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ball.js
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ball.js
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/* Copyright (c) 2017 Nicholas Maltbie
* MIT License
*
* Ball.js - graphcial and physics ball file
*/
var left = 0
var right = 480
//function to make a ball
function ball(x_start, y_start, color, speedx, speedy, radius)
{
//Save values for ball
this.x = x_start
this.y = y_start
this.speedx = speedx
this.speedy = speedy
this.color = color
this.radius = radius
this.dying = false;
this.time = 0;
this.death_timer = 0;
this.full = this.radius;
this.arc = Math.PI * 2;
//Check if two circles intersect
this.intersect = function (circle)
{
dx = this.x - circle.x
dy = this.y - circle.y
rsum = this.radius + circle.radius
return dx * dx + dy * dy <= rsum * rsum
}
this.die = function(time, fall_speed = 0)
{
this.dying = true;
this.death_timer = time;
this.time = time;
this.speedy = fall_speed;
}
this.is_dead = function ()
{
return this.dying && this.time <= 0
}
this.draw = function (elapsed)
{
if (this.dying) {
this.time -= elapsed;
this.radius = Math.max(0, this.full * this.time / this.death_timer);
if(this.time <= 0) {
remove_object(this.id)
return
}
}
//Calculate movement across the x and y axis
var dx = this.speedx * elapsed
var dy = this.speedy * elapsed
//If ball goes off the screen switch direction.
if (dx + this.x + this.radius / 2 > right - this.radius ||
dx + this.x - this.radius / 2 < this.radius + left) {
this.speedx = -this.speedx
dx = -dx
}
//Move object based on dx and dy
this.x += dx
this.y += dy
//Draw ball at its current location
ctx.beginPath()
ctx.arc(this.x, this.y, this.radius, 0, this.arc)
ctx.fillStyle = this.color
ctx.fill()
ctx.closePath()
}
}