Dweets awesomed by u/baon

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) {

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

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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/18577 by u/trusktr

function u(t) {

c.parentNode.style='perspective:4in';onmousemove=e=>c.style=`background:tan;transform:rotateY(${e.x-284}deg)rotateX(${160-e.y}deg)scale(.7)`

May 3 2020 2:29 AM UTC

}// 140/140

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Tan plane looking at your mouse

u/pavel

#interactive #mouse
u/pavel

I tried doing this in js but its just too hard to fit!
u/pavel

168 c.width|=onmousemove=e=>T=e;b=.6-T.y/264;e=g=>C(i)*g(1-T.x/264);f=g=>S(i)*g(b)+e(S)*g(b-1.6);for(i=.8;i<6;x.fill(x.lineTo(960+e(C)/z,540-f(C)/z)))i+=1.57,z=(2+f(S))/960
u/pavel

This post looks better with rotation angles divided by 2 but I couldn't figure out how to fit it.

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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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lionleaf

remix of d/41 by u/lionleaf

function u(t) {

c.width=2e3;x.lineWidth=9;for(i=0;s=300,a=s/(s-(t+i*s/400)%s),i<400;i++){x.strokeRect(999-a*(1+S(t))/2,500-a*(1+C(t*2))/2,a,a)}

May 1 2020 9:47 PM UTC

}// 127/140

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Basic #cavern #tunnel but missing some organic texture

u/WasifBoomz

This could make for a fun game!
u/lionleaf

test
u/lionleaf

test

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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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lionleaf

remix of d/18375 by u/sigveseb

function u(t) {

r=Math.random
for(i=899;i--;)R=r()*300,A=r()*6.28,x.fillRect(960+R*S(A),540+R*C(A),3,3)

Apr 21 2020 8:56 PM UTC

}// 87/140

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#circlechallenge - try changing the 6.28 to 6, 7 or 8 :)

u/donbright

i change it to t ;)

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New_Core

function u(t) {

c.style.filter=`blur(${30-30*S(t)}px)contrast(99)`
x.fillRect(620,240,680,600)

Apr 21 2020 1:33 PM UTC

}// 78/140

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with cutting edge technology #circlechallenge

u/New_Core

${5-5*S(t)}vw for the blur works better for fullscreen also..
u/lionleaf

Haha, love the pun

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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(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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