private static void circlePointImpl(int x, int y, int x0, int y0, PointPredicate op) {
op.on(x + x0, y + y0);
op.on(y + x0, x + y0);
op.on(-x + x0, y + y0);
op.on(-y + x0, x + y0);
op.on(-x + x0, -y + y0);
op.on(-y + x0, -x + y0);
op.on(x + x0, -y + y0);
op.on(y + x0, -x + y0);
}
/** Pseudo-recursive generic flood fill algorithm */
public static void fill(int x, int y, PointPredicate op) {
// using a Deque (stack) to simulate recursion
Deque<Point> points = new ArrayDeque<>();
points.push(new Point(x, y));
while (points.size() != 0) {
Point p = points.pop();
if (op.on(p.x, p.y + 1)) points.push(new Point(p.x, p.y + 1));
if (op.on(p.x, p.y - 1)) points.push(new Point(p.x, p.y - 1));
if (op.on(p.x + 1, p.y)) points.push(new Point(p.x + 1, p.y));
if (op.on(p.x - 1, p.y)) points.push(new Point(p.x - 1, p.y));
}
}
/** A version of line() that doesn't check to stop if it's reached the end point */
public static void ray(int x1, int y1, int x2, int y2, PointPredicate op) {
if (x1 == x2 && y1 == y2) return; // avoid infinite loop if starting position is ending position
int sx, sy, e2;
int dx = Math.abs(x2 - x1);
int dy =
-Math.abs(
y2 - y1); // we calculate -dx in the first place to possibly save a clock cycle down
// there
sx = x1 < x2 ? 1 : -1;
sy = y1 < y2 ? 1 : -1;
int err = dx + dy;
while (true) {
if (!op.on(x1, y1)) return;
e2 = 2 * err;
if (e2 > dy) { // down here is where I mean
err += dy;
x1 += sx;
}
if (e2 < dx) {
err += dx;
y1 += sy;
}
}
}
/**
* Traces along a line. Source:
* http://en.wikipedia.org/wiki/Bresenham's_line_algorithm#Simplification
*
* @return true if the end of the line is reached, false if it is stopped partway
*/
public static boolean line(int x1, int y1, int x2, int y2, PointPredicate op) {
int sx, sy, e2;
int dx = Math.abs(x2 - x1);
int dy =
-Math.abs(
y2 - y1); // we calculate -dx in the first place to possibly save a clock cycle down
// there
sx = x1 < x2 ? 1 : -1;
sy = y1 < y2 ? 1 : -1;
int err = dx + dy;
while (true) {
if (!op.on(x1, y1)) return false;
if (x1 == x2 && y1 == y2) return true;
e2 = 2 * err;
if (e2 > dy) { // down here is where I mean
err += dy;
x1 += sx;
}
if (e2 < dx) {
err += dx;
y1 += sy;
}
}
}
