#include "fountain.h"
#include <cstdlib>
#include <ctime>
#include <cmath>
using namespace std;

#define SPAWN_RATE .05
#define MAX_AGE 10

Fountain::Fountain() {
    _time_accum = 5*(double(rand())/RAND_MAX);
}

void Fountain::update(double time_elapsed, int spectrum_size, double* spectrum, double* spectrum2) {

    
    _time_accum += time_elapsed;

    for (int i = 0; i < _particles.size(); i++) {
        _particles[i].age += time_elapsed;
        _particles[i].x += _particles[i].vx * time_elapsed;
        _particles[i].y += _particles[i].vy * time_elapsed;
        _particles[i].vx += -.03 * abs(_particles[i].vy) * _particles[i].x;
        _particles[i].vx *= .999;
        //_particles[i].vy *= .9999;
        _particles[i].vy += .2 * time_elapsed;
    }

    double sum = 0;
    for (int i = 0; i < spectrum_size; i++) {
        sum += spectrum[i];// - spectrum2[i];
    }
    if (sum < 0) sum = 0;
    _spawn_rate = SPAWN_RATE / (sum*sum);

    

    if (_time_accum > _spawn_rate) {
        _time_accum -= _spawn_rate;
        Particle p;
        p.x = (double(rand())/RAND_MAX - .5) * .01;
        p.y = (double(rand())/RAND_MAX - .5) * .1 - .8;
        p.vy = -.4 + sum * (double(rand())/RAND_MAX + .5);
        p.vx = .3 * sum * (double(rand())/RAND_MAX + .5);
        if (rand()%2) p.vx *= -1;
        p.age = 0;
        _particles.push_back(p);
    }

    if (_particles.size() > 0 && _particles[0].y > 1.3) _particles.pop_front();

    int i = 0;
//  while (i < _particles.size()) {
//      if (_particles[i].y > 1.3) _particles.erase(_particles.begin() + i);
//      else i++;
//  }

}

void Fountain::draw() {
    glBegin(GL_POINTS);
    for (int i = 0; i < _particles.size(); i++) {
        glColor4f(1 - abs(_particles[i].vx), 1 - _particles[i].age ,1,1 - _particles[i].age);
        glVertex2f(_particles[i].x, _particles[i].y);
    }
    glEnd();
}