/*
Axis‑aligned rectangles are simply rectangles whose edges are parallel to the
coordinate axes — meaning their sides are horizontal and vertical.
That single assumption makes the overlap test dramatically simpler and faster.
*/
/*
Rectangle overlap detection (axis-aligned)
Each rectangle is defined by:
- x, y : coordinates of its top-left corner
- w, h : width and height
Two rectangles DO NOT overlap if any separating condition is true:
- One is completely to the left of the other
- One is completely to the right of the other
- One is completely above the other
- One is completely below the other
Otherwise, they overlap.
This is the standard O(1) test for axis-aligned rectangles.
*/
struct Rect {
x: f64, // top-left X
y: f64, // top-left Y
w: f64, // width
h: f64, // height
}
/*
Returns true if rectangles A and B overlap.
*/
fn rectangles_overlap(a: &Rect, b: &Rect) -> bool {
// Compute edges of A
let a_left: f64 = a.x;
let a_right: f64 = a.x + a.w;
let a_top: f64 = a.y;
let a_bottom: f64 = a.y + a.h;
// Compute edges of B
let b_left: f64 = b.x;
let b_right: f64 = b.x + b.w;
let b_top: f64 = b.y;
let b_bottom: f64 = b.y + b.h;
// Separating conditions:
if a_right <= b_left { return false; } // A is left of B
if b_right <= a_left { return false; } // B is left of A
if a_bottom <= b_top { return false; } // A is above B
if b_bottom <= a_top { return false; } // B is above A
true // Otherwise, they overlap
}
fn main() {
let a = Rect { x: 10.0, y: 10.0, w: 30.0, h: 20.0 }; // Example rectangle A
let b = Rect { x: 25.0, y: 15.0, w: 40.0, h: 25.0 }; // Overlaps A
let c = Rect { x: 100.0, y: 100.0, w: 10.0, h: 10.0 }; // Does not overlap A
println!("A vs B overlap? {}", if rectangles_overlap(&a, &b) { "YES" } else { "NO" });
println!("A vs C overlap? {}", if rectangles_overlap(&a, &c) { "YES" } else { "NO" });
}
/*
run:
A vs B overlap? YES
A vs C overlap? NO
*/
