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Make it flash ⚡️ in HTML Canvas

soorajsnblaze333 profile image Sooraj ・2 min read

Hey guys, after the Make it Rain with HTML Canvas, I am back with another fun canvas experiment. This time I created flashes of lightning using the line method of canvas. The creativity of canvas is unlimited and it's up to you to explore the possibilities.

(If pen doesn't run or is windowed, please click re-run. Sometimes there is an issue where the pen doesn't run.)

I just used the same concept when we draw a squiggly line on a piece of paper.

  • Draw a line.
  • Use the ending point of the previous line as the start of the next line.
  • Keep repeating this.

You can check out the code in the codepen above.

I added this configuration to play around with the types of bolts generated.

const interval = 3000;
const lightningStrikeOffset = 5;
const lightningStrikeLength = 100;
const lightningBoltLength = 5;
const lightningThickness = 4;
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interval - creates a lightning strike after the specified milliseconds
lightningStrikeOffset - determines how angled each bolt is. The more the offset, the more slanted the bolts look. I found 5 to be a good enough value.
lightningStrikeLength - determines how many bolts the strike will have.
lightningBoltLength - determines the length of a single line.
lightningThickness - determines the thickness of each line.

For the fade effect, I am just looping through the bolt and decreasing the opacity and thickness of the bolt.

for (let i = 0 ; i < lightning.length ; i++) {
  lightning[i].opacity -= 0.01;
  lightning[i].thickness -= 0.05;
  if (lightning[i].thickness <= 2) {
    lightning[i].end.y -= 0.05;
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Discussion (2)

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andrewbaisden profile image
Andrew Baisden

Pretty cool. I read the title though "Make it flash" and I was worried that you found some crazy hacky way to combine Adobe Flash with HTML5 canvas 🤣

soorajsnblaze333 profile image
Sooraj Author

Thanks :). Oops sorry for that. My last post on canvas was "Make it Rain" and the word that was catchy for this one was "Flash", So I used it for this.