Dweets awesomed by u/aleamb

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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Current theme challenge: #Food

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pavel

remix of d/18322 by u/pavel

function u(t) {

for(let i=1920,f=(x,y,n=256)=>x*y<n?f(x*x-y*y-.8,2*x*y+.156,n-1):1-n/256;i--;x.fillRect(i,t*180,1,3))x.globalAlpha=f(i/540-16/9,1-t/3)

Apr 18 2020 8:32 AM UTC

}// 134/140

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#julia set for c = −0.8 + 0.156i

Show more comments…
u/pavel

Using x*y<n instead of the normal n&&x*x+y*y<2 is much shorter and creates the black whisps that look pretty cool.
u/pavel

This version makes it easy to play with different values of c. You can find some in https://en.wikipedia.org/wiki/Julia_set#Quad…
u/pavel

https://en.wikipedia.org/wiki/Julia_set#Quad…
u/pavel

Is link pasting broken?
u/Xen

Sexy!
u/katkip

wow
u/katkip

https://en.wikipedia.org/wiki/Julia_set
u/rodrigo.siqueira

Awesome and fast. I am remixing it to add color schemes and colorization methods.
u/Qwitter

SO FAST!

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pavel

function u(t) {

for(let i=1920,f=(x,n=420,a=0,b=0)=>a*a+b*b<n?f(x,n-1,a*a-b*b+x,2*a*b+.1133-t/4615):n/420;i--;)x.fillRect(i,180*t,f(i/8e5-.7467),3)

Apr 18 2020 5:59 AM UTC

}// 131/140

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(X=-0.7453, Y=0.1127, R=6.5e-4) section of the #mandelbrot set

u/pavel

This version draws 1x3 pixels to speed up rendering. for(let i=2e3,f=(x,n=420,a=0,b=0)=>a*a+b*b<n?f(x,n-1,a*a-b*b+x,2*a*b+.1133-t/13845):n/420;i--;)x.fillRect(i,60*t,s=f(i/8e5-.7467),s) looks better in fullscreen but is 3x as slow.
u/pavel

let and the automatic scoping of args in f makes this _really_ quick. I can increase the loop to 4e3 iterations and still have 60fps on my machine. Would be interesting to speed this up by rendering multiple rows per frame.
u/katkip

all dweets made by u/pavel are genius
u/Xen

godlike!
u/Qwitter

agreed !!!!

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pavel

remix of d/12336 by u/pavel

function u(t) {

for(i=t?w=600:a=b=0;i--;x.fillRect(w*b,w-w*a,1,1))[a,b]=[[3.4*a+b/6,a-b,b-a,0][q=Math.random()**t*4|0]/4,[3.4*b-a/6+2,a+b+1,a+b+.5,b][q]/4]

Apr 17 2020 11:24 PM UTC

}// 139/140

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Barnsley #fern #fractal #leaf #uncompressed

u/pavel

This version is also #improved with a #grow effect and a cap on how dark the image gets if you leave it for a while.
u/Xen

nice!

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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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rodrigo.siqueira

remix of d/18262 by u/KilledByAPixel

function u(t) {

c.style.filter=`sepia()invert(`
for(P=j=2e4;j--;j%99||(T=P=S(t+j)*2,R=C=T*2))
P=P*P-C*C+(C=2*C*P+R,T),x.fillRect(C*450+960,P*450+700,1,1)

Apr 15 2020 12:59 AM UTC

}// 137/140

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Particle collision inside a hadron collider #particles

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doughno

function u(t) {

w=1920
h=1080
for(i=0;i<16;i++){
x.fillStyle=i%2?"#000":"#FFF"
s=(350+i*40)*C(t*1.5)-i*100
a=s+600
if(a>0)
x.fillRect((w-a)/2,(h-a)/2,a,a)
}

Apr 15 2020 12:54 AM UTC

}// 140/140

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u/sigveseb

Sweet
u/Xen

nice!

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BriSeven

function u(t) {

eval(unescape(escape`挮睩摴桼㵮㴶㐻景爨樽渻樭ⴻ⥦潲⡩㵮㭩ⴭ㭸⹦楬汒散琨ⴲ㔬㠰⭃⡡⨴⵴⨴〩⨳〭䌨㌪樯渫㤩⨵〬㈰ⰲ〩⥸⹦楬汓瑹汥㵒⠲㔵⵪⨳ⱪ⤬砮獥瑔牡湳景牭⡃⡡㴶⸲㠪椯渫琩⨲ⱓ⡡⤬ⵓ⡡⤪㈬䌨愩ⰹ㔰ⰵ〰⭪⨷⤠`.replace(/u(..)/g,"$1%")))

Apr 14 2020 11:28 AM UTC

}// 139/140

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A tasty bella pepper.

u/sigveseb

Mmm makes me hungry
u/BriSeven

Ages ago I had a super long dweet that I couldn't post, that was something like 3d lighted aliens made from randomized particles. The trickiest thing about them was the z-sorting. But, you kinda get that for free if you carefully draw in layers along the axis you're rotating on. Painter's algorithm in essence, but the data is structured so you don't have to run a sort.
u/BriSeven

one of these days I'll understand the BSP algorithm

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KilledByAPixel

remix of d/18243 by u/KilledByAPixel

function u(t) {

eval(unescape(escape`𩡯𬠨𪠽𝀸𛁺🐵𝀰𞱪𛐭𞰩𩡯𬠨𪐽𜡥𜰬𠐽𥀨𠠽𥀨𥀽𣑡𭁨𛡲𨑮𩁯𫐩𚠴𛐲𚐪𜰭𜠬𦀽𠐬𦐽𠠻𦀪𪐭𛐻𮀮𩡩𫁬𤡥𨱴𚁴🰸𜀰𛑘𚡺𞠰𛁴🱙𚡺𚰵𝀰𞠰𛁗👴🰨𮀮𩡩𫁬𤱴𮑬𩐽𨁨𬱬𚀤𮱩𛰳𯐬𞐹𙐬𙁻𞐹𛑩𛰳𞑽𙐬𜑠𛀱𚐺𜡥𜰬𥰩𚑘👘𚡘𛑙𚡙𚰨𦐽𜠪𦀪𦐫𠠬𠐩`.replace(/u../g,'')))

