koobas.hobune.stream
A* pathfinding for 2D top Down
So I have begun creating a 2D top down shooter and started to implement an A* AI approach. I have been reading "Unity 4.x Game AI Programming" and got their A* algorithm working correctly but the book stops once you get a Debug.DrawLine to show the path, it does not go into moving the character to each node. I was wondering if anyone could help me figure this out. I could post parts of code if anyone wants, but I think it is a very standard simple A* pathfinding algorithm. I am moving my characters right now using transform.Translate and have a method for rotating the sprite correctly. Just curious if there is a good way to go about this that I'm not aware of. I hope I'm not asking a question that has been asked a million times, I couldn't find an answer is the only reason I'm using Unity Answers. Thanks!
Vector3 directionWeShouldGo = (targetPosition - transform.position).normalized;
transform.Translate(directionWeShouldGo * Time.deltaTime);
The direction can be established with simple a - b normalized where a and b are the target position and the current position then normalized to form a direction. Just feed that into transform.Translate and voila.
Or...
You can look down the path with Quaternion.LookRotation() or transform.LookAt(targetPosition); http://docs.unity3d.com/ScriptReference/Quaternion.LookRotation.html
Then you can simply do ...
transform.Translate(Vector3.forward * Time.deltaTime);
...until you reach the destination.
Ok. I see how that would work but in my script I don't have a target position. I do have an array of the path nodes so I have been trying to make a function that starts at index 1 of the array, translate to it then iterate to the next node and so on. I have not got it working yet but Im still at it. If anyone knows a clever trick for this I would appreciate it. Thanks again
You have to get the position of the next node and use your locomotion to move towards it. $$anonymous$$eep track of which node is next with an integer (reference to the array index)
So I got him to move to the first node but then it just kind of jitters there and won't increase the index to the next node. Here is the snippet of code I am working with in Update.
int index = 1;
Node nextNode = (Node)pathArray[index];
if(transform.position.x != nextNode.position.x && transform.position.y != nextNode.position.y){
print ("Got to move to node");
Vector3 directionWeShouldGo = (nextNode.position - transform.position).normalized;
transform.Translate(directionWeShouldGo * Time.deltaTime);
} else if (transform.position.y == nextNode.position.y && transform.position.x == nextNode.position.x){
print ("increase the index");
index++;
}
Looks good, but you should never compare two positions explicitly. Try getting the distance to the next node and seeing if it is less than some reasonable threshold like 0.1 and if so then it is assumed the agent is close enough to be "at" the node.
Otherwise, the two vectors will never be the same since even a deviation of 0.000001 would return as !=.
wait Im a moron. I had int index in the update so every frame it just keeps getting reset to 1. Just put it on the class level and it works! whoohoo. now to implement rotation and resetting a new path. Thank you LaneFox for your help
Fred, Can you put your finished script here ? I'm new at progra$$anonymous$$g. If you could, you would hlp me a lot Thanks !
