php find distance of a point and a line segment not a line in 2D

Question

I have two point of a line like p1(a,b) and p2(c,d) my point is X(x,y)

I've searched and find like here

but it isn't php can anyone help me

Bradfield

Answer 1

DISCLAIMER: I assumed the JS code from the linked answer works.

Below is my attempt to convert the javascript code from here to PHP.

function sqr($x) { return $x * $x; }
function dist2($v, $w) { return sqr($v->x - $w->x) + sqr($v->y - $w->y); }
function distToSegmentSquared($p, $v, $w) {
    $l2 = dist2($v, $w);
    if ($l2 == 0) return dist2($p, $v);
    $t = (($p->x - $v->x) * ($w->x - $v->x) + ($p->y - $v->y) * ($w->y - $v->y)) / $l2;
    $t = max(0, min(1, $t));
    return dist2($p, (object) array('x' => $v->x + $t * ($w->x - $v->x),
                    'y' => $v->y + $t * ($w->y - $v->y) ));
}
function distToSegment($p, $v, $w) { return sqrt(distToSegmentSquared($p, $v, $w)); }

Use it like so:

$p = (object) array('x' => 2, 'y' => 2);
$v = (object) array('x' => 9, 'y' => 2);
$w = (object) array('x' => 2, 'y' => 9);

echo distToSegment($p, $v, $w);

---

---

Comparing JS output with PHP output:

TEST 1

For

x = {x:2, y:2}
v = {x:9, y:2}
w = {x:2, y:9}

JS OUTPUT:

4.949747468305833

PHP OUTPUT:

4.9497474683058

---

TEST 2

For

x = {x:1, y:9}
v = {x:4, y:4}
w = {x:4, y:9}

JS OUTPUT:

3

PHP OUTPUT:

3

---

TEST 3

For

x = {x:5, y:6}
v = {x:2, y:9}
w = {x:8, y:2}

JS OUTPUT:

0.32539568672798375

PHP OUTPUT:

0.32539568672798

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