function Particle(point,velocity){
	this.position     = point;
   this.velocity     = velocity;
	this.acceleration = new Vector(0,0);
	this.ttl          = -1;
	this.lived        = 0;
}

Particle.GLOBAL_DRAW_COLOR = [66,167,222,255];
//Particle.GLOBAL_DRAW_COLOR = [166,67,0,255];

Particle.prototype.submitToFields = function(fields) {
   var totalAccelerationX = 0;
   var totalAccelerationY = 0;
   
   for (var i = 0; i < fields.length; i++) {
      var field = fields[i];

      // inlining what should be Vector object methods for performance reasons
      var vectorX = field.position.x - this.position.x;
      var vectorY = field.position.y - this.position.y;
      var force = field.mass / Math.pow((vectorX*vectorX+field.mass/2+vectorY*vectorY+field.mass/2),1.5); 
      totalAccelerationX += vectorX * force;
      totalAccelerationY += vectorY * force;
   }
   this.acceleration = new Vector(totalAccelerationX,totalAccelerationY);
};

Particle.prototype.move = function() {
   this.velocity.x += this.acceleration.x;
   this.velocity.y += this.acceleration.y;
   this.position.x += this.velocity.x;
   this.position.y += this.velocity.y;
};

Particle.prototype.drawVariable = function(pixels,width,height) {
   var baseIndex = 4 * (~~this.position.y * width + ~~this.position.x);
   var velocity = this.velocity.getMagnitude();
   var r = Particle.GLOBAL_DRAW_COLOR[0] * velocity;
   var g = Particle.GLOBAL_DRAW_COLOR[1];
   var b = Particle.GLOBAL_DRAW_COLOR[2] * .5/velocity;
   var a = Particle.GLOBAL_DRAW_COLOR[3];
   pixels[baseIndex]      += r;
   pixels[baseIndex + 1]  += g;
   pixels[baseIndex + 2]  += b;
   pixels[baseIndex + 3]   = a;
}

Particle.prototype.drawBasic = function(pixels,width,height) {
   var baseIndex = 4 * (~~this.position.y * width + ~~this.position.x);
   var r = Particle.GLOBAL_DRAW_COLOR[0];
   var g = Particle.GLOBAL_DRAW_COLOR[1];
   var b = Particle.GLOBAL_DRAW_COLOR[2];
   var a = Particle.GLOBAL_DRAW_COLOR[3];
   pixels[baseIndex]      += r;
   pixels[baseIndex + 1]  += g;
   pixels[baseIndex + 2]  += b;
   pixels[baseIndex + 3]   = a;
}

Particle.prototype.drawSoft = function(pixels,width,height) {
   var baseIndex = 4 * (~~this.position.y * width + ~~this.position.x);
   var r = Particle.GLOBAL_DRAW_COLOR[0];
   var g = Particle.GLOBAL_DRAW_COLOR[1];
   var b = Particle.GLOBAL_DRAW_COLOR[2];
   var a = Particle.GLOBAL_DRAW_COLOR[3];
   pixels[baseIndex - 4]  += r*.80;
   pixels[baseIndex - 3]  += g*.80;
   pixels[baseIndex - 2]  += b*.80;
   pixels[baseIndex - 1]   = a;
   pixels[baseIndex]      += r*.80;
   pixels[baseIndex + 1]  += g*.80;
   pixels[baseIndex + 2]  += b*.80;
   pixels[baseIndex + 3]   = a;
   pixels[baseIndex + 4]  += r*.80;
   pixels[baseIndex + 5]  += g*.80;
   pixels[baseIndex + 6]  += b*.80;
   pixels[baseIndex + 7]   = a;
   baseIndex += width * 4;
   pixels[baseIndex - 4]  += r*.80;
   pixels[baseIndex - 3]  += g*.80;
   pixels[baseIndex - 2]  += b*.80;
   pixels[baseIndex - 1]   = a;
   pixels[baseIndex]      += r;
   pixels[baseIndex + 1]  += g;
   pixels[baseIndex + 2]  += b;
   pixels[baseIndex + 3]   = a;
   pixels[baseIndex + 4]  += r*.80;
   pixels[baseIndex + 5]  += g*.80;
   pixels[baseIndex + 6]  += b*.80;
   pixels[baseIndex + 7]   = a;
   baseIndex += width * 4;
   pixels[baseIndex - 4]  += r*.80;
   pixels[baseIndex - 3]  += g*.80;
   pixels[baseIndex - 2]  += b*.80;
   pixels[baseIndex - 1]   = a;
   pixels[baseIndex]      += r*.80;
   pixels[baseIndex + 1]  += g*.80;
   pixels[baseIndex + 2]  += b*.80;
   pixels[baseIndex + 3]   = a;
   pixels[baseIndex + 4]  += r*.80;
   pixels[baseIndex + 5]  += g*.80;
   pixels[baseIndex + 6]  += b*.80;
   pixels[baseIndex + 7]   = a;
}

Particle.prototype.draw = Particle.prototype.drawBasic;