triangles/Particle.cpp

/**
 *  Triangles
 *  Copyright (C) 2016 POSITIVE MENTAL ATTITUDE
 *
 *  This program is free software: you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation, version 3 of the License.
 *
 *  This program is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */
 
 /**
  * This is based on a wiki entry
  * https://github.com/SFML/SFML/wiki/Source:-Particle-System
  */

#include <sstream>
#include "Particle.hpp"

ParticleSystem::ParticleSystem( int width, int height )
{
	_transparent = sf::Color( 0, 0, 0, 0 );
	_image.create( width, height, _transparent );
	_texture.loadFromImage(_image);
	_sprite = sf::Sprite(_texture);
	_position.x	= 0.5f * width;
	_position.y	= 0.5f * height;
	_particleSpeed = 20.0f;
	_dissolutionRate = 60.f;
}

ParticleSystem::~ParticleSystem()
{
	for(auto it = _particles.begin(); it != _particles.end(); it++)
	{
		delete *it;
	}
}

void ParticleSystem::fuel(int particles, float angle)
{
	Particle* particle;
	const double degree = 3.14159265358 / 180.;
	for(int i = 0; i < particles; i++)
	{
		particle = new Particle();
		particle->pos.x = _position.x;
		particle->pos.y = _position.y;
	
		do
		{
			particle->vel.x = _randomizer.rnd(0.0f, 15.0f) * -std::sin(angle * degree);
			particle->vel.y = _randomizer.rnd(0.0f, 15.0f) * std::cos(angle * degree);
		} while(particle->vel.x == 0.0f && particle->vel.y == 0.0f);

		particle->color.r = std::rand() % 100 + 150;
		particle->color.g = std::rand() % 50 + 150;
        particle->color.b = std::rand() % 50;
		particle->transparency = 255.f;
		particle->color.a = sf::Uint8(particle->transparency);
		_particles.push_back(particle);
	}
}
#include "iostream"
void ParticleSystem::update(sf::Time delta)
{
	float time = delta.asSeconds();

	for(auto it = _particles.begin(); it != _particles.end(); it++ )
	{
        (*it)->pos.x += (*it)->vel.x * time * _particleSpeed;
	    (*it)->pos.y += (*it)->vel.y * time * _particleSpeed;

		(*it)->transparency -= (_dissolutionRate * time);
		(*it)->color.a = sf::Uint8((*it)->transparency);

		if((*it)->pos.x > _image.getSize().x || (*it)->pos.x < 0 || (*it)->pos.y > _image.getSize().y || (*it)->pos.y < 0 || (*it)->color.a < 10)
		{
            delete (*it);
		    it = _particles.erase(it);
		    if(it == _particles.end()) 
				return;
        }
	}
}

void ParticleSystem::render()
{
	for(auto it = _particles.begin(); it != _particles.end(); it++ )
	{
  	  _image.setPixel( (int)(*it)->pos.x, (int)(*it)->pos.y, (*it)->color );
	}
    _texture.update(_image);
}

void ParticleSystem::clear()
{
	for(auto it = _particles.begin(); it != _particles.end(); it++ )
	{
	    _image.setPixel( (int)(*it)->pos.x, (int)(*it)->pos.y, _transparent );
	}
}