Apr 12 2020 6:34 AM UTC

}// 139/140

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Mandlebrot Nebula 2.0

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KilledByAPixel

remix of d/18218 by u/KilledByAPixel

function u(t) {

eval(unescape(escape`𩡯𬠨𪐽𞐻𪐭𛐻𨐮𫑡𬀨𫰽🡻𭱩𭁨𚁯𚑘𙠦𮀮𨱬𩑡𬡒𩑣𭀨𚁘👘𚡘𛑙𚡙𚰨𦐽𜠪𦐪𦀫𠠬𠐩𚐪𝐴𜀫𜐲𜀰𛁙𚠵𝀰𚰵𝀰𛀵𛀵𚑽𚐩𮀮𩡩𫁬𤡥𨱴𚀰𛀰𛀲𩐳𛀲𩐳𚐬𭀿𨐮𬁵𬱨𚁻𦀺𠐽𥀨𥀽𣑡𭁨𛡲𨑮𩁯𫐩𚠴𛐲𛁙𞡂👔𚁸𛡧𫁯𨡡𫁁𫁰𪁡🐮𜀳𚐪𜰭𜠬𠐬𠡽𚐺𨐽𦱝`.replace(/u../g,'')))

Apr 12 2020 5:10 AM UTC

}// 140/140

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Capturing Mandelbrot Orbits

u/rep_movsd

These are attracting me strangely :p
u/KilledByAPixel

#buddhabrot #fractal

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pavel

remix of d/13495 by u/pavel

function u(t) {

for(i=t?c.width|=C=_=>u[j=q+n&-n|p/n]=-!u[j]|1:p=q=r=s=571;i--;u[i]||x.fillRect(i?i%n*n:p+=r*=C(p+=r),i?i&-n:q+=s*=C(q+=s),z=i?n:15,-z))n=64

Apr 11 2020 10:31 PM UTC

}// 140/140

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#breakout

Show more comments…
u/pavel

Fixed the tilted look, the missing upper left block, and increased the size of the ball.
u/pavel

Why does changing 571 break the code for most values? :)
u/pavel

472, 582, 593 work well though
u/iznax

The code seems to work with most starting values if you change it to "C=_=>(p|q)<0?-1:u[j=q+n&-n|p/n]=-!u[j]|1" and handle negative coordinates as blockers?
u/KilledByAPixel

👍
u/pavel

Its shorter to init positions and velocities to same number but makes velocities too fast. Another problem is that init needs to happen once and shortest way to do that is t?<spot>:init which creates a spot to do something every non-first frame. I solve both problems by naming my collision detection function C and defining it on every non-first frame. On the first frame C is Math.cos so the velocity update code does r = r*C(p+=r) = 571*Math.cos(571+571) = 17.7 which is a reasonable speed.
u/pavel

The ball needs to be updated once per frame. Since I am iterating with a single index its easiest to check for index 0. This corresponds to the upper left block which is why it was missing in the original. A short fix is to shift everything up one block by using negative height for the blocks and adding a row to ball position encoding. The +n in q+n&-n|p/n.
u/pavel

I encode and decode 2d co-ordinates into one number. The block coordinates are (i%n,i/n|0) and their width is n making their real positions (i%n*n,(i/n|0)*n). Lets simplify the second one. If we choose n=2**k then (i/n|0)*n = (i/2**k|0)*2**k = (i>>k)<<k so we are zeroing out the last k binary digits. But if n=2**k then -n is a bunch of ones followed by k zeroes (https://en.wikipedia.org/wiki/Two%27s_comple…)! Therefore (i/n|0)*n = i&-n.
u/pavel

Need to check if ball pos (p,q) touches a new block. Ball is always in some block, find that blocks pos index. Dividing ball position by n gives the virtual coords and blocks are 1x1 so truncating gives 2d block coordinates (p/n|0,q/n|0). Want to encode this into index j where (x,y)=(j%n,j/n|0). Therefore j=(q/n|0)*n+(p/n|0). If n=2**k then in binary j=[32-k binary digits y-coord][k binary digits of x-coord] so we can use bitwise-or which also auto-truncates so j=(q/n|0)*n|p/n. And as we saw (q/n|0)*n=q&-n so j=q&-n|p/n! Real code uses j=q+n&-n|p/n to add one row to ball pos to account for shift up to hide missing (0,0)` block.
u/pavel

p+=r*=C(p+=r) encodes an unbelievable trick that is perfect for collision detection. For detection we need to independently try advancing vertically and horizontally, check for collision, and reverse course if hit. The temporary state involved in trying can cost a lot of chars. p+=r*=C(p+=r) does it all and C doesn't even read its argument! When C is invoked the global p it sees was already incremented by r. However, the outer p+= will eventually discard that increment. Magic!
u/rep_movsd

Un-effing-believable
u/hvianna

Wow, this is insane!
u/jylikangas

Masterclass in code golfing!
u/13thptr

awesome, looks like the ball escapes without breaking everything after a while though. will read the explanation more thoroughly.
u/pavel

No chars left for bounds checks! It freaks out with negative positions. If I find a way to shorten I will add bounds.
u/ersagun

I need to read and reread that explanation on a loop until I get this. This is incredible.
u/Qwitter

Just wow.

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