Optical illusion: Look at the center do… by iverjo

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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iverjo

function u(t) {

for(i=13;i--;)k=i!=12,x.beginPath(),x.arc(960+400*k*C(j=i*.523),540+400*S(j),9+50*k,0,7),x.fillStyle=R(a=255*k,a*(i==(t*9%12|0)),a),x.fill()

Jan 28 2017 6:59 PM UTC

}// 140/140

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Optical illusion: Look at the center dot for at least 5 seconds. What you should see is that the missing dot becomes light green. Keep staring at the same point for another 10-30 seconds, and you might notice that some pink dots will "disappear". This is due to cone fatigue in your eyes.

u/iverjo

Two characters can be shaved by replacing k=i!=12 with k=!!i
u/lionleaf

Haha, amazing!
u/iverjo

#opticalillusion


      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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