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Cool Lightning Javascript Codepen

Fun!

I found a pretty cool codepen1 by jlong2 that makes neat Lightning bolts in a canvas.

Like I said in My Okkur Post I’m using hugo3 and this cool theme4 for the individual Lichtenberg art pieces5 skeleton website..
Each piece will have its’ own repo. which will include all the map files, and creation media for that piece.

I’ve tweaked the codepen to make it look more like lichtenberg art.
You can see that here6

You can view the gitlab pages render of it here7

The original version:

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# The main canvas and context.
canvas  = document.getElementById "canvas"
context = canvas.getContext "2d"

# The size and scale of the canvas. The size will get set via setCanvasSize to match the size of
# the window. Change the scale to get a more or less pixel-y effect.
width  = 0.0
height = 0.0
scale  = 1.0

# The frames per second of the simulation. We also keep track of the time the previous frame
# occurred so that we know the duration between each frame.
fps       = 45.0
lastFrame = (new Date).getTime()

# The screen will flash briefly when the flash opacity is set. The opacity will dissipate quickly
# over time.
flashOpacity = 0.0

# When a bolt appears, it will be drawn at full opacity for the flash duration, and then will fade
# out gradually over the fade duration.
boltFlashDuration = 0.25
boltFadeDuration  = 0.5
totalBoltDuration = boltFlashDuration + boltFadeDuration

# The list of bolts. A bolt will get added to this list on creation, and then will be automatically
# removed after it's done fading out.
bolts = []

# Sets the size of the canvas and each bolt canvas.
setCanvasSize = ->
	canvas.setAttribute "width",  window.innerWidth
	canvas.setAttribute "height", window.innerHeight
	
	for bolt in bolts
		bolt.canvas.width  = window.innerWidth
		bolt.canvas.height = window.innerHeight
	
	width  = Math.ceil window.innerWidth  / scale
	height = Math.ceil window.innerHeight / scale

# Launch a bolt!!!
launchBolt = (x, y, length, direction) ->
	# Set the flash opacity.
	flashOpacity = 0.15 + Math.random() * 0.2
	
	# Create the bolt canvas.
	boltCanvas        = document.createElement "canvas"
	boltCanvas.width  = window.innerWidth
	boltCanvas.height = window.innerHeight
	boltContext       = boltCanvas.getContext "2d"
	boltContext.scale scale, scale
	
	# Add the bolt to the list.
	bolts.push { canvas: boltCanvas, duration: 0.0 }
	
	# Launch it!!
	recursiveLaunchBolt x, y, length, direction, boltContext

# Recursive bolt action.
recursiveLaunchBolt = (x, y, length, direction, boltContext) ->
	originalDirection = direction
	
	# We draw the bolt incrementally to get a nice animated effect.
	boltInterval = setInterval (->
		if length <= 0
			clearInterval boltInterval
			return
		
		i = 0
		while i++ < Math.floor(45 / scale) and length > 0
			x1 = Math.floor x
			y1 = Math.floor y
			x += Math.cos direction
			y -= Math.sin direction
			length--
			
			if x1 != Math.floor(x) or y1 != Math.floor(y)
				alpha                 = Math.min 1.0, length / 350.0
				boltContext.fillStyle = "rgba(255, 255, 255, #{alpha})"
				boltContext.fillRect x1, y1, 1.0, 1.0
				
				direction = originalDirection + (-Math.PI / 8.0 + Math.random() * (Math.PI / 4.0))
				
				if Math.random() > 0.98
					recursiveLaunchBolt x1, y1, length * (0.3 + Math.random() * 0.4), originalDirection + (-Math.PI / 6.0 + Math.random() * (Math.PI / 3.0)), boltContext
				else if Math.random() > 0.95
					recursiveLaunchBolt x1, y1, length, originalDirection + (-Math.PI / 6.0 + Math.random() * (Math.PI / 3.0)), boltContext
					length = 0
		
		undefined
	), 10

# This will get fired at a constant framerate.
tick = ->
	# Keep track of the frame time.
	frame     = (new Date).getTime()
	elapsed   = (frame - lastFrame) / 1000.0
	lastFrame = frame
	
