Particle System Class

[Lillebror]

Hello everyone, I've just begun learning SFML (went from Allegro).
I've made a particle system class that has been great fun to play around with. It's not particularly useful (or effective I guess) since it can only be drawn by drawing the image (sprite) the particles (pixels) are plotted on.

Enough said, try it out for yourselves!

particle.h

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#ifndef PARTICLE_H
#define PARTICLE_H

#include <SFML\System\Vector2.hpp>
#include <SFML\System\Clock.hpp>
#include <SFML\System\Randomizer.hpp>
#include <SFML\Graphics\Color.hpp>
#include <SFML\Graphics\Image.hpp>
#include <SFML\Graphics\Sprite.hpp>
#include <list>

namespace Shape { enum { CIRCLE, SQUARE }; }

struct Particle
{
sf::Vector2f pos; // Position
sf::Vector2f vel; // Velocity
sf::Color color; // RGBA
};

typedef std::list<Particle*>::iterator ParticleIterator;

class ParticleSystem
{
public:
ParticleSystem( int width, int height );
~ParticleSystem();

void fuel( int particles ); // Adds new particles to m_particles
void update(); // Updates position, velocity and opacity of all particles
void render(); // Renders all particles onto m_image
void remove(); // Removes all particles from m_image

void setPosition( float x, float y ) { m_position.x = x; m_position.y = y; }
void setGravity( float x, float y ) { m_gravity.x = x; m_gravity.y = y; }
void setParticleSpeed( float speed ) { m_particleSpeed = speed; }
void setDissolve( bool enable ) { m_dissolve = enable; }
void setDissolutionRate( unsigned char rate ) { m_dissolutionRate = rate; }
void setShape( unsigned char shape ) { m_shape = shape; }

int getNumberOfParticles() { return m_particles.size(); }
std::string getNumberOfParticlesString();
sf::Sprite& getSprite() { return m_sprite; }

private:
sf::Vector2f m_position; // Particle origin (pixel co-ordinates)
sf::Vector2f m_gravity; // Affects particle velocities
sf::Randomizer m_randomizer; // Randomizes particle velocities
sf::Clock m_clock; // Used to scale particle motion
sf::Color m_transparent; // sf::Color( 0, 0, 0, 0 )
sf::Image m_image; // See render() and remove()
sf::Sprite m_sprite; // Connected to m_image
float m_particleSpeed; // Pixels per second (at most)
bool m_dissolve; // Dissolution enabled?
unsigned char m_dissolutionRate;
unsigned char m_shape;

std::list<Particle*> m_particles;
};

#endif


particle.cpp

Code: [Select]

#include "particle.h"
#include <sstream>

ParticleSystem::ParticleSystem( int width, int height )
{
m_transparent = sf::Color( 0, 0, 0, 0 );
m_image.Create( width, height, m_transparent );
m_sprite.SetImage( m_image );

m_position.x = 0.5f * width;
m_position.y = 0.5f * height;
m_particleSpeed = 20.0f;
m_dissolve = false;
m_dissolutionRate = 4;
m_shape = Shape::CIRCLE;
}

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

void ParticleSystem::fuel( int particles )
{
float angle;
Particle* particle;
for( int i = 0; i < particles; i++ )
{
particle = new Particle();
particle->pos.x = m_position.x;
particle->pos.y = m_position.y;

switch( m_shape )
{
case Shape::CIRCLE:
angle = m_randomizer.Random( 0.0f, 6.2832f );
particle->vel.x = m_randomizer.Random( 0.0f, cos( angle ) );
particle->vel.y = m_randomizer.Random( 0.0f, sin( angle ) );
break;
case Shape::SQUARE:
particle->vel.x = m_randomizer.Random( -1.0f, 1.0f );
particle->vel.y = m_randomizer.Random( -1.0f, 1.0f );
break;
default:
particle->vel.x = 0.5f; // Easily detected
particle->vel.y = 0.5f; // Easily detected
}

if( particle->vel.x == 0.0f && particle->vel.y == 0.0f )
{
delete particle;
continue;
}

particle->color.r = m_randomizer.Random( 0, 255 );
particle->color.g = m_randomizer.Random( 0, 255 );
particle->color.b = m_randomizer.Random( 0, 255 );
particle->color.a = 255;
m_particles.push_back( particle );
}
}

void ParticleSystem::update()
{
float time = m_clock.GetElapsedTime();
m_clock.Reset();

for( ParticleIterator it = m_particles.begin(); it != m_particles.end(); it++ )
{
(*it)->vel.x += m_gravity.x * time;
(*it)->vel.y += m_gravity.y * time;

