module objects

import gg

pub struct Particle {
pub mut:
    color    gg.Color
    pos      Vector
    vel      Vector
    accel    Vector
    lifespan f32 = 255
}

pub fn (particle Particle) draw(mut ctx gg.Context) {
    ctx.draw_circle_filled(particle.pos.x, get_params().height - particle.pos.y,
        get_params().particle_radius, particle.color)
}

pub fn (mut particle Particle) tick(mut rocket Rocket, mut ctx gg.Context) {
    particle.lifespan -= get_params().age_rate
    particle.color.a = u8(particle.lifespan)

    if particle.lifespan <= 0 {
        rocket.dead = true
        return
    }

    particle.accel += get_params().gravity
    particle.vel += particle.accel
    particle.vel = particle.vel.mult(get_params().drag)
    particle.pos += particle.vel
    particle.draw(mut ctx)

    particle.accel = Vector{}
}