	# Clear the canvas.
	context.clearRect 0.0, 0.0, window.innerWidth, window.innerHeight
	
	# Fire a bolt every once in a while.
	if Math.random() > 0.98
		x      = Math.floor -10.0 + Math.random() * (width + 20.0)
		y      = Math.floor 5.0 + Math.random() * (height / 3.0)
		length = Math.floor height / 2.0 + Math.random() * (height / 3.0)
		
		launchBolt x, y, length, Math.PI * 3.0 / 2.0
	
	# Draw the flash.
	if flashOpacity > 0.0
		context.fillStyle = "rgba(255, 255, 255, #{flashOpacity})"
		context.fillRect 0.0, 0.0, window.innerWidth, window.innerHeight
		flashOpacity = Math.max 0.0, flashOpacity - 2.0 * elapsed
	
	# Draw each bolt.
	for bolt, i in bolts
		bolt.duration += elapsed
		
		if bolt.duration >= totalBoltDuration
			bolts.splice i, 1
			i--
			return
		
		context.globalAlpha = Math.max 0.0, Math.min(1.0, (totalBoltDuration - bolt.duration) / boltFadeDuration)
		context.drawImage bolt.canvas, 0.0, 0.0
	
	undefined

# Start it up!!!
window.addEventListener "resize", setCanvasSize
setCanvasSize()
setInterval tick, 1000.0 / fps

Lichtenberg coffeescript:

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# https://codepen.io/jlong64/pen/kXRxpA
# This expects to exist in an environment which has a background that's black. and has a canvas element named 'canvas'
# https://coffeescript-cookbook.github.io/chapters/math/generating-random-numbers
#
# The main canvas and context.
canvas  = document.getElementById "canvas"
context = canvas.getContext "2d"
boltCount=1
direction=0.00
lastLaunch=0
perSec=2000.0
maxBolts=9
boltAlphaMin=0.75
boltAlphaDivisor=200
maxBoltInterval=1
# The size and scale of the canvas. The size will get set via setCanvasSize to match the size of the window. Change the scale to get a more or less pixel-y effect.
width  = 0.0
height = 0.0
scale  = .50
#Set the starting point of bolts to the center of the frame
startx  = window.innerWidth
starty  = window.innerHeight
# The frames per second of the simulation. We also keep track of the time the previous frame occurred so that we know the duration between each frame.
fps       = 30.0
lastFrame = (new Date).getTime()

# The screen will flash briefly when the flash opacity is set. The opacity will dissipate quickly over time.
flashOpacity = 0.0
## Disabled for our use case

# When a bolt appears, it will be drawn at full opacity for the flash duration, and then will fade out gradually over the fade duration.
boltFlashDuration = 2## was 0.5
boltFadeDuration  = 60 ## extend the duration a bit
totalBoltDuration = boltFlashDuration + boltFadeDuration

# The list of bolts. A bolt will get added to this list on creation, and then will be automatically removed after it's done fading out.
bolts = []

# Sets the size of the canvas and each bolt canvas.
setCanvasSize = ->
  canvas.setAttribute "width",  window.innerWidth
  canvas.setAttribute "height", window.innerHeight
  for bolt in bolts
    bolt.canvas.width  = window.innerWidth
    bolt.canvas.height = window.innerHeight
  
  width   = Math.ceil window.innerWidth  / scale
  height  = Math.ceil window.innerHeight / scale
    
# Launch a bolt!!!
launchBolt = (x, y, length, direction) ->
   #flashOpacity = 0.15 + Math.random() * 0.2  # Set the flash opacity. 
  flashOpacity = 0
  # Create the bolt canvas.
  boltCanvas        = document.createElement "canvas"
  boltCanvas.width  = window.innerWidth
  boltCanvas.height = window.innerHeight
  boltContext       = boltCanvas.getContext "2d"
  boltContext.scale scale, scale
  boltDurationOffset = Math.floor(Math.random() * totalBoltDuration)
#  console.log("launchBolt[" + boltCount + "]: Direction: " + direction + " Length: " + length + " BoltDurationOffset: "+ boltDurationOffset + "/"+ totalBoltDuration)

