float[] xcircle;
float[] ycircle;

void setup () 
{
    size( 200, 200 );
    int circlesteps = 6;
    xcircle = new float[360/circlesteps];
    ycircle = new float[360/circlesteps];
    
    for ( int i = 0; i<xcircle.length; i++ )
    {
	  xcircle[i] = sin(radians(i*circlesteps));
	  ycircle[i] = cos(radians(i*circlesteps));
    }   
}

int percCounter = 1;

void draw()
{
    background(125);
    translate(width/2, height/2);

    drawLoop(50,percCounter);
    percCounter++;
    percCounter %= 101;
}

void drawLoop (float rad, float perc)
{
    int steps = floor((xcircle.length/100.0) * perc);
    beginShape();
	  for( int i=0; i<steps; i++ )
	  {
		vertex(rad*xcircle[i],rad*ycircle[i]);
	  }
    endShape(CLOSE);
}