Dweets awesomed by u/plusright

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: #ScaryMovies

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pavel

function u(t) {

with(x)for(c.width|=j=32,translate(960,r=540),h=355/226;j--;scale(s=1/2**.5/S(t/9%h+h/2),s))rect(-r,-r,2*r,2*r),rotate(t/9);x.fill`evenodd`

Sep 25 2020 6:19 PM UTC

}// 139/140

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Squares all the way down

u/pavel

Inspired my Matts shirt in https://youtu.be/Z4oy6mnkyW4
u/anotherkitten

reminds me of this album's cover https://en.wikipedia.org/wiki/Good_%26_Evil_…

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rodrigo.siqueira

remix of d/19334 by u/rodrigo.siqueira

function u(t) {

c.style.filter=`sepia(`
for(var i=5e3;i--;f(960,610,300,t*i))f=(X,Y,s,r)=>s>1?f(X-s*S(r),Y-s*C(r),s/2,C(t+i)-r*2):x.fillRect(X,Y,t<4,.5)

Jul 6 2020 2:00 AM UTC

}// 136/140

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Triple Convergence #symmetry

u/andrea270872

the 3d effect is great. it looks to me like an ancient broken vase! great

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pavel

remix of d/19060 by u/aaaaaz

function u(t) {

for(i=c.width|=0,x.scale(9,9);i--;)x.fillText(['✊🏻','✊🏼','✊🏽','✊🏾','✊🏿'][i%5],99+133*S(i*i),125-i/14+(7+i%7)*S(S(i)/5-2*t)**2)

Jun 6 2020 6:33 PM UTC

}// 126/140

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#blacklivesmatter

u/AndrewK

cool
u/albertmelo

beautiful!
u/aaaaaz

Thank you ^^

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pavel

remix of d/18610 by u/KilledByAPixel

function u(t) {

with(x)for(k=i=999;--i;beginPath(fill(arc(k+i+r*C(a=i%2?i+240*t:(i-k*t>>5)**5),540+r*S(a),r/5,0,7))))fillStyle=R(i/4),r=(S(t)/2+1+i%2)*7e4/i

May 7 2020 5:55 PM UTC

}// 140/140

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#blood #cavern 🩸 #uncompressed

u/KilledByAPixel

amazing!
u/KilledByAPixel

interesting how we made different concessions to make it fit!
u/katkip

now Hemoglobin is *l o n g e r* wow.
u/nml

looks like a red blood vessel

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pavel

function u(t) {

with(x)for(i=999;i--;fillRect(~setTransform(s=24e3/i,0,0,4*s,960-i+9*s*C(a=i+60*t),540+8*s*S(a)),~rotate(T(a*a)),2,2))fillStyle=R(9,i/4,i/3)

May 4 2020 7:34 PM UTC

}// 140/140

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Underwater #cavern

Show more comments…
u/KilledByAPixel

sick
u/KilledByAPixel

looped https://twitter.com/KilledByAPixel/status/12…
u/pavel

One trick here is f();g();h(-1,-1) is the same as h(~f(),~g()) when f and g return a falsy value, undefined in this case.
u/pavel

Notice how none of the distance variables are based on time, only angles are, yet the distances are changing and nothing is rotating...
u/pavel

Try making the moving a little faster :)
u/pavel

After I wrote this I looked for other dweets using a similar technique and this is the earliest one I've found, and it includes an explanation d/10212
u/KilledByAPixel

Amazing work! I have not seen the ~ before, will be using it a lot now. I tried to explain the 60*t trick in one of my blog posts, https://frankforce.com/?p=7160
u/pavel

That is an amazingly detailed explanation with great visual aids.
u/pavel

To clarify your explanation, any integer time works. 60*t is naturally an integer (ish). frame is one char longer without numerical errors. In general, (n*t|0) works for any n.
u/AndrewK

privet
u/katkip

masterpiece
u/joeytwiddle

I think this also counts as a #tunnel
u/Qwitter

Awesome!