  # Add the bolt to the list.
  ## 
  bolts.push { canvas: boltCanvas, duration: boltDurationOffset }
  # Launch it!!
  recursiveLaunchBolt x, y, length, direction, boltContext

# Recursive bolt action.
recursiveLaunchBolt = (x, y, length, direction, boltContext) ->
  originalDirection = direction
  
  # We draw the bolt incrementally to get a nice animated effect.
  boltInterval = setInterval (->
    if length <= 0
      clearInterval boltInterval
      return
    
    i = 0
    while i++ < Math.floor(1) and length > 0
      x1 = Math.floor x
      y1 = Math.floor y
      x += Math.cos direction
      y -= Math.sin direction
      length--
      
      if x1 != Math.floor(x) or y1 != Math.floor(y)
        alpha                 = Math.min boltAlphaMin, length / boltAlphaDivisor
        boltContext.fillStyle = "rgba(255, 175, 225, #{alpha})"
        boltContext.fillRect x1, y1, 2.5, 2.5
        
        direction = originalDirection + (-Math.PI / 8.0 + Math.random() * (Math.PI / 4.0))
        
        if Math.random() > 0.991
          recursiveLaunchBolt x1, y1, length * (0.3 + Math.random() * 0.4), originalDirection + (-Math.PI / 6.0 + Math.random() * (Math.PI / 3.0)), boltContext
        else if Math.random() > 0.95
          recursiveLaunchBolt x1, y1, length, originalDirection + (-Math.PI / 6.0 + Math.random() * (Math.PI / 3.0)), boltContext
          length = 0
    
    undefined
  ), 10

# This will get fired at a constant framerate.
tick = ->
  # Keep track of the frame time.
  frame     = (new Date).getTime()
  elapsed   = (frame - lastFrame) / perSec
  lastFrame = frame
  
  # Clear the canvas.
  context.clearRect 0.0, 0.0, window.innerWidth, window.innerHeight
  
  # Fire a bolt every once in a while.
  if Math.random() > 0.99
    x      = startx #Math.floor -10.0 + Math.random() * (width + 20.0)
    y      = starty #Math.floor 5.0 + Math.random() * (height / 3.0)
    length = Math.floor height / 10.0 + Math.random() * (height / 2.0)
    _d     = Math.random() * 361
    _delta      = ( frame - lastLaunch )/perSec
    _lastLaunch = lastLaunch
    lastLaunch = frame
#    console.log("["+_delta+"]Im gunna launch a bolt X: " + x + " Y: " + y + " Direction: " + _d + " Length: " + length )
    if boltCount < maxBolts
      launchBolt x, y, length, _d
    else
#      console.log("Bolt Count ("+boltCount+") Exceeds maxBolts: "+maxBolts+".")
      if _delta > maxBoltInterval
        #too much time has elapsed between bolts. We should increment the maxBolt
#        console.log("HOWEVER it's been too long since we last launched a bolt. and maxBoltInterval is "+ maxBoltInterval )
        maxBolts = maxBolts+1
#        console.log("maxBolts now "+ maxBolts )
        launchBolt x, y, length, _d

        
      #launchBolt x, y, length, Math.PI * 3.0 / 2.0
      
  # Draw the flash.
  #if flashOpacity > 0.0
  ##  context.fillStyle = "rgba(255, 255, 255, #{flashOpacity})"
  #  context.fillRect 0.0, 0.0, window.innerWidth, window.innerHeight
  #  flashOpacity = Math.max 0.0, flashOpacity - 2.0 * elapsed
  
  # Draw each bolt.
  for bolt, boltCount in bolts
    bolt.duration += elapsed
    #console.log("Bolt[" + i + "] Duration: "+ bolt.duration)
    if bolt.duration >= totalBoltDuration
#      console.log("Bolt[" + boltCount + "] SPLICE "+ bolt.duration + " " + totalBoltDuration)
      # Bolt culling.
      bolts.splice boltCount, 1
      boltCount--
      return
    
    context.globalAlpha = Math.max 0.0, Math.min(6.0, (totalBoltDuration - bolt.duration) / boltFadeDuration)
    context.drawImage bolt.canvas, 0.0, 0.0
  
  undefined

# Start it up!!!
window.addEventListener "resize", setCanvasSize
setCanvasSize()
console.log( "width " + width)
console.log("height " + height)
console.log("startx " + startx )
console.log("starty " + starty )
setInterval tick, (perSec / 2 ) / fps

