snipplets.dev/projects/JavaScript/Circle_Collision/app.js

81 lines
2.3 KiB
JavaScript

var circle = {x: 50, y: 50, radius: 50, contour: []};
var box = {x: 20, y: 20, width: 300, height: 300};
for(var a = 0; a < Math.PI * 2; a += Math.PI / circle.radius){
circle.contour.push({
_x: Math.sin(a) * circle.radius, _y: Math.cos(a) * circle.radius
});
}
var canvas = document.body.appendChild(document.createElement("canvas")).getContext("2d");
canvas.canvas.width = 400;
canvas.canvas.height = 400;
var loop = function(){
canvas.canvas.width = canvas.canvas.width;
canvas.save();
canvas.fillRect(box.x, box.y, box.width, box.height);
canvas.globalCompositeOperation = "destination-out";
canvas.fillRect(box.x + 20, box.y + 20, box.width - 40, box.height - 40);
canvas.restore();
var circleCanvas = document.createElement("canvas").getContext("2d");
circleCanvas.canvas.width = canvas.canvas.width;
circleCanvas.canvas.height = canvas.canvas.height;
circleCanvas.save();
circleCanvas.arc(circle.x, circle.y, circle.radius, 0, Math.PI * 2);
circleCanvas.fillStyle = "#aaa";
circleCanvas.fill();
circleCanvas.globalCompositeOperation = "destination-in";
circleCanvas.fillRect(box.x + 20, box.y + 20, box.width - 40, box.height - 40);
circleCanvas.restore();
canvas.drawImage(circleCanvas.canvas, 0, 0);
if(circle._x < box.x + 20){
circle._x = box.x + 20;
}
if(circle._y < box.y + 20){
circle._y = box.y + 20;
}
if(circle._x > box.x + box.width - 20){
circle._x = box.x + box.width - 20;
}
if(circle._y > box.y + box.height - 20){
circle._y = box.y + box.height - 20;
}
circle.contour.forEach(function(p){
p.x = p._x;
p.y = p._y;
if(circle.x + p.x < box.x + 20){
p.x = box.x + 20 - circle.x;
}
if(circle.y + p.y < box.y + 20){
p.y = box.y + 20 - circle.y;
}
if(circle.x + p.x > box.x + box.width - 20){
p.x = box.x + box.width - 20 - circle.x;
}
if(circle.y + p.y > box.y + box.height - 20){
p.y = box.y + box.height - 20 - circle.y;
}
canvas.strokeStyle = "green";
canvas.lineWidth = 3;
canvas.lineTo(p.x + circle.x, p.y + circle.y);
});
canvas.stroke();
circle.x = circle._x;
circle.y = circle._y;
requestAnimationFrame(loop);
};
loop();
document.onmousemove = function(event){
circle._x = event.layerX;
circle._y = event.layerY;
};