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pavel

remix of d/11930 by u/pavel

function u(t) {

with(x)for(i=-6*t%1;i++<66;fill())for(beginPath(fillStyle=R(8*i,4*i),j=36);--j;arc(960,h+h*S(3*t)**2/i,h/i*(9+C(~~i+6*t^j)),b=9+j/9,b))h=777

May 2 2020 4:35 AM UTC

}// 140/140

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Walking through a #cavern

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u/KilledByAPixel

🤯 genius
u/KilledByAPixel

Looped! https://twitter.com/KilledByAPixel/status/12…
u/sigveseb

Wooow sweet!
u/aleamb

yeah!
u/sigveseb

Really nice colors
u/jick

Holy cow, wow!
u/Xen

sexy!
u/katkip

aannd we have a winner!
u/KilledByAPixel

https://www.reddit.com/r/perfectloops/commen…
u/pavel

the gif is very blurry
u/KilledByAPixel

HD gif for you - https://www.dropbox.com/s/u3wbakb6e4sm00y/pa…
u/Qwitter

Wow!
u/vain

Who needs longer shaders? ;-) Real DemoScene feeling

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pavel

function u(t) {

for(let i=2e3,f=(x,n,c=8-(t+6)*n)=>~n&(x*x*n*n+(8+(t-12)*n)**2+c*c-5)**2/16+c*c>1?f(x,n+=.002):c;i--;)x.fillRect(i,t*180,f(i/135-7,.7),3)

Apr 23 2020 7:27 AM UTC

}// 137/140

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Actually #raytracing a #torus using ray marching

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u/Xen

Sweeet!
u/tomxor

Yes! we need more explicit surfaces on dwitter :)
u/Odog8

which expression is the DFT?
u/tomxor

I'm confused... this isn't explicit? it recurses.
u/pavel

This recurses just to advance ray length.
u/pavel

The closed form expression is x*x*n*n+(8+(t-12)*n)**2+c*c-5)**2/16+c*c-1 where c=8-(t+6)*n and n is the free variable.
u/tomxor

Ah, so is this technically ray casting? I have to ask because I still don't intuitively get all of the math.
u/tomxor

Sorry I meant ray marching
u/pavel

Yes. The math constructs a ray from (0,8,8) looking at (0,0,0), varied a bit depending on the pixel being drawn, its length is a function of n. I plug this into the equation for a torus and increment n from .7 to -1 until I find a zero of the equation.
u/pavel

Here is a version without much golfing that makes things clearer for(let i=2e3,f=(o,n,x=o*n,y=t/3*n-n,z=4-n)=>z>-1&(x*x+y*y+z*z+3)**2>16*(x*x+y*y)?f(o,n+.01):z;i--;)x.fillRect(i,t*180,f(i/540-16/9,3),3)
u/pavel

(x*x+y*y+z*z+3)**2>16*(x*x+y*y) is directly from https://en.wikipedia.org/wiki/Torus
u/pavel

with R=2 and r=1
u/pavel

This example shoots rays from (0,0,4). In order to rotate the shape you have to move where the rays come from, the camera!
u/tomxor

Thanks for the explanation 👍

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pavel

function u(t) {

for(c.width=i=640,n=32,q=2*t%1*n|0;i--;x[X>7&X<12&[810,865,1858,9808][q>>3]>>i/8+X+6?'fillRect':'strokeRect'](X*n-q,(i&-n)-q,n,n))X=i%n

Apr 16 2020 7:25 PM UTC

}// 135/140

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Keep Gliding Mr Conway

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u/pavel

#gameoflife #glider
u/pavel

https://www.reddit.com/r/perfectloops/commen…
u/Xen

love it!
u/joeytwiddle

#tribute
u/rodrigo.siqueira

Wow! I've been using this Glider image (also known as HACKER EMBLEM) for years as my computer wallpaper, here is full hd version of my wallpaper: https://in.bot/agi/Hackers-emblem-Carbon-Gli…
u/Qwitter

Life was definitely a gateway drug for me as well.

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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

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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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f8f82804

remix of d/11809 by u/f8f82804

function u(t) {

throw s=t?s.replace(/[\u0300-\u0312]*/g,
m=>m.slice(-64)+String.fromCharCode(768
+18*Math.random())):' '.repeat(512)

Jan 15 2019 9:00 PM UTC

}// 116/140

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#zalgo #unicode #glitch #corruption #matrix #waterfall #throw #regex #regexp #golf

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