Point-in-rectangle testing

Question

I have this matrix

/// as if the create a rectangle
int [][] loc = {
  {5, 15},//(x1, y1)
  {5, 30}, // (x1, y2)
  {20, 15},// (x2, y1)
  {20, 30}, // (x2, y2)
}

// this are the point that i want to check if they are in the rectangular range or not
int [] [] point = {
  {6, 16}, //(x, y)
  {3, 17}, //(x, y)
}

I want i method that can take the point and search if it in the loc range or not by using x1<x<x2 and y1<y<y2

Answer 1

A point (x, y) is inside a rectangle (x1,y1) - (x2, y2) if

(x1 <= x <= x2) and (y1 <= y <= y2)

Your code should look like this (this actually is C code, but JavaScript shouldn't be much different):

 x1 = loc[0][0];
 x2 = loc[2][0];
 y1 = loc[0][1];
 y2 = loc[2][1];
 for (int i = 0; i < num_points; i++) {
   if ((x1 <= point[i][0] <= x2) && (y2 <= point[i][1] <= y2)) {
     // This point is inside the rectangle - insert code here
   } else {
     // This point is not inside the rectangle - insert code here
   }
 }

Note that this will only work if (x1 <= x2) and (y1 <= y2), so you might perhaps make sure by using this instead the first four lines above:

x1 = Math.Min(loc[0][0], loc[2][0]);
x2 = Math.Max(loc[0][0], loc[2][0]);
y1 = Math.Min(loc[0][1], loc[2][1]);
y2 = Math.Max(loc[0][1], loc[2][1]);

Answer 2

Oh, come on.

Why don't you define what you mean by "in".

I bet if you do that, an algorithm for testing if a point is "in" naturally falls of of the definition.

We'll wait right here while you do that, ok?

Answer 3

I mean by "in" that it is within the range by using x1 < x < x2 and y1 < y < y2

Answer 4

schnaader;

Can you explain for me more a bout what you mean ?

Answer 5

Hello! but the solution presented by schnaader, is for two point (x1,y1) and (x2,y2) but we have four points in rectangle, My question for 4 points how this code will look like e.g. above code for find min of x cordinates should look like x1=math.min(x1,x2,x3,x4). am i right??