Dweets by u/pavel

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.

Try the new frontend: beta.dwitter.net
Current theme challenge: #Opposites

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pavel

function u(t) {

for(let i=c.width|=0,p=355/226;i--;x[i&5?'arc':'moveTo'](960,540,2e3/z,b=p/4*((i>>3)+S(i*p)/2+4*t+z/2),b))z=2-4*t%1+(i>>7)+C(i*p)/2;x.fill()

Jan 11 2020 8:41 PM UTC

}// 140/140

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Aw this is broken in Safari

u/aleamb

#tunnel #d3

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pavel

remix of d/17068 by u/pavel

function u(t) {

for(i=c.width|=0;i--;x.fillRect(960-p/h,540+q/h,5,5))j=i>>8,f=g=>2%~j*g(9696*j-t)+3**!j*g(578*i),p=f(C)-3**.5*S(t/16),q=f(S),h=(p*p+q*q)/420

Jan 11 2020 9:02 AM UTC

}// 140/140

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Eight kissing circles 2

u/pavel

Using map-the-dots method. As you can see circles stay circles but they scrunch and stretch along their path.
u/yukulele

https://en.wikipedia.org/wiki/Steiner_chain
u/katkip

WOW

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pavel

function u(t) {

T<99&&D.every(d=>d.p>p+T|d.p+d.T<p|d.q>q+T|d.q+d.T<q)?x.strokeRect(p-=2,q-=2,T+=4,T):(D=t?[...D,{p,q,T}]:[],p=490+99*t%900,q=90+p*p%900,T=0)

Jan 11 2020 1:04 AM UTC

}// 140/140

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Squares that create a #square #waitforit

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pavel

remix of d/17152 by u/KilledByAPixel

function u(t) {

for(i=c.width|=p=g=>333*g(j)+r*g(i);j=~~(--i/96)/3;x.fillRect(960+p(C),540-p(S),8,8))x.fillStyle=`hsla(${r=(j+t)%6.3*69},69%,42%,${1-r/222}`

Jan 11 2020 12:16 AM UTC

}// 140/140

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pavel

remix of d/17103 by u/pavel

function u(t) {

h=n=>n&&x.isPointInPath(X+R*C(n),Y+R*S(n))|h(n-1)
R<169&&!h(99)?x.arc(X,Y,R,0,7,x.moveTo(X+R,Y,R+=8)):(X=t%20*96,Y=X**5%1080,R=2)
x.stroke()

Jan 10 2020 3:32 AM UTC

}// 140/140

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isPointInPath

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pavel

remix of d/11225 by u/veubeke

function u(t) {

T<150&&!D.some(d=>Math.hypot(d.p-p,d.q-q)<d.T+T)?x.beginPath(x.fill(x.arc(p,q,T+=2,0,7,0))):(D=t?[...D,{p,q,T}]:[],p=t**7%2e3,q=p*p%1e3,T=0)

Jan 8 2020 6:07 AM UTC

}// 140/140

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Blots

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pavel

function u(t) {

for(c.width|=i=4;i--;x.fill(x.arc(96*(8+i%2*4+2*o+C(a=Math.PI*(o?q:-q))),540+96*S(a),96,0,7)))q=t+3*(i>1),x.beginPath(o='001221'[~~q%6]-1)

Jan 7 2020 11:54 PM UTC

}// 138/140

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Points

Show more comments…
u/pavel

Credit https://www.reddit.com/r/loadingicon/comment…
u/tylertoomey

Can you explain how you are declaring your variables? specifically in "8+i%2*4+2*o+C" you reference 'o' and 'C' before they have even been declared -- I think.
u/pavel

for(i=9;i--;/*code here*/)/*runs after code here*/
u/ivylab

Exactly the other way around, isn't it? First the code after the bracket runs and then the code in the brackets. Your declaration is behind them. c.width=1e3;for(i=9;i--;x.fillStyle='red')x.fillRect(112*i,0,100,1000) shows that too.
u/sigveseb

Or in other words, a for loop for(A; B; C) D; will run the different parts in this order: A B D C B D C B D C .. B
u/ivylab

Exactly what I think and meant. Well written @sigveseb
u/joeytwiddle

beginPath, arc and do-si-do 🕺💃 🎻
u/UEZ

#dance

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pavel

function u(t) {

for(c.width=640,i=8;i--;x.stroke())x.beginPath(r=150*2/3*(i>1)),x.arc(320+r*C(a=Math.PI/3*i+t),180+r*S(a),150*(i?1/3:1),0,7)

Jan 4 2020 9:07 PM UTC

}// 124/140

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d/17063 #explanation

u/pavel

If you take every point on this picture, turn it into z=x+i*y and feed it through (sqrt(3)+z)/(1+sqrt(3)*z) then decode the resulting complex number as (x', y') and put a point there, you will get d/17063.
u/pavel

Of course you can't take infinitely many points so you will get a pixelated version. To get a proper version you need to solve the equation for the new, mapped, circle given the old circle so that you can use x.arc..

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pavel

function u(t) {

for(c.width=640,i=8;i--;x.stroke())x.beginPath(R=3+12**.5*C(t+=22/21)),j=i<2,x.arc(320+150*(2*!i-j),180+260*S(t)*!j/R,130/(j||R*R)**.5,0,7)

Jan 4 2020 12:23 AM UTC

}// 139/140

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Eight kissing circles

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u/pavel

These are the circles e^is, 1/3*e^is, 1/3*e^is + 2/3*e^i(n*pi/3+t) for n=0..5 transformed via the conformal map (3^.5+z)/(1+3^.5*z)
u/yonatan

Fascinating, but incomprehensible :)
u/yonatan

my best guess: z in the map is coords as a complex number, i is sqrt(-1), e is euler's const? no idea what's s
u/pavel

You got it. s is just a parameter, a real number. If you plot e^is in the complex plane you get a circle (https://en.wikipedia.org/wiki/Euler%27s_form…). Then that map magically moves and resizes things but keeps circles as circles.
u/pavel

This d/17068 is what the circles look like before the mapping. The mapping moves the inner one sideways, outside of the outer circle, and resizes it to be the same size, meanwhile the moving circles keep touching.
u/pavel

Check out https://jsfiddle.net/umL3t1he/9/ on desktop
u/katkip

#apolloniangasket

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pavel

function u(t) {

f=n=>n&&C(t*f(n-1))
t?X=(333+X+C(a+=f(9)/15))%333:X=Y=a=98
Y=(180+Y+S(a))%180
for(i=2;i--;x.fillRect(X*6-d*S(a),Y*6+d*C(a),8,8))d=i%2?24:-24

Jan 3 2020 5:16 AM UTC

}// 140/140

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Invisible car

u/andrea270872

nice. could it work to create a zen-garden look?

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