var demo = function(){
var data = {
x:0,
y:0,
x1:0,
y1:0,
u:0,
i:0,
d:0,
d2:0,
l:0,
nx:0,
ny:0,
result:false,
}
if(typeof Math.hypot !== "function"){
Math.hypot = function(x, y){ return Math.sqrt(x * x + y * y);};
}
var lineSegCircleIntercept = function(ret, x1, y1, x2, y2, cx, cy, r){
var vx, vy, u, u1, u2, d, ld, len, xx, yy;
vx = x2 - x1;
vy = y2 - y1;
ret.d2 = (vx * vx + vy * vy);
ret.u = u = ((cx - x1) * vx + (cy - y1) * vy) / ret.d2;
xx = x1 + vx * u;
yy = y1 + vy * u;
ret.d = d = Math.hypot(xx - cx, yy - cy);
if(d <= r){
ld = Math.sqrt(r * r - d * d) / Math.sqrt(ret.d2);
u1 = u + ld;
if(u1 < 0){
ret.result = false;
return ret;
}
u2 = u - ld;
if(u2 > 1){
ret.result = false;
return ret;
}
ret.i = 0;
if(u1 <= 1){
ret.i += 1;
ret.x = x1 + vx * u1;
ret.y = y1 + vy * u1;
}else{
ret.x = x2;
ret.y = y2;
}
if(u2 >= 0){
ret.x1 = x1 + vx * u2;
ret.y1 = y1 + vy * u2;
ret.i += 2;
}else{
ret.x1 = x1;
ret.y1 = y1;
}
ret.result = true;
return ret;
}
ret.x = null;
ret.result = false;
return ret;
}
var canvas = (function(){
var canvas = document.getElementById("canv");
if(canvas !== null){
document.body.removeChild(canvas);
}
canvas = document.createElement("canvas");
canvas.id = "canv";
canvas.width = window.innerWidth;
canvas.height = window.innerHeight;
canvas.style.position = "absolute";
canvas.style.top = "0px";
canvas.style.left = "0px";
canvas.style.zIndex = 1000;
canvas.ctx = canvas.getContext("2d");
document.body.appendChild(canvas);
return canvas;
})();
var ctx = canvas.ctx;
var canvasMouseCallBack = undefined;
var mouse = (function(){
var mouse = {
x : 0, y : 0, w : 0, alt : false, shift : false, ctrl : false,
interfaceId : 0, buttonLastRaw : 0, buttonRaw : 0,
over : false,
bm : [1, 2, 4, 6, 5, 3],
getInterfaceId : function () { return this.interfaceId++; },
startMouse:undefined,
};
function mouseMove(e) {
var t = e.type, m = mouse;
m.x = e.offsetX; m.y = e.offsetY;
if (m.x === undefined) { m.x = e.clientX; m.y = e.clientY; }
m.alt = e.altKey;m.shift = e.shiftKey;m.ctrl = e.ctrlKey;
if (t === "mousedown") { m.buttonRaw |= m.bm[e.which-1];
} else if (t === "mouseup") { m.buttonRaw &= m.bm[e.which + 2];
} else if (t === "mouseout") { m.buttonRaw = 0; m.over = false;
} else if (t === "mouseover") { m.over = true;
} else if (t === "mousewheel") { m.w = e.wheelDelta;
} else if (t === "DOMMouseScroll") { m.w = -e.detail;}
if (canvasMouseCallBack) { canvasMouseCallBack(m.x, m.y); }
e.preventDefault();
}
function startMouse(element){
if(element === undefined){
element = document;
}
"mousemove,mousedown,mouseup,mouseout,mouseover,mousewheel,DOMMouseScroll".split(",").forEach(
function(n){element.addEventListener(n, mouseMove);});
element.addEventListener("contextmenu", function (e) {e.preventDefault();}, false);
}
mouse.mouseStart = startMouse;
return mouse;
})();
if(typeof canvas === "undefined"){
mouse.mouseStart(canvas);
}else{
mouse.mouseStart();
}
function drawCircle(ctx,x,y,r,col,col1,lWidth){
if(col1){
ctx.lineWidth = lWidth;
ctx.strokeStyle = col1;
}
if(col){
ctx.fillStyle = col;
}
ctx.beginPath();
ctx.arc( x, y, r, 0, Math.PI*2);
if(col){
ctx.fill();
}
if(col1){
ctx.stroke();
}
}
function drawLine(ctx,x1,y1,x2,y2,col,lWidth){
ctx.lineWidth = lWidth;
ctx.strokeStyle = col;
ctx.beginPath();
ctx.moveTo(x1,y1);
ctx.lineTo(x2,y2);
ctx.stroke();
}
var h = canvas.height;
var w = canvas.width;
var unit = Math.ceil(Math.sqrt(Math.hypot(w, h)) / 32);
const U80 = unit * 80;
const U60 = unit * 60;
const U40 = unit * 40;
const U10 = unit * 10;
var lines = [
{x1 : U80, y1 : U80, x2 : w /2, y2 : h - U80},
{x1 : w - U80, y1 : U80, x2 : w /2, y2 : h - U80},
{x1 : w / 2 - U10, y1 : h / 2 - U40, x2 : w /2, y2 : h/2 + U10 * 2},
{x1 : w / 2 + U10, y1 : h / 2 - U40, x2 : w /2, y2 : h/2 + U10 * 2},
];
function update(){
var i, l;
ctx.clearRect(0, 0, w, h);
drawCircle(ctx, mouse.x, mouse.y, U60, undefined, "black", unit * 3);
drawCircle(ctx, mouse.x, mouse.y, U60, undefined, "yellow", unit * 2);
for(i = 0; i < lines.length; i ++){
l = lines[i]
drawLine(ctx, l.x1, l.y1, l.x2, l.y2, "black" , unit * 3)
drawLine(ctx, l.x1, l.y1, l.x2, l.y2, "yellow" , unit * 2)
data = lineSegCircleIntercept(data, l.x1, l.y1, l.x2, l.y2, mouse.x, mouse.y, U60);
if(data.result){
drawLine(ctx, l.x1, l.y1, l.x2, l.y2, "red" , unit * 2)
if((data.i & 1) === 1){
drawCircle(ctx, data.x, data.y, unit * 4, "white", "red", unit );
}else{
drawCircle(ctx, data.x, data.y, unit * 2, "white", "green", unit );
}
if((data.i & 2) === 2){
drawCircle(ctx, data.x1, data.y1, unit * 4, "white", "red", unit );
}else{
drawCircle(ctx, data.x1, data.y1, unit * 2, "white", "green", unit );
}
}
}
requestAnimationFrame(update);
}
update();
}
window.addEventListener("resize",demo);
demo();