CODEWITHSUNDEEP
javaartificial-intelligencegame-physics
Tohmas
Tohmas

Reputation: 547

Implementing AI to hide behind obstacles

I am developing an AI simulation of predator and prey. I would like to simulate the AI hiding behind obstacles, if it is being chased. But I am still trying to figure out the best way to implement this.

I was thinking along the lines of checking on which side of the obstacle the predator is on and trying to go on the opposite side. Maybe using the A* path finding algorithm to ensure that it gets there using the shortest path.

Now the main reason I am writing is in case somebody is able to point me in the right direction of implementing this (maybe somebody has done this before) or have any other good ideas how to implement it. I have never done anything like this before in terms of programming AI or making any game.

All the obstacles are either horizontal or vertical squares/rectangles.

enter image description here

Please note that the circle in red is the predator while the circle in green is the prey being chased.

Upvotes: 1

Views: 251

Answers (2)

user1497579
user1497579

Reputation:

I can't give any code off the top of my head, but I can tell you a few things:

First, you need to define the goal of this program. For this case, it is to get the AI to hide behind an obstacle, keeping the user and the AI on opposite sides whenever possible.

Next, you need to decide what needs to be done inside the code (without writing any real code) to accomplish this goal. For instance:

  • We need to determine what "zone" of the scene is considered "behind the obstacle"
  • Next, we need to determine a path for the AI to get to that zone without going through the obstacle.
  • Lastly, we need to add some sort of delay to this so the AI doesn't constantly change its mind for every pixel the user moves across the screen

This isn't per se an easy problem, but it is certainly achievable without breaking too much of a sweat. I'd recommend you find a way, even if it is slow and requires a ton of code, then write the code for it, and lastly refine. If you worry about refinement, then you never get any of the problem solved.

HINT: Determine a vector that points from the player to the middle of the obstacle. Then, multiply the vector by 2 and add it to the position of the player and that gives you a point on the other side of the obstacle (assuming it is a rectangle). Apply a Math.min() or Math.max() restrictor to the x and y values you get to keep the AI as close or far from the obstacle as you wish. That should be a decent start! :)

Update -- I decided to add some code!

// This assumes a few variables:
int obstacleCenterX, obstacleCenterY;
int aiX, aiY, aiWalkSpeed;
int predatorX, predatorY;
private void updateAIMovement() {
    int slope_x = obstacleCenterX - predatorX;
    int slope_y = obstacleCenterY - predatorY;
    int destination_x = predatorX + (slope_x * 2);
    int destination_y = predatorY + (slope_y * 2);
    if(aiX != destination_x){
        aiX += (slope_x / Math.abs(slope_x)) * aiWalkSpeed;
    }
    if(aiY != destination_y){
        aiY += (slope_y / Math.abs(slope_y)) * aiWalkSpeed;
    }
}

I have not tested anything at all, but I think this might be somewhat of a right path to take. I could have done A LOT to improve just that little code snippet, but I didn't (such as some trig to make sure the player moves at a true speed when going diagonally, etc...)

Hopefully this helps a little!

Upvotes: 1

MrSmith42
MrSmith42

Reputation: 10151

I would check if there is something crossing the direct line between x and each observer. If it is, x is hidden.

Upvotes: 0

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