Player control

I recently worked on my jumping abilities. In the beginning, I only could do double jumps. Whenever the player hits the ground he gots one extra jump which can be pretty handy and looks fun. But to jump from walls was very shaky and sometimes you had the extra jump and sometimes you didn’t because you jumped too late and used up that extra jump instead of a wall jump.

Again behavior tree

As with the weapons, it started pretty simple and straight forward by just program the player control. But for the double jump, I already had a counter in place which had to be updated and consumed. Motivated by the early success modeling weapons with a behavior tree implementation I start over the character control implementation with a behavior tree.
First I had to split my stuff into tasks to be able to model the walking and jumping behavior of the player with the libgdx-ai behavior tree

The main goals were walking, jumping, double jumps, and wall jumps. The wall jump was especially tricky.


The moving part is simple, we just apply force on the character, limit the speed to max speed and turn the character in the proper direction. The character model implementation has an update loop where it detects/measures the speed to do the walk animation properly. We apply also force to the player midair to give the player more control.

One improvement would be to let the character look in the direction he is shooting in that case he would just move forth and back but would not change the shoot direction. This is especially for fully automatic weapons.

Double jump

The double jump was just something I saw in so many games and wanted it for mine as well.

As long you jump in the same direction as you walk, I only stop midair the vertical movement to give more control else it feels very wobbly. But the horizontal movement is untouched.

In case the player also changes the direction hitting the jump button mid-air I stop completely horizontal and vertical this makes the jumps more controllable and fun. You can do all the impossible jumps you ever dreamt of.

Wall jump

If the player pushes the jump button sticking to the wall or is close enough and has no ground underneath it he gets pushed away from the wall. Actually, the push from the wall is away and slightly upward, the character also changes its direction. If you hold the movement towards the wall the jumps out and moves back to the wall and the player doesn’t change its direction. The wall jumps are unlimited. This keeps the gameplay pretty fast. The stickiness to the wall is not very strong and you have to move fast.

As soon the player jumps on a wall the vertical movement goes to a full stop. This makes the wall jumps nice and responsive. I tried it without and it feels very fluffy.

The push from the wall should make it possible to jump up a corridor with just pressing the jump button all the time without any midair movements.


The shooting part is pretty simple, it just triggers the gun. Maybe set a marker that the trigger is pulled so the player doesn’t change direction while shooting, see moving chapter above.


I’m not yet sure if I and how I want to model dashing. It’s already pretty fast. And it should do something. Maybe dodge bullets or distract enemies. This is working in progress.

Keep on testing

I do a lot of testing these days. And with the behavior tree approach, I can easily change the behavior of the controls. The downside of changing the control behavior also often means that I have to rework the levels, just think of a slightly higher jump or slightly less high jump, a tiny bit less speed, new abilities like dashing. So what’s easy still has a rat tail of other implications.

But it is fun as hell.


The jump topic is very tricky and needs by fare more testing until I can say this is it.


Software Developer

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