d/23823 figure 3 by taupelink

function u(t) {

c.width=1920 // clear the canvas
for(i=0;i<9;i++)
x.fillRect(400+i*100+S(t)*300,400,50,200) // draw 50x200 rects

} // 122/140

Please log in (or register) to post a dweet (copy-paste the code somewhere safe to save it meanwhile)


    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.

show FPS hide FPS share fullscreen

taupelink

remix of d/23806 by u/taupelink

function u(t) {

k=120;for(i=k;i--;)
f=i*t,X=f*f%16,Y=X*f%4-2,
x.fillStyle=R(0,k+k*Y/2,k+k*C(Y*1.57)),
x.fillRect(k*X,540+k/Y,k/5**t,i)

Sep 10 2021 3:57 AM UTC

}// 118/140

Please log in (or register) to post as a new dweet (copy-paste code somewhere safe to save it meanwhile).

d/23823 figure 3

u/taupelink

briefly: Y ranges from -2 to 2. Below the middle line, Y is positive and there's more green than average. In the large top and bottom areas, Y is between -1 and 1, and there is more blue than average.
u/taupelink

Note the formula for the top of the rectangle, 540+k/Y. This breaks the window up into four horizontal bands. From top to bottom, they are: -2<Y<-1, -1<Y<0, 1<Y<2, and 0<Y<1 respectively.
u/taupelink

Correction: -1<Y<0 is the top band, -2<Y<-1 the second from the top.
u/taupelink

The green component formula is k+k*Y/2. This is greater than k when Y>0.
u/taupelink

The blue formula is k+k*C(Y*1.57). This is greater than k when C(Y*1.57)>0, i.e., when -1<Y<1.


      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)

dwitter.net