel Shiffman’s book:

y = sine(x)
You’ll notice that the output of the sine function is a smooth curve alternating between –1 and 1. This type of a behavior is known as oscillation, a periodic movement between two points. Plucking a guitar string, swinging a pendulum, bouncing on a pogo stick—these are all examples of oscillating motion.
This is what is known as simple harmonic motion (or, to be fancier, “the periodic sinusoidal oscillation of an object”). It’s going to be a simple program to write, but before we get into the code, let’s familiarize ourselves with some of the terminology of oscillation (and waves).
Simple harmonic motion can be expressed as any location (in our case, the x location) as a function of time, with the following two elements:
  • Amplitude: The distance from the center of motion to either extreme
  • Period: The amount of time it takes for one complete cycle of motion
Looking at the graph of sine, we can see that the amplitude is 1 and the period is TWO_PI; the output of sine never rises above 1 or below -1; and every TWO_PI radians (or 360 degrees) the wave pattern repeats.