Create a path for NPCs

Help & Support
1

Hello guys, i am trying to add a follow path function for NPC’s but i’m doing something wrong. I explain first the whole situation. In some quest you will have a npc ally that will follow you, so when the player go more far than a given length the ally will follow him, if it’s more far than length*1.5 the npc will run after the player to catch up. But when in dungeon there will be walls, so if the npc is struck against a wall he have to follow a path to reach the player. So i have this code for the path find

pathFind: function () {
            if (this.test===1) {
                this.Root.script.gui.testpaper();
            }
            var x = this.Player.script.player.x;
            var y = this.Player.script.player.y;
            //Create a path
            if (this.path.length===0 || (this.path.length>0 && this.x===this.path[0][0] && this.y===this.path[0][1])) {
            var prevX = this.x;
            var prevY = this.y;
            this.path = this.game.pathToAFromB(x+","+y, this.x+","+this.y);
            }
            //Move towards the player
            if(this.path.length >1){
                this.dx = this.path[0][0];
                this.dy = this.path[0][1];
                
                //Don't move through closed doors
                if(!this.game.doorLocations[this.Player.script.player.depth-1][x+','+y] || !this.game.doorLocations[this.player.depth-1][x+','+y].closed){
                    if (this.x!==this.dx || this.y!==this.dy) {
                        this.dest=new pc.Vec3(this.dx,0,this.dy);
                        this.pathTo(this.dest);
                        this.startx=this.x;
                    }
                }
                this.state="path";
            }
}

then i have this line to trigger the pathfind

if ((this.state === "walking" || this.state==='run' ) && speed<0.06) {
           if (this.dx!==0 && this.dy!==0) {
                if (this.x!==this.dx || this.y!==this.dy) {
                    this.pathFind();
                }
           }
}

but something doesn’t work as it should, any idea?

2

If you are trying to implement proper path finding with obstacle avoidance, where your NPCs can navigate around your game static or dynamic objects that’s a complex subject with multiple solutions (grid based vs navmesh based).

Try searching for javascript pathfinding, usually you can get away with using a simple 2D grid even in 3D games.

Now if you are only trying to make the NPC move towards the Player in a straight line (without navigating around walls, doors etc) … you will need to calculate the path from A to B and move the NPC entity using some kind of animation. I see you have a pathToAFromB but I don’t see the implementation.

3

Hi, yes i forgot the routine AtoB since it works fine and the this.path array is properly filled, the problem is that the player don’t move alongside the path

pathToAFromB: function(a, b){
            var partsA = a.split(",");
            var xA = parseInt(partsA[0], 10);
            var yA = parseInt(partsA[1], 10);
            
            var partsB = b.split(",");
            var xB = parseInt(partsB[0], 10);
            var yB = parseInt(partsB[1], 10);
            var self=this;
            var passableCallback = function(x, y){
                return self.Root.script.Level.map[self.player.depth-1][x+","+y];
            };
            
            var astar = new ROT.Path.AStar(xA, yA, passableCallback, {topology:4});
            var path = [];
            var pathCallback = function(x, y){
                path.push([x, y]);
            };
            astar.compute(xB, yB, pathCallback);
            
            path.shift();
            return path;
        },
4

Your code isn’t compete, you are missing the actual animating method to move the entity from point to point.

Here is a good tutorial on how to do that:
https://developer.playcanvas.com/en/tutorials/camera-following-a-path

5

You are right lol Forgot a part of code completely :stuck_out_tongue: Thanks