Dweets awesomed by u/BackendForth

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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rodrigo.siqueira

remix of d/18458 by u/rodrigo.siqueira

function u(t) {

for(X=f=c=>S(S(9*c/d)*t),Y=t/8-1.1,i=2e3;i--;x.fillRect(i,t*60,(1+f(X=i/480-2)*f(Y))*(d/2+Y),3))x.fillStyle=R(C(r=X*X+Y*Y)*125),d=r>1||T(r)

Apr 23 2020 5:58 PM UTC

}// 139/140

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Red Sphere Reflection #raytracing (high resoluton)

Show more comments…
u/Xen

Tf Dude! top dweet right here 😍
u/lionleaf

That's amazing!
u/lionleaf

#glass #sphere
u/stiaje

#witchcraft
u/Ath0r

Impressive, great job!
u/katkip

genius script
u/PoweredByWill

wow. dwitter povray.
u/mole

I am shooketh. This is absolutely incredible.
u/katkip

#slowrender
u/cli

This is great.
u/Nascretis

Actually insane. #witchcraft

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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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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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katkip

function u(t) {

eval(unescape(escape`𨰮𬱴𮑬𩐮𩡩𫁴𩑲🐧𨡬𭑲𚀴𬁸𚑣𫱮𭁲𨑳𭀨𞐹𚐧𞱴𯁼𮀮𭁲𨑮𬱬𨑴𩐨𞐶𜀬𝐴𜀩𞱸𛡲𫱴𨑴𩐨𜠮𜀹𚐻𮀮𩡩𫁬𤡥𨱴𚀰𛀰𛀵𜀬𞐹𞐩𛁸𛡦𪑬𫁓𭁹𫁥👠𪁳𫀨𙁻𚁴𯀰𚐪𞐰𯐠𞀹𙐳𜀥𚑠𞱸𛡤𬡡𭱉𫑡𩱥𚁣𛀰𛀰𛀲𩐳𛀱𩐳𚐠`.replace(/uD./g,''))) // trippy O-O

Mar 17 2020 2:44 PM UTC

}// 140/140

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#compressed #trippy

u/sigveseb

Nice!

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tomxor

remix of d/17835 by u/pavel

function u(t) {

eval(unescape(escape`𫱮𫑯𭑳𩑭𫱶𩐽𩐽🡦𚁸𛡬𪑮𩑗𪑤𭁨🐴𛀴𛁣𛡷𪑤𭁨👩𫡮𩑲𥱩𩁴𪀬𤠽𩐩𒡦🐨𦀬𦐬𭰩🐾𚁒𛡸𛑘𛑷𛰲𚐪𚠲𚰨𤠮𮐭𦐭𭰯𜠩𚠪𜠼𭰪𭰪𝠮𜠸𚰳𩐴🱷🠶𙠦𩠨𦀬𦐬𭰯🐲𚑼𩠨𦀫𭰬𦐬𭰩𯁦𚁘𛁙𚱷𛁷𚑼𩠨𦀫𭰬𦐫𭰬𭰩𞡸𛡳𭁲𫱫𩑒𩑣𭀨𦀬𦐬𭰬𭰩`.replace(/u../g,'')))

Mar 5 2020 2:17 AM UTC

}// 135/140

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#interactive #quadtree (move your mouse)

u/tomxor

Note the intersection is fuzzy since full circle-AABB takes too much code, instead it's just circle-point + current subdivision width based radius (w*w*6.28), i.e it becomes more accurate as it converges.
u/tomxor

This is why there are a bunch of divisions around it that would not exist with an exact test. Pavel's doesn't do this by cleverly choosing a geometry that only need intersect the top left of each square.
u/katkip

Nice!

