this.res = 10;

  this.flowField = [];

  this.cols = wid/this.res;

  this.rows = hit/this.res;

  var xoff = 0;

  for(i=0;i<this.cols;i++){

    var yoff = 0;

    this.flowField[i] = [];

    for(j=0;j<this.rows;j++){

      var theta = map(noise(xoff,yoff),0,1,0,TWO_PI);

      this.flowField[i][j] = createVector(cos(theta),sin(theta));

      yoff += 0.1; 

    }

    xoff += 0.1;

  }

}

​

FlowField.prototype.lookup = function(location){

  var col = round(constrain(location.x/this.res,0,this.cols+1));

  var row = round(constrain(location.y/this.res,0,this.rows+1));

  return this.flowField[col][row];

}

​