/// <summary>
	/// we have to use a bit of trickery in this one. The rays must be cast from a small distance inside of our
	/// collider (skinWidth) to avoid zero distance rays which will get the wrong normal. Because of this small offset
	/// we have to increase the ray distance skinWidth then remember to remove skinWidth from deltaMovement before
	/// actually moving the player
	/// </summary>
	private void moveHorizontally( ref Vector3 deltaMovement )
	{
		var isGoingRight = deltaMovement.x > 0;
		var rayDistance = Mathf.Abs( deltaMovement.x ) + _skinWidth;
		var rayDirection = isGoingRight ? Vector2.right : -Vector2.right;
		var initialRayOrigin = isGoingRight ? _raycastOrigins.bottomRight : _raycastOrigins.bottomLeft;

		for( var i = 0; i < totalHorizontalRays; i++ )
		{
			var ray = new Vector2( initialRayOrigin.x, initialRayOrigin.y + i * _verticalDistanceBetweenRays );

			DrawRay( ray, rayDirection * rayDistance, Color.red );

			// if we are grounded we will include oneWayPlatforms only on the first ray (the bottom one). this will allow us to
			// walk up sloped oneWayPlatforms
			if( i == 0 && collisionState.wasGroundedLastFrame )
				_raycastHit = Physics2D.Raycast( ray, rayDirection, rayDistance, platformMask );
			else
				_raycastHit = Physics2D.Raycast( ray, rayDirection, rayDistance, platformMask & ~oneWayPlatformMask );

			if( _raycastHit )
			{
				// the bottom ray can hit slopes but no other ray can so we have special handling for those cases
				if( i == 0 && handleHorizontalSlope( ref deltaMovement, Vector2.Angle( _raycastHit.normal, Vector2.up ) ) )
				{
					_raycastHitsThisFrame.Add( _raycastHit );
					break;
				}

				// set our new deltaMovement and recalculate the rayDistance taking it into account
				deltaMovement.x = _raycastHit.point.x - ray.x;
				rayDistance = Mathf.Abs( deltaMovement.x );

				// remember to remove the skinWidth from our deltaMovement
				if( isGoingRight )
				{
					deltaMovement.x -= _skinWidth;
					collisionState.right = true;
				}
				else
				{
					deltaMovement.x += _skinWidth;
					collisionState.left = true;
				}

				_raycastHitsThisFrame.Add( _raycastHit );

				// we add a small fudge factor for the float operations here. if our rayDistance is smaller
				// than the width + fudge bail out because we have a direct impact
				if( rayDistance < _skinWidth + kSkinWidthFloatFudgeFactor )
					break;
			}
		}
	}