Empowerment: Sliding Ninjas - The Game Maker's Companion: Game Development - page 84

Wall Polish
We're going to need to make some serious improvements to the climbing mechanic before it's as
slick as Zool's movement on land and in the air. For a start, it's really easy to grab onto a wall, but
a bit of a pain getting detached again. He appears to cling on to thin air at the top or bottom of
walls and you're forced to jump off awkwardly in order to get free. It's also annoying when he
accidently slides into a wall while walking in one direction, but then is forced to jump off again
before he can walk back in the other. These are all fairly minor issues to fix, but will drastically
improve the responsiveness of Zool's controls. They will involve a few changes to the keyboard
events, so we'll begin with those.

Improving Detachment for the Zool Wall State Object
1.

Reopen obj_zool_wall and select the Keyboard, Down event. Include an Else action
( control tab) at the end of the actions list. This adds a separate condition for when Zool
is climbing down and there is no longer an obj_wall below and in front of him.

2. Include a Start Block action. It's not strictly necessary, as we will only be including one

action, but it looks neatest as we used a block further above.

Include a Change Instance action ( main1 tab) that will change into obj_zool_air and
Perform Events ( Destroy and Create ) as it does so.

3.

4. Include an End Block action ( control tab).

5. Now select the Keyboard, Up event. Edit the Check Object action ( control tab) that

checks for the Object obj_wall and change the Y setting from -4 to -22 . We know
from earlier that Zool's bounding box extends 18 pixels above his origin and that he
climbs at 4 pixels per step. Therefore, this test will make sure that Zool only moves
up if his bounding box would not extend beyond the top of the wall after moving (see
Figure 4-11).