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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);
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