After I published my first solution I got feedback that the same can be achieved calculating other way. So I tried implement another way:
Is it faster?
I did two tests:
1. I took solution 1 and 2 gave them the same data (line is not horizontal/vertical and point is not on the line) - solution 1 was 10-15% faster.
2. I add the same checking (the line is vertical/horizontal or point is on the line) to solution 1 and repeated test - both solution were performing almost identically.
public double distanceBetweenLineAndPoints(Point a, Point b, Point c){
double dx = a.x - b.x;
double dy = a.y - b.y;
if(dy == 0){
//we have vertical line
return distanceBetweenPoints(new Point(c.x, a.y), c);
}
if(dx == 0){
//we have horizontal line
return distanceBetweenPoints(new Point(a.x, c.y), c);
}
double slope = dy / dx;
//lets check - may be c point is on the line
if(c.y - a.y == slope * (c.x - a.x)){
//yes, it is
return 0;
}
Point aa = new Point();
Point bb = new Point();
aa.x = c.x;
aa.y = slope * (c.x - a.x)+ a.y;
bb.x = (c.y - a.y)/slope + a.x;
bb.y = c.y;
return (distanceBetweenPoints(bb, c) / distanceBetweenPoints(aa, bb)) *
distanceBetweenPoints(aa, c);
}
Is it faster?
I did two tests:
1. I took solution 1 and 2 gave them the same data (line is not horizontal/vertical and point is not on the line) - solution 1 was 10-15% faster.
2. I add the same checking (the line is vertical/horizontal or point is on the line) to solution 1 and repeated test - both solution were performing almost identically.
