If you are trying to draw it to an image, you can use a queue-based flood-filling algorithm.
Voronoi::draw(){
// define colors for each point in the diagram;
// make a structure to hold {pixelCoords,sourcePoint} queue objects
// initialize a struct of two closest points for each pixel on the map
// initialize an empty queue;
// for each point in diagram:
// for the push object, first set the pixelCoords to pixel coordinates of point;
// set the sourcePoint of the push object to the current point;
// push the queue object;
// while queue is not empty:
// dequeue a queue object;
// step through cardinal neighbors n,s,e,w:
// if the current dequeued source point is closer to the neighboring pixel than either of the two closest:
// set a boolean doSortAndPush to false;
// if only one close neighbor is set:
// add sourcePoint to closestNeighbors for pixel;
// set doSortAndPush to true;
// elif sourcePoint is closer to pixel than it's current close neighbor points:
// replace the furthest neighbor point with sourcePoint;
// set doSortAndPush to true;
// if flag doSortAndPush is true:
// re-sort closest neighbors;
// enqueue object made of neighbor pixel coordinates and sourcePoint;
// for each pixel location:
// if distance to closest point within a radius for point drawing:
// color pixel the point color;
// elif distances to the two closest neighbors are roughly equal:
// color the pixel to your border color;
// else
// color the pixel the color of the point's region;
}
Using a queue will ensure that regions spread in parallel, minimizing total number of pixel visits. If you use a stack the first point will fill the whole image, then the second will fill any pixels closer to it than the first point. This will continue, greatly increasing visit counts. Using a FIFO queue processes pixels in the order that they are pushed. The resulting images will be roughly the same whether you use stack or queue, but the big-O for queue is far closer to linear (in relation to number of image pixels) than the stack algoritm's big-O. The general idea is that the regions will spread at the same rate and collisions will generally happen exactly at points that correspond to region boundaries.
