Dweets awesomed by u/jylikangas

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

function u(t) {

for(let j=3,X,r,f=x=>S(16*x)**420;j--;)for(let Y=t/3+j/540-1,i=2e3;i--;x.fillRect(i,t*180+j,2*r,f(X/r)+f(Y/r)))X=i/540-16/9,r=X*X+Y*Y

Apr 23 2020 5:31 AM UTC

}// 133/140

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Conformal mapping of a grid (1/z), all intersections are at right angles

u/pavel

Set r=1 to see the grid.

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pavel

function u(t) {

for(f=c=>Math.tanh((r>1?3:13)*S(9*c/d)),Y=t/3-1,i=2e3;i--;x.fillRect(i,t*180,(1+f(X)*f(Y))*(d/2+Y/3.6),3))X=i/540-16/9,r=X*X+Y*Y,d=r>1||C(r)

Apr 22 2020 6:18 AM UTC

}// 140/140

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Experimenting with #raytracing. I finally figured out why the cosine trick from d/1112 works.

u/Cloud

WOW!

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ersagun

remix of d/18372 by u/KilledByAPixel

function u(t) {

x.fillRect(960-t*200,540-(w=(t*(2-t))**.5*200),4,w*2)

Apr 21 2020 6:59 PM UTC

}// 53/140

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Is this ok?

u/BriSeven

#circlechallenge

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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

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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KilledByAPixel

function u(t) {

c.style.filter='sepia()invert('
r=Math.random
A=X=r()*4-2
B=Y=r()*2-1
for(q=i=540;i--;x.fillRect(X*q+1200,Y*q+q,1,1))X=X*X-Y*Y+(Y=2*Y*X+B,A)

Apr 9 2020 4:39 AM UTC

}// 140/140

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Mandelbrot Galaxy #Fractal #SlowDraw

Show more comments…
u/KilledByAPixel

GIF: https://twitter.com/KilledByAPixel/status/12…
u/KilledByAPixel

#Mandelbrot #WaitForIt
u/joeytwiddle

Very pretty! Mandelbrot in space
u/iverjo

Impressive
u/tomxor

Incredible!
u/aleamb

beautiful!!
u/Xen

sexy!
u/DataMeta

coool!
u/KilledByAPixel

thank you 😊
u/KilledByAPixel

#buddhabrot
u/Qwitter

Nice to see

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pavel

remix of d/18153 by u/Kirjava

function u(t) {

with(x)for(beginPath([X,Y=X,r=200,a=2]=u[T=-~T]||[999]),fillStyle=R(i=4,3e3/r);i--;fill())lineTo(...u[2*T+i]=[X-C(--a)*r,Y+S(a)*r,r*.8,a-9])

Apr 7 2020 3:38 AM UTC

}// 140/140

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#tree #waitforit #uncompressed

u/pavel

This is a breadth-first traversal of a binary tree, one frame at a time. The tree is maintained in a 1D array (2n+i notation) that I simply iterate left-to-right. The loop does double-duty for drawing the current node and inserting the children. The shape has four corners so the loop runs four times and inserts four children: 2n+0, 2n+1, 2n+2, 2n+3. My mind was blown when I realized no extra code was needed to prevent the adding of the extra children because the first two children of the next iteration will overwrite them!
u/joeytwiddle

#broccoli
u/katkip

interesting
u/pavel

https://i.imgur.com/FZ9Whj4.png

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Kirjava

function u(t) {

eval(unescape(escape`𭱩𭁨𚁸𚐨𩀽𚁛𫀬𩑝𛁦𛁮𛁯𚐽🡻𪑦𚁯🀹𚑻𩡯𬠨𬀽𦱢𩑧𪑮𤁡𭁨𚁦𪑬𫁓𭁹𫁥🐢𘰱𘠫𫰫𜀩𧐬𪐽𝀻𪐭𛐻𚑬𪑮𩑔𫰨𛠮𛡰𦱩𙐲𧐽𦱬𚱓𚁣👩𚱮𚐪𩠬𩐫𠰨𨰩𚡦𧐩𞱦𪑬𫀨𚐬𬀮𫑡𬀨𚁩𛁬𚐽🡤𚁩𛀮𞀪𩠬𫠪𚁬🰱𛠱𞠮𞀩𛁯𚰱𚐩𯑽𚐨𦰱𩐳𛀱𩐳𧐬𜠴𜀬𜠮𝰬𜀩`.replace(/u../g,'')))

Apr 5 2020 11:47 PM UTC

}// 140/140

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#tree

u/96W

beautiful!

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