High-Performance JavaScript - HTML5 Game Development Insights - page 45

// in this step we create new particles instead of recycling them
demo.notRecyclingStep = function( particles ) {
var i;
for (i = 0; i < demo.settings.rate; i++) {
var min = -10,
max = 10,
velx = min + Math.random() * (max - min),
vely = min + Math.random() * (max - min),
x = demo.settings.width * 0.5,
y = demo.settings.height * 0.5,
w = demo.settings.size,
h = demo.settings.size,
life = demo.settings.life;
// continuously pushing new objects in an array cause high memory churn and should be
avoided
particles.push( new demo.Particle( x, y, w, h, life ).setVel( velx, vely ) );
}
for (i = 0; i < particles.length; i++) {
var particle = particles[i];
if( particle.life === 0 ){
// splicing like pushing should be avoided
particles.splice(i, 1);
i--;
}
else if(demo.settings.cull === true && demo.isInBounds(particle) === false){
// splicing like pushing should be avoided
particles.splice(i, 1);
i--;
}
else
demo.integrate( particle );
particle.life--;
}
if( demo.settings.render === true )
demo.draw( demo.particles );
};