d/25493 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

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    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.

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taupelink

remix of d/25492 by u/taupelink

function u(t) {

for(k=300,m=t?0:2e4;m--;x.fill())x.beginPath(x.fillStyle=R(r=m**(m%.75),i=m%k/.9,r+i,r/i/4)),x.arc(m%8*k+r*C(m),(m>>3)%5*k+r*S(m),r,m,m-m%4)

May 13 2022 6:53 PM UTC

}// 140/140

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d/25493

u/taupelink

Note: This dweet looks different on different browsers.You may see a blank column on the left edge and just to the right of center. Those were not there when I composed the dweet on iOS. They can be eliminated by replacing m-m%4 at the end with m-m%4+(m%4?0:7)
u/taupelink

I think what's happening is, different environments interpret arc differently in case the start and end angles are the same. In iOS, a full circle is drawn (which is what I intended). Elsewhere, nothing is drawn (hence the white columns you may be seeing).
u/pavel

As far as I know it is just Safari that has a bug with arc, where the two angle terms do not simply get %(2*pi) treatment. If the angles are sufficiently large, like 10pi-ish, the arc breaks and draws weird lines. So you have to ensure the angles are small manually :/
u/taupelink

well, the question here is what happens when the angle difference is zero? I suspect this is another quirk of Safari/iOS: when the angle is zero, it defaults to drawing a full circle.


      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)

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