u(t) is called 60 times per second.
t: Elapsed time in seconds.
S: Shorthand for Math.sin.
C: Shorthand for Math.cos.
T: Shorthand for Math.tan.
R: Function that generates rgba-strings, usage ex.: R(255, 255, 255, 0.5)
c: A 1920x1080 canvas.
x: A 2D context for that canvas.
Note the intersection is fuzzy since full circle-AABB takes too much code, instead it's just circle-point + current subdivision width based radius (w*w*6.28), i.e it becomes more accurate as it converges.
This is why there are a bunch of divisions around it that would not exist with an exact test. Pavel's doesn't do this by cleverly choosing a geometry that only need intersect the top left of each square.
u(t) is called 60 times per second.
t: elapsed time in seconds.
c: A 1920x1080 canvas.
x: A 2D context for that canvas.
S: Math.sin
C: Math.cos
T: Math.tan
R: Generates rgba-strings, ex.: R(255, 255, 255, 0.5)