HaxePunk/HaxePunk

package platformer.entities;

import flash.geom.Point;
import haxepunk.HXP;
import haxepunk.Entity;
import haxepunk.math.MathUtil;

class Physics extends Entity
{

    // Define variables
    public var velocity:Point;
    public var acceleration:Point;
    public var friction:Point;
    public var maxVelocity:Point;
    public var gravity:Point;

    public static var solid:String = "solid";

    public function new(x:Float, y:Float)
    {
        super(x, y);
        _onGround = false;

        velocity     = new Point();
        acceleration = new Point();
        friction     = new Point();
        maxVelocity  = new Point();
        gravity      = new Point();
    }

    public var onGround(get_onGround, null): Bool;
    function get_onGround():Bool { return _onGround; }

    override public function update()
    {
        // Apply acceleration and velocity
        velocity.x += acceleration.x;
        velocity.y += acceleration.y;
        applyVelocity();
        applyGravity();
        checkMaxVelocity();
        super.update();
    }

    public function applyGravity()
    {
        //increase velocity based on gravity
        velocity.x += gravity.x;
        velocity.y += gravity.y;
    }

    function checkMaxVelocity()
    {
        if (maxVelocity.x > 0 && Math.abs(velocity.x) > maxVelocity.x)
        {
            velocity.x = maxVelocity.x * MathUtil.sign(velocity.x);
        }

        if (maxVelocity.y > 0 && Math.abs(velocity.y) > maxVelocity.y)
        {
            velocity.y = maxVelocity.y * MathUtil.sign(velocity.y);
        }
    }

    override public function moveCollideY(e:Entity):Bool
    {
        if (velocity.y * MathUtil.sign(gravity.y) > 0)
        {
            _onGround = true;
        }
        velocity.y = 0;

        velocity.x *= friction.x;
        if (Math.abs(velocity.x) < 0.5) velocity.x = 0;
        return true;
    }

    override public function moveCollideX(e:Entity):Bool
    {
        velocity.x = 0;

        velocity.y *= friction.y;
        if (Math.abs(velocity.y) < 1) velocity.y = 0;
        return true;
    }

    function applyVelocity()
    {
        var i:Int;

        _onGround = false;

        moveBy(velocity.x, velocity.y, solid, true);
    }

    var _onGround:Bool;

}