Distance

FlxMath offers several helper functions check the distance between an object and a {$ flixel.math.FlxPoint %}, the mouse, a touch, or another object.

Use distanceToMouse, distanceToPoint, distanceToTouch, and distanceBetween to get the distance in pixels between your object and the relevant item.

// get the distance between your target and a FlxPoint
distance = FlxVelocity.distanceToPoint(target, point);
Note: Use the related `isDistanceTo*Within` functions if you just want to check if the distance is within a specific value. These functions avoid the expensive `Math.sqrt` call that is used in the other functions.

Demonstration

Source

View Source on GitHub 

package;

import flixel.FlxG;
import flixel.FlxSprite;
import flixel.FlxState;
import flixel.math.FlxMath;

class PlayState extends FlxState
{
	var sprite:FlxSprite;
	var box:FlxSprite;
	var inRange:Bool;

	override public function create()
	{
		bgColor = 0;

		super.create();

		box = new FlxSprite("assets/bigbox.png");
		box.centerOrigin();
		box.screenCenter();
		add(box);

		sprite = new FlxSprite("assets/sprite.png");
		sprite.centerOrigin();
		sprite.y = FlxG.height / 2 - sprite.height / 2;
		sprite.velocity.x = 100;
		add(sprite);
	}

	override public function update(elapsed:Float)
	{
		if ((sprite.velocity.x > 0 && sprite.x >= FlxG.width - sprite.width)
			|| (sprite.velocity.x < 0 && sprite.x <= 0))
		{
			sprite.velocity.x *= -1;
		}

		inRange = false;
		inRange = FlxMath.isDistanceWithin(sprite, box, 100);
		box.alpha = inRange ? 0.5 : 1;

		super.update(elapsed);
	}
}