prosperon/scripts/particle.js

115 lines
2.6 KiB
JavaScript

var emitter = {};
emitter.particles = {};
emitter.life = 10;
emitter.scale = 1;
emitter.grow_for = 0;
emitter.spawn_timer = 0;
emitter.pps = 0;
emitter.color = Color.white;
emitter.draw = function () {
var pars = Object.values(this.particles);
if (pars.length === 0) return;
render.use_shader(this.shader);
render.use_mat(this);
render.make_particle_ssbo(pars, this.ssbo);
render.draw(this.shape, this.ssbo, pars.length);
};
emitter.kill = function () {
emitters.remove(this);
};
var std_step = function (p) {
if (p.time < this.grow_for) {
var s = Math.lerp(0, this.scale, p.time / this.grow_for);
p.transform.scale = [s, s, s];
} else if (p.time > p.life - this.shrink_for) {
var s = Math.lerp(0, this.scale, (p.life - p.time) / this.shrink_for);
p.transform.scale = [s, s, s];
} else p.transform.scale = [this.scale, this.scale, this.scale];
};
emitter.step_hook = std_step;
emitter.spawn = function (t) {
t ??= this.transform;
var par = this.dead.shift();
if (par) {
par.body.pos = t.pos;
par.transform.scale = [this.scale, this.scale, this.scale];
this.particles[par.id] = par;
par.time = 0;
this.spawn_hook?.(par);
par.life = this.life;
return;
}
par = {
transform: os.make_transform(),
life: this.life,
time: 0,
color: this.color,
};
par.body = os.make_body(par.transform);
par.body.pos = t.pos;
par.transform.scale = [this.scale, this.scale, this.scale];
par.id = prosperon.guid();
this.particles[par.id] = par;
this.spawn_hook(par);
};
emitter.step = function (dt) {
// update spawning particles
if (this.on && this.pps > 0) {
this.spawn_timer += dt;
var pp = 1 / this.pps;
while (this.spawn_timer > pp) {
this.spawn_timer -= pp;
this.spawn();
}
}
// update all particles
for (var p of Object.values(this.particles)) {
p.time += dt;
this.step_hook?.(p);
if (this.kill_hook?.(p) || p.time >= p.life) {
this.die_hook?.(p);
this.dead.push(this.particles[p.id]);
delete this.particles[p.id];
}
}
};
emitter.burst = function (count, t) {
for (var i = 0; i < count; i++) this.spawn(t);
};
var emitters = [];
var make_emitter = function () {
var e = Object.create(emitter);
e.ssbo = render.make_textssbo();
e.shape = shape.centered_quad;
e.shader = "shaders/baseparticle.cg";
e.dead = [];
emitters.push(e);
return e;
};
function update_emitters(dt) {
for (var e of emitters) e.step(dt);
}
function draw_emitters() {
for (var e of emitters) e.draw();
}
return { make_emitter, update_emitters, draw_emitters };