#FDTD #Electromagnetic Sim - Rendering … 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

function u(t) {

eval(unescape(escape`𩡯𬠨𥁛𜐶𜀰𧐫👓𚁴𚠹𚐬𨰮𭱩𩁴𪀽𭰽𜐲𞀬𪐽𜑥𝀻𪐭𛐻𮀮𩡩𫁬𤡥𨱴𚁩𙑷𛁩🠾𝰬𜐬𜐩𚑕👵𛁵👔𦱩𧐽𥁛𪑝𚰨𠱛𪑝𛑃𦱩𛐱𧐭𤱛𪑝𚱓𦱩𛑷𧐩𛰱𝑼𯀰𛁸𛡦𪑬𫁓𭁹𫁥👒𚀳𜠰𚡍𨑴𪀮𪁹𬁯𭀨𭐪𚁓𦱩𧐽𤱛𪑝𛑔𦱩𚱷𧐫𭑼𯀰𚐬𭐪𚁃𦱩𧐽𠱛𪑝𚱕𛑵𯁼𜀩𚐩`.replace(/u../g,'')))

Mar 1 2026 1:51 AM UTC

}// 140/140

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#FDTD #Electromagnetic Sim - Rendering #Poynting Vector (EM Flux)

Show more comments…
u/tomxor

I don't really understand maxwell equations, I just wanted to see if I could fit an FDTD into a dweet, and the Poynting vector of the EM field flow looks kinda cool.
u/tomxor

It's essentially a 2D sim of a point oscillator in a reflective box (although technically left and right wrap around), it has absolutely no physical equivalence, all parameters are normalised and tuned for visual preference.
u/ximavus

basically waves bouncing in a box? This visualization is really good though
u/cantelope

oh. well if has no physical equivalence then...
u/tomxor

I just meant that it's more abstract, because FDTD is commonly used to simulate a particular thing in real life.
u/ximavus

yeah waves bouncing in a box is the only way I understand it its a lot more complex than that


      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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