Multi #langton's #ant by tomxor

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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tomxor

remix of d/21783 by u/tomxor

function u(t) {

A=t?A.map(a=>(s=u[a>>4]^=1,x[s?'fillRect':'clearRect'](a>>6,a&1008,16,16),a=a+2*s+1&~4,a+=a&1?a%4-2<<10:a%4-1<<4)):[54675,69010,69233,54896]

Mar 2 2021 11:27 PM UTC

}// 140/140

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Multi #langton's #ant

u/tomxor

Squashed each ant into a 16bit bit field, [X,Y,D] = 0b 111111 111111 0111. These ants were generated with: X=7,Y=7,D=0,[[-X,-Y,3+D],[+Y,-X,2+D],[+X,+Y,1+D],[-Y,+X,0+D]].map(([X,Y,D])=>X+60<<10|Y+32<<4|D%4<<0)
u/mark1626

This is incredible. Just one question, how does s = u[a >> 4] ^= 1 work?
u/tomxor

Thanks :) a>>4 is the cell index of a 64x64 grid. the lower 4 bits are for the ant's direction so shifting them off to the right leaves only the 12 X and Y bits (see above). u is just an object, so all of these indicies will be undefined initially, but undefined is falsey and bitwise operators coerce falsey into 0, i.e undefined ^ 1 == 0 ^ 1 == 1, in otherwords XOR just treats all of the initial cell values as 0. Using the assignment version ^= means we toggle each cell between 0 and 1 each time an ant passes through it (which is part of the langton ant rules).


      u(t) is called 60 times per second.
      t: elapsed time in seconds.
      c: A 1920x1080 canvas.
      x: A 2D context for that canvas.
      S: Math.sin
      C: Math.cos
      T: Math.tan
      R: Generates rgba-strings, ex.: R(255, 255, 255, 0.5)

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