Top 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(c.width|=p=300;e=p--**.9%1;x.fillRect(960+r(0)/z,200+99/z,s=9*e/z,s))r=d=>p/(1+e*C(a=t/4+p))*C(a+p+d)+2*p/(1/e-e)*C(p+d),z=.5+r(1.6)/800

Feb 28 2019 6:54 AM UTC

}// 140/140

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Galaxy

u/pavel

300 bodies which individually only interact with an infinite mass at the center
u/pavel

Each body moves around an ellipse, the orbits are accurate. However, the movement speed is a very rough approximation.
u/pavel

Naively drawing an ellipse centers it around one of the focal points, however moving a body on this path slows the body down near this focal point and speeds it up near the other one.
u/pavel

The opposite effect is needed. So this code still moves a body around an ellipse but it re-centers the ellipse on the 'other' focal point.
u/pavel

In polar coordinates the difference between the x and y coordinates is a phase shift of pi/2 ~ 1.6

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pavel

function u(t) {

for(c.width|=i=99;S[u[t]=t]=x[t]=i--;x.fillRect(960+(u[i]+=S[i]-=u[i]/d),540+(x[i]+=C[i]-=x[i]/d),C[t++]=9,9))d=(u[i]**2+x[i]**2)**1.5/7e3

Feb 28 2019 5:17 AM UTC

}// 138/140

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#physics #orbit #orbits

u/pavel

Funky start due to lack of chars but quickly settles. Imagine a black hole in the middle.

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pavel

remix of d/11463 by u/cantelope

function u(t) {

with(x)for(c.width|=i=6,scale(9,9),q=C(4*t);i--;stroke(),fill())moveTo(X=64+17*i,0),arc(X-60*S(a=(q>0?i:i-5)?0:q),60*C(a),8,a-Math.PI/2,9)

Dec 18 2018 12:32 AM UTC

}// 138/140

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u/cantelope

ah! of course. i knew there had to be an easier way ;P
u/katkip

Haha nice
u/iverjo

#newtonscradle
u/pavel

For a more realistic look replace (q>0?i:i-5)?0:q with (q>0?i:i-5)?q/50:q

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pavel

function u(t) {

for(c.width|=i=23,x.globalAlpha=.1;j=99*(i-->>1);x.fillRect(-j,0,2*j,99))x.setTransform(u=-C(a=(i%2-t/3%1)*1.57),v=S(a),0,1,960+j*v,j/2-j*u)

Dec 4 2018 12:21 AM UTC

}// 140/140

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#pyramid

u/pavel

Messing around with setTransform

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pavel

remix of d/10477 by u/pavel

function u(t) {

s=3+15*t%6;i=960-s*365;j=s*210;for(c.width|=a=n=0;n<1e4;T=n=>n&&T(n>>1)-n&1)T(n++)?x.lineTo(i-=s*C(A=a++*355/339),j+=s*S(A)):a-=3;x.stroke()

Nov 6 2018 4:56 AM UTC

}// 140/140

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#koch #fractal

u/13thptr

#zoom #loop

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pavel

function u(t) {

for(X=7;X--;)for(Y=4;Y--;)for(i=4;i--;x[i+q&1?'clearRect':'fillRect'](135*(1+2*X-r),135*(1+2*Y-r),r*=270,r))q=2*t+X+Y,r=(i+q%1)/4

Apr 16 2020 4:31 AM UTC

}// 129/140

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https://www.reddit.com/r/loadingicon/comment…

u/Xen

that q=t*t+X+Y tho ;-)
u/rep_movsd

#underrated

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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

remix of d/15202 by u/pavel

function u(t) {

with(x)for(i=t?0:200;i--;i-198||clip())beginPath(fillStyle=R(a=255-i,a,j=1-i/199,.2)),fill(arc(Y=760+i,Y-420,500*(j?1-j*j:3),0,7))

Jul 30 2019 7:37 AM UTC

}// 130/140

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Poor man's ray tracing v2

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pavel

remix of d/14376 by u/pavel

function u(t) {

t?x.arc(w=960,h=540,h,0,c.width|=0):X=Y=1e3
X*X+Y*Y>2.4e5&&(r=C(t*t)*8+12,U=-X/r,V=-Y/r)
X+=U;Y+=++V;x.arc(w+X,h+Y,5*r,0,7);x.fill`evenodd`

Jun 6 2019 5:00 AM UTC

}// 139/140

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#physics #bounce updated so ball size reflects speed

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pavel

remix of d/14251 by u/pavel

function u(t) {

for(j=c.width|=0,s=84;i=j-->>1;x.fillRect(0,0,(o?Y:i)%2*s,s))Y=i>>5,o=[0,1,j%2,j%2][t&3],x.setTransform(!o||.5,!o,o,o||.5,i%32*s-s,Y*s-s)

May 28 2019 6:00 AM UTC

}// 137/140

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Houndstooth

u/Cloud

This is my teacher's dress :D

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