JS1k 2010 - 47 - Details - A ground breaking JavaScript golfing competition

Author:

antimatter15

Twitter:

GitHub:

Facebook:

Google+:

Reddit:

/r/

Pouet:

Website:

antimatter15.com

Compo:

classic

Demo link:

https://js1k.com/2010-first/demo/47

Shortlink:

https://js1k.com/47

Blog post:

please update here!

Bytes:

906

Chars:

906

Submission

var a=document.getElementById("c");document.body.setAttribute("style","margin:0;left:0;top:0;padding:0");a.width=innerWidth;a.height=innerHeight;var c=a.getContext("2d"),f=[[300,100,10,-0.2,0],[300,300,10,0.2,0]],h=-1; setInterval(function(){if(h>0)f[h][2]+=0.1;c.clearRect(0,0,innerWidth,innerHeight);for(var d=f.length,b=d,e;b--;){for(e=d;e--;)if(e!=b&&b!=h&&e!=h){var i=f[e][0]-f[b][0],j=f[e][1]-f[b][1],g=i*i+j*j,k=Math.sqrt(g);g=f[e][2]/g;f[b][3]+=i/k*g;f[b][4]+=j/k*g}f[b][0]+=f[b][3];f[b][1]+=f[b][4];c.fillStyle="hsl("+Math.min(300,Math.floor(50*Math.sqrt(f[b][3]*f[b][3]+f[b][4]*f[b][4])))+",100%,40%)";c.beginPath();c.arc(f[b][0],f[b][1],f[b][2],0,Math.PI*2,true);c.fill()}},0); document.body.onmousedown=function(d){h=f.length;f.push([d.clientX,d.clientY,2,0,0]);return false};document.body.onmouseup=function(d){f[h][3]=(d.clientX-f[h][0])/100;f[h][4]=(d.clientY-f[h][1])/100;h=-1;return false}

Description

Updated version of gravity submission. Click to add a dot, the size is determined by amount of time the mouse was down, position is determined by where you click and initial velocity is the distance from where you first moused down and where you mouse upped.

Base64 encoded

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Original source

<body>
<canvas id="c"></canvas>
<script>
var canvas = document.getElementById('c');
document.body.setAttribute('style','margin:0;left:0;top:0;padding:0')
canvas.width = innerWidth;
canvas.height = innerHeight;
var context = canvas.getContext('2d')
var planets = [
[300,100,10,-0.2,0],
[300,300,10,0.2,0], //x,y,r,xv,yv
];
var selected = -1;

setInterval(function(){
	if(selected > 0) planets[selected][2]+=0.1;
	context.clearRect(0,0,innerWidth,innerHeight)
	for(var plen = planets.length, a = plen, b; a--;){
		for(b = plen; b--;){
			if(b!=a && a != selected && b != selected){ //there is no friction in space. Plus it'll yield a divide by zero error
				//inverse square law: force = mass/distance-squared;
				var dx = planets[b][0] - planets[a][0];
				var dy = planets[b][1] - planets[a][1];
				var d2 = dx*dx + dy*dy;
				var d = Math.sqrt(d2);
				var force = planets[b][2]/d2;
				planets[a][3] += dx / d * force; //possible optimization: force = force/d 
				planets[a][4] += dy / d * force; //and sumY += dy / force
			}
		}		
		planets[a][0] += planets[a][3];
		planets[a][1] += planets[a][4];
		context.fillStyle = "hsl(" + Math.min(300, Math.floor(50 * Math.sqrt(planets[a][3] * planets[a][3] + planets[a][4] * planets[a][4]))) + ",100%,40%)"; 
		context.beginPath();
		context.arc(planets[a][0], planets[a][1], planets[a][2], 0, Math.PI * 2, true);
		context.fill() 
	}
},0)
document.body.onmousedown = function(e){
	selected = planets.length;
	planets.push([e.clientX,e.clientY,2,0,0])
	return false
}
document.body.onmouseup = function(e){
	planets[selected][3] = (e.clientX - planets[selected][0])/100;
	planets[selected][4] = (e.clientY - planets[selected][1])/100;
	selected = -1;
	return false
}
</script>
</body>

JS1k: The JavaScript code golfing competition

2010 - The Original