Lichtenberg javascript:

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(function() {
  // https://codepen.io/jlong64/pen/kXRxpA
  // This expects to exist in an environment which has a background that's black. and has a canvas element named 'canvas'
  // https://coffeescript-cookbook.github.io/chapters/math/generating-random-numbers
  // The main canvas and context.
  var boltAlphaDivisor, boltAlphaMin, boltCount, boltFadeDuration, boltFlashDuration, bolts, canvas, context, direction, flashOpacity, fps, height, lastFrame, lastLaunch, launchBolt, maxBoltInterval, maxBolts, perSec, recursiveLaunchBolt, scale, setCanvasSize, startx, starty, tick, totalBoltDuration, width;
  canvas = document.getElementById("canvas");
  context = canvas.getContext("2d");
  boltCount = 1;
  direction = 0.00;
  lastLaunch = 0;
  perSec = 1000.0;
  maxBolts = 15;
  boltAlphaMin = 0.75;
  boltAlphaDivisor = 50;
  maxBoltInterval = 1;

  // The size and scale of the canvas. The size will get set via setCanvasSize to match the size of the window. Change the scale to get a more or less pixel-y effect.
  width = 0.0;
  height = 0.0;
  scale = .50;

  //Set the starting point of bolts to the center of the frame
  startx = window.innerWidth;
  starty = window.innerHeight;

  // The frames per second of the simulation. We also keep track of the time the previous frame occurred so that we know the duration between each frame.
  fps = 30.0;
  lastFrame = (new Date()).getTime();

  // The screen will flash briefly when the flash opacity is set. The opacity will dissipate quickly over time.
  flashOpacity = 0.0;

  //# Disabled for our use case

  // When a bolt appears, it will be drawn at full opacity for the flash duration, and then will fade out gradually over the fade duration.
  boltFlashDuration = 0; //# was 0.5
  boltFadeDuration = 60; //# extend the duration a bit
  totalBoltDuration = boltFlashDuration + boltFadeDuration;

  // The list of bolts. A bolt will get added to this list on creation, and then will be automatically removed after it's done fading out.
  bolts = [];

  // Sets the size of the canvas and each bolt canvas.
  setCanvasSize = function() {
    var bolt, j, len;
    canvas.setAttribute("width", window.innerWidth);
    canvas.setAttribute("height", window.innerHeight);
    for (j = 0, len = bolts.length; j < len; j++) {
      bolt = bolts[j];
      bolt.canvas.width = window.innerWidth;
      bolt.canvas.height = window.innerHeight;
    }
    width = Math.ceil(window.innerWidth / scale);
    return height = Math.ceil(window.innerHeight / scale);
  };

  
  // Launch a bolt!!!
  launchBolt = function(x, y, length, direction) {
    var boltCanvas, boltContext, boltDurationOffset;
    //flashOpacity = 0.15 + Math.random() * 0.2  # Set the flash opacity. 
    flashOpacity = 0;
    //Create the bolt canvas.
    boltCanvas = document.createElement("canvas");
    boltCanvas.width = window.innerWidth;
    boltCanvas.height = window.innerHeight;
    boltContext = boltCanvas.getContext("2d");
    boltContext.scale(scale, scale);
    boltDurationOffset = Math.floor(Math.random() * totalBoltDuration);
    //console.log("launchBolt[" + boltCount + "]: Direction: " + direction + " Length: " + length + " BoltDurationOffset: "+ boltDurationOffset + "/"+ totalBoltDuration)
    // Add the bolt to the list.
    //# 
    bolts.push({
      canvas: boltCanvas,
      duration: boltDurationOffset
    });
    // Launch it!!
    return recursiveLaunchBolt(x, y, length, direction, boltContext);
  };

  // Recursive bolt action.
  recursiveLaunchBolt = function(x, y, length, direction, boltContext) {
    var boltInterval, originalDirection;
    originalDirection = direction;
    