(*it)->pos.x += (*it)->vel.x * time * m_particleSpeed;
(*it)->pos.y += (*it)->vel.y * time * m_particleSpeed;

if( m_dissolve ) (*it)->color.a -= m_dissolutionRate;

if( (*it)->pos.x > m_image.GetWidth() || (*it)->pos.x < 0 || (*it)->pos.y > m_image.GetHeight() || (*it)->pos.y < 0 || (*it)->color.a < 10 )
{
delete (*it);
it = m_particles.erase( it );
if( it == m_particles.end() ) return;
}
}
}

void ParticleSystem::render()
{
for( ParticleIterator it = m_particles.begin(); it != m_particles.end(); it++ )
{
m_image.SetPixel( (int)(*it)->pos.x, (int)(*it)->pos.y, (*it)->color );
}
}

void ParticleSystem::remove()
{
for( ParticleIterator it = m_particles.begin(); it != m_particles.end(); it++ )
{
m_image.SetPixel( (int)(*it)->pos.x, (int)(*it)->pos.y, m_transparent );
}
}

std::string ParticleSystem::getNumberOfParticlesString()
{
std::ostringstream oss;
oss << m_particles.size();
return oss.str();
}


main.cpp (ugly as hell!)

Code: [Select]

#include <SFML/Window.hpp>
#include <SFML/Graphics/RenderWindow.hpp>
#include <SFML/Graphics/Text.hpp>
#include "particle.h"

int main()
{
int width = 640;
int height = 480;

sf::RenderWindow window( sf::VideoMode( width, height, 32 ), "Inside the Particle Storm" );
window.UseVerticalSync( true );
const sf::Input& input = window.GetInput();
sf::Event events;
sf::Font font;
if( !font.LoadFromFile( "arial.ttf" ) ) return 1;
sf::Text text( "", font, 10 );
text.SetPosition( 10.0f, 10.0f );

ParticleSystem particleSystem( width, height );
//particleSystem.setPosition( width/2, height/2 );
//particleSystem.setGravity( 1.0f, 1.0f );
particleSystem.setParticleSpeed( 80.0f );
//particleSystem.setDissolve( true );
//particleSystem.setDissolutionRate( 4 );
//particleSystem.setShape( Shape::SQUARE );
particleSystem.fuel( 1000 );

float xpos = 320.0f;
float ypos = 240.0f;
float xgrv = 0.0f;
float ygrv = 0.0f;
float angle = 0.0f;

while( window.IsOpened() )
{
window.GetEvent( events );
if( events.Type == sf::Event::Closed )
window.Close();
if( events.Type == sf::Event::KeyPressed && events.Key.Code == sf::Key::Escape )
window.Close();

if( input.IsKeyDown( sf::Key::Space ) )
particleSystem.fuel( 200 * window.GetFrameTime() );
if( input.IsKeyDown( sf::Key::A ) ) --xpos;
//particleSystem.setPosition( --xpos, ypos );
if( input.IsKeyDown( sf::Key::D ) ) ++xpos;
//particleSystem.setPosition( ++xpos, ypos );
if( input.IsKeyDown( sf::Key::W ) ) --ypos;
//particleSystem.setPosition( xpos, --ypos );
if( input.IsKeyDown( sf::Key::S ) ) ++ypos;
//particleSystem.setPosition( xpos, ++ypos );
if( input.IsKeyDown( sf::Key::Left ) )
particleSystem.setGravity( --xgrv * 0.1f, ygrv * 0.1f);
if( input.IsKeyDown( sf::Key::Right ) )
particleSystem.setGravity( ++xgrv * 0.1f, ygrv * 0.1f );
if( input.IsKeyDown( sf::Key::Up ) )
particleSystem.setGravity( xgrv * 0.1f, --ygrv * 0.1f );
if( input.IsKeyDown( sf::Key::Down ) )
particleSystem.setGravity( xgrv * 0.1f, ++ygrv * 0.1f );
if( input.IsKeyDown( sf::Key::G ) )
particleSystem.setGravity( 0.0f, 0.0f );
if( input.IsKeyDown( sf::Key::P ) )
particleSystem.setPosition( 320.0f, 240.0f );

angle += 0.1;
if( angle > 6.2832f ) angle = 0;

particleSystem.setPosition( xpos + cos( angle ) * 80, ypos + sin( angle ) * 80 );

particleSystem.remove();
particleSystem.update();
particleSystem.render();

text.SetString( particleSystem.getNumberOfParticlesString() );
window.Clear( sf::Color::Black );
window.Draw( particleSystem.getSprite() );
window.Draw( text );
window.Display();
}

return 0;
}


As you might guess, these three lines are intended to be used together:

Code: [Select]

particleSystem.remove();
particleSystem.update();
particleSystem.render();


[Groogy]

Have you posted it on the wiki?

[Lillebror]

I wouldn't mind doing so - but how do I go about it?
I looked around in the wiki but couldn't find 'create new page'.

[Edit] Solved it! Added to Sources