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pavel

function u(t) {

c.width|=f=(X,Y,w)=>X*X+Y*Y<=2e6*S(t/9)**2?w>9&&f(X,Y,w/=2)|f(X+w,Y,w)|f(X,Y+w,w)|f(X+w,Y+w,w):x.strokeRect(X,Y,w,w);f(x.lineWidth=4,4,1072)

Mar 4 2020 5:31 AM UTC

}// 140/140

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Quadtree

Show more comments…
u/katkip

Awesome!
u/tomxor

I love it !
u/sigveseb

Cool!
u/Xen

SEXY!
u/aleamb

love it!
u/tomxor

#Quadtree
u/Qwitter

YES!!
u/vain

Never saw this fx before. But it looks really beautiful

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Xen

remix of d/17803 by u/Xen

function u(t) {

with(x)t?fillRect(C(S(t*8))*90-99,t*199,699,9,fillStyle=R(z)):fillRect(!fillRect(0,0,z=2e3,z,fillStyle="#00a"),800,z,z,fillStyle="#ff0")

Mar 3 2020 4:46 PM UTC

}// 136/140

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#Sonic Level Transition: Sonic2

u/RealPeha

It would seem, what does Ukraine have to do with it?
u/cowberry

Ukrainr -> Belarus 30%
u/cowberry

*Ukraine

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KilledByAPixel

function u(t) {

eval(unescape(escape`𭱩𭁨𚁸𚑦𫱲𚁣𛡷𪑤𭁨𯀽𪐽𜠻𪐭𛐻𨱬𪑰𚁳𭁲𫱫𩐨𚐩𚑦𫱮𭀽𚀱𝀭𪐪𞐩𚰧𩑭𘠧𛁦𪑬𫁔𩑸𭀨𙱍𨑧𫡩𩡹𪑮𩰠𡱬𨑳𬰧𛀶𞐰𛐡𪐪𚁺🐵𝀰𛑃𚁴𚐪𝀸𜀩𛀵𝰰𚰡𪐪𜰰𚐬𮁛𩠽𙱦𪑬𫁓𭁹𫁥𙱝🐧𘱆𡡆𙰬𮁛𩡝👒𚀡𪑼𯁦𪑬𫀨𨑲𨰨𝰲𜀫𮠯𜠬𝐴𜀬𜠵𜀬𜀬𝰩𚐩`.replace(/u../g,'')))

Mar 2 2020 7:20 PM UTC

}// 139/140

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Magnifying #Glass 🔍

u/lionleaf

Clever!
u/katkip

good idea

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rodrigo.siqueira

remix of d/15411 by u/rodrigo.siqueira

function u(t) {

c.width|=v=(a,b,Φ,r)=>{for(i=~r;i++;)x.fillRect(a-=S(Φ),b-=C(Φ),s=r/9,s)
r>15&&v(a,b,Φ-S(t),r*=.5)&v(a,b,Φ+C(r-t),r*=1.6)}
v(940,1e3,0,230)

Feb 29 2020 3:38 PM UTC

}// 139/140

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Dancing branches #organic #tree #growth

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KilledByAPixel

remix of d/17468 by u/KilledByAPixel

function u(t) {

eval(unescape(escape`𚰫𭀥𝀾𜐿𥀽𧰽🡓𚀫𚱴𚡴𚐺𣰽𦱻𦀺𭀪𜰰𙐱𞀵𜀫𝀹𛁙𞡴𚠲𚰱𝠹𛁡𞠰𛁢𞠰𯑝𒡦𫱲𚁯𘁯𩠠𣰩𨠽𚰫𫰮𨠬𨠽🐲𯁔𚀩🠮𞐹𞐹𞐶🱏𛡰𭑳𪀨𮱘𞡯𛡘𛑓𚁡👯𛡡𚐬𦐺𫰮𦐭𠰨𨐩𛁡𞡡𚠮𞐷𚰨𨠭𜠿𜐺𛠲𚐪𥀨𚐬𨠺𜁽𚐺𜀬𮀮𩡩𫁬𤡥𨱴𚁯𛡘𛁯𛡙𛁱👢𚠪𛠸𛰸𛁱𚐻`.replace(/u../g,'')))

Feb 11 2020 7:48 PM UTC

}// 140/140

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Tree Farm #growth

dwitter.net | BackendForth (17532)