Dweets awesomed by u/vovanmozg

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: #Opposites

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BriSeven

remix of d/18263 by u/BriSeven

function u(t) {

eval(unescape(escape`挮睩摴桼㵮㴱㘻⁦潲⡫㵮⩮㭫ⴭⱩ㵫╮ⱪ㵫⽮簰㭸⹦楬汒散琨㄰〭㠰⨨椥㐩ⰱ〰⴨椯㑼〩⨸〬㐰ⰴ〩⥸⹦楬汓瑹汥㵠桳氨〬〥Ⱔ笸〭横㕽╠ⱸ⹳整呲慮獦潲洨䌨愽琩⨲ⱳ㵓⡡⤬⵳⨲ⱃ⡡⤬㤵〬㔰〫横㜩`.replace(/u(..)/g,"$1%")))

Apr 26 2020 12:07 PM UTC

}// 136/140

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Almost a procgen city but not quite enough room.

u/BriSeven

#cube
u/tomxor

I like where this is going :)

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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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pavel

function u(t) {

for(c.width=i=620;i--;x.lineTo(310*(z+p*S(b))/z,300*(3+q*C(a))/z))q=i/8&1||-1,p=4-q*S(a=S(a=S(b=i/98+2*t)+b)/2+a/2),z=8+p*C(b-=t);x.stroke()

Apr 4 2020 7:12 PM UTC

}// 140/140

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#mobius strip

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u/pavel

Using sin(sin(x)+x)+sin(x)+x as a smooth staircase function to implement the flip as a pulse.
u/KilledByAPixel

👍
u/Xen

love it
u/aleamb

love it!
u/danny@hille.dk

Nice - möbius tape
u/Qwitter

Im sorry, but I find only one side of this to be Awesome.
u/vain

beautiful and smooth transformation / animation

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pavel

function u(t) {

for(i=1920;i--;x.fillRect(i&-T,i%T*T,T=32,T))x.fillStyle=`hsl(${T*t},99%,${u[i]=u[i]*.94+T/Math.hypot(i/T-T-C(3*t)*20,i%T-16-S(4*t)*9)||0}%`

Apr 2 2020 4:46 AM UTC

}// 140/140

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Flare

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u/pavel

Inspired by https://twitter.com/ntsutae/status/124366720…
u/jylikangas

Lovely use of an array for the trail effect!
u/BriSeven

hypot?! WHAAAT how long has THAT been there?
u/katkip

this is actually easier than it looks
u/sigveseb

Looks very pretty :)
u/aleamb

amazing!
u/rodrigo.siqueira

It reminds me the light and movement of this Fluid Simulation https://paveldogreat.github.io/WebGL-Fluid-S…
u/Scaledish

hell, it looks better than the fluid simulation
u/joeytwiddle

#glow #worm

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xem

function u(t) {

c.width=40;for(i of["pixelated","crisp-edges"])c.style.imageRendering=i;x.font="16px a";x.fillText(String.fromCodePoint(127744+t*5|0),0,16)

Mar 27 2020 4:42 PM UTC

}// 139/140

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Experiment: show every emoxi as a 16*16px sprite with crisp edges (Fixed for Fx & Chrome)

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pavel

function u(t) {

for(i=c.width|=0;j=--i>>5;x.fillRect(960*(z+S(j*j)+r*C(i))/z,3e3*(.2+m*(m<0&&-1)**i)/z,s=--m*9/z,s))m=(t+j/7)%2-1,r=m>0&&m/3,z=2+S(j)+r*S(i)

Mar 25 2020 8:28 AM UTC

}// 140/140

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Reflections on #rain

u/katkip

beautiful
u/aleamb

amazing
u/vain

amazing rain drop fx

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pavel

remix of d/17888 by u/New_Core

function u(t) {

for(k=c.width|=0;j=--k>>6;x.fillRect(960+99*(2*C(j)+S(i*22))/z,540+(99*S(j)+i*S(v=i/69)*C(v-5*q))/z,4/z,8*S(4*v-4)/z))i=k%64,q=t+j,z=5-q/3%5

Mar 11 2020 7:08 PM UTC

}// 140/140

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Birds 2

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pavel

function u(t) {

for(c.width|=j=21,x.scale(5,5),x.lineJoin="round";j--;)for(i=26;i--;)x.arc(192,108,1.3**(r=j+i%2+t%2),a=(i+j)%24/3.8197+C(r)/2,a);x.stroke()

Feb 11 2020 7:29 AM UTC

}// 140/140

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Creeping

u/katkip

kind #tunnel
u/Yogeshp3

source of mathematics?
u/cantelope

source: pavel
u/pavel

I was inspired by https://twitter.com/beesandbombs/status/1221… I wanted to see if I could draw it with one stroke. Then I just started playing around. +C(r)/2 does most of the work here, if you delete it you can see the reference shape.
u/pavel

%24 is only there to avoid a bug in Safari from angle being too big on arc. /3.8197 is short for *Math.PI/12

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pavel

function u(t) {

X=450
c.width|=f=(r,a,o)=>r>9?f(r/=2,a-o,-o)+f(r,a,o)+f(r,a+o,-o):(t-=.02)>0&&x.lineTo(X+=r*C(a*=355/339),Y+=r*S(a))
f(Y=1e3,0,1)
x.stroke()

Jan 17 2020 3:27 AM UTC

}// 140/140

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One stroke #sierpinski

u/tylertoomey

Wow, this is phenomenal!
u/katkip

#curve #sfcurve

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pavel

remix of d/16909 by u/rodrigo.siqueira

function u(t) {

for(x.fillRect(x.globalAlpha=.1,0,i=2e3,i);r=--i*S(t/3);x.clearRect(960+r*S(a)*C(i)/z,540-r*S(i)/z,s=z>0&&6/z,s))z=1+r/2e3*C(a=i*i+t/9)*C(i)

Dec 19 2019 11:08 PM UTC

}// 140/140

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#stars #explosion

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