Particle Emitters - Part II

Check out the Particle Emitters Series to get the full picture.

There are some basic functions that are needed for to make this work, they are as follows. We won't be modify this much except for the plotParticles function, where we have to change the if statements for each of our effects. (I know there must be a clever way to do this, but I ran outta time)


function Particle(point, velocity, acceleration,color,size) {
  this.position = point || new Vector(0, 0);
  this.velocity = velocity || new Vector(0, 0);
  this.acceleration = acceleration || new Vector(0, 0);
  this.origin = new Vector(0,0);
  this.color = color
  this.particleSize = size;
  this.action = "";
  this.life = 0;
  this.tether = 0;
  this.radius = 25;
}

function plotParticles(boundsX, boundsY)
{
    // a new array to hold particles within our bounds
    var currentParticles = [];

    for (var i = 0; i < particles.length; i++)
    {
        var particle = particles[i];

       
        var pos = particle.position;

               
        if(particle.action == "warpParticle")
        {
            particle = warpParticle(particle);
            particle.move();
        }

        if(particle.action == "whirlParticle")
        {
            particle = whirlParticle(particle);
        }
       
        if(particle.action == "beamParticle")
        {
            particle = beamParticle(particle);
        }
       
       
        if(particle != "")
        {
            // If we're out of bounds, drop this particle and move on to the next
            if (pos.x < 0 || pos.x > boundsX || pos.y < 0 || pos.y > boundsY) continue;
            if (particle.particleSize <= 0) continue;

           
            // Add this particle to the list of current particles
            currentParticles.push(particle);
        }
    }

    // Update our global particles, clearing room for old particles to be collected
    particles = currentParticles;
}



function rand(from,to)
{
    return Math.floor(Math.random()*(to-from+1)+from);
}


function drawParticles()
{
    // For each particle
    for (var i = 0; i < particles.length; i++)
    {
        context.fillStyle = particles[i].color;
        var position = particles[i].position;
        //context.fillRect(position.x, position.y, particles[i].particleSize, particles[i].particleSize);

        context.fillStyle = particles[i].particleColor;
        context.beginPath();
        context.arc(position.x, position.y, particles[i].particleSize, 0, Math.PI * 2);
        context.closePath();
        context.fill();

    }
}


function addNewParticles()
{
    for (var i = 0; i < emitters.length; i++)
    {
        if(emitters[i].numParticles < emitters[i].maxParticles)
        {
            for (var j = 0; j < emitters[i].emissionRate; j++)
            {
                particles.push(emitters[i].emit());
                emitters[i].numParticles++;
            }
        }

    }
}



Particle.prototype.move = function () {
  // Add our current acceleration to our current velocity
  this.velocity.add(this.acceleration);

  // Add our current velocity to our position
  this.position.add(this.velocity);
};



function Vector(x, y) {
  this.x = x || 0;
  this.y = y || 0;
}

// Add a vector to another
Vector.prototype.add = function(vector) {
  this.x += vector.x;
  this.y += vector.y;
}

// Gets the length of the vector
Vector.prototype.getMagnitude = function () {
  return Math.sqrt(this.x * this.x + this.y * this.y);
};

// Gets the angle accounting for the quadrant we're in
Vector.prototype.getAngle = function () {
  return Math.atan2(this.y,this.x);
};

// Allows us to get a new vector from angle and magnitude
Vector.fromAngle = function (angle, magnitude) {
  return new Vector(magnitude * Math.cos(angle), magnitude * Math.sin(angle));
};