    // We draw the bolt incrementally to get a nice animated effect.
    return boltInterval = setInterval((function() {
      var alpha, i, x1, y1;
      if (length <= 0) {
        clearInterval(boltInterval);
        return;
      }
      i = 0;
      while (i++ < Math.floor(1) && length > 0) {
        x1 = Math.floor(x);
        y1 = Math.floor(y);
        x += Math.cos(direction);
        y -= Math.sin(direction);
        length--;
        if (x1 !== Math.floor(x) || y1 !== Math.floor(y)) {
          alpha = Math.min(boltAlphaMin, length / boltAlphaDivisor);
          boltContext.fillStyle = `rgba(255, 195, 235, ${alpha})`;
          boltContext.fillRect(x1, y1, 2.5, 2.5);
          direction = originalDirection + (-Math.PI / 8.0 + Math.random() * (Math.PI / 4.0));
          if (Math.random() > 0.991) {
            recursiveLaunchBolt(x1, y1, length * (0.3 + Math.random() * 0.4), originalDirection + (-Math.PI / 6.0 + Math.random() * (Math.PI / 3.0)), boltContext);
          } else if (Math.random() > 0.95) {
            recursiveLaunchBolt(x1, y1, length, originalDirection + (-Math.PI / 6.0 + Math.random() * (Math.PI / 3.0)), boltContext);
            length = 0;
          }
        }
      }
      return void 0;
    }), 10);
  };

  // This will get fired at a constant framerate.
  tick = function() {
    var _d, _delta, _lastLaunch, bolt, elapsed, frame, j, len, length, x, y;
    // Keep track of the frame time.
    frame = (new Date()).getTime();
    elapsed = (frame - lastFrame) / perSec;
    lastFrame = frame;
    
    // Clear the canvas.
    context.clearRect(0.0, 0.0, window.innerWidth, window.innerHeight);
    
    // Fire a bolt every once in a while.
    if (Math.random() > 0.99) {
      x = startx; //Math.floor -10.0 + Math.random() * (width + 20.0)
      y = starty; //Math.floor 5.0 + Math.random() * (height / 3.0)
      length = Math.floor(height / 10.0 + Math.random() * (height / 2.0));
      _d = Math.random() * 361;
      _delta = (frame - lastLaunch) / perSec;
      _lastLaunch = lastLaunch;
      lastLaunch = frame;
      //    console.log("["+_delta+"]Im gunna launch a bolt X: " + x + " Y: " + y + " Direction: " + _d + " Length: " + length )
      if (boltCount < maxBolts) {
        launchBolt(x, y, length, _d);
      } else {
        //      console.log("Bolt Count ("+boltCount+") Exceeds maxBolts: "+maxBolts+".")
        if (_delta > maxBoltInterval) {
          //too much time has elapsed between bolts. We should increment the maxBolt
          //console.log("HOWEVER it's been too long since we last launched a bolt. and maxBoltInterval is "+ maxBoltInterval )
          maxBolts = maxBolts + 1;
          //console.log("maxBolts now "+ maxBolts )
          launchBolt(x, y, length, _d);
        }
      }
    }

    // Draw each bolt.
    for (boltCount = j = 0, len = bolts.length; j < len; boltCount = ++j) {
      bolt = bolts[boltCount];
      bolt.duration += elapsed;
      //console.log("Bolt[" + i + "] Duration: "+ bolt.duration)
      if (bolt.duration >= totalBoltDuration) {
        //console.log("Bolt[" + boltCount + "] SPLICE "+ bolt.duration + " " + totalBoltDuration)
        // Bolt culling.
        bolts.splice(boltCount, 1);
        boltCount--;
        return;
      }
      context.globalAlpha = Math.max(0.0, Math.min(1.0, (totalBoltDuration - bolt.duration) / boltFadeDuration));
      context.drawImage(bolt.canvas, 0.0, 0.0);
    }
    return void 0;
  };

  // Start it up!!!
  window.addEventListener("resize", setCanvasSize);
  setCanvasSize();
  //console.log("width " + width);
  //console.log("height " + height);
  //console.log("startx " + startx);
  //console.log("starty " + starty);
  setInterval(tick, (perSec / 2) / fps);
}).call(this);