@nichathan-gaming/map-generator/mapGenerator/primsGenerator/primsGenerator.js

Creates and generates a 2 dimensional array with various path generation functions.

import countNeighbors from "../helpers/countNeighbors.js";
import getNewIndexes from "./getNewIndexes.js";
import mapGenerator from "../mapGenerator.js";
import assertIndex from "../helpers/assertIndex.js";
import {assertInstanceOf, assertType, basicTypes} from '@nichathan-gaming/assertions';

/**
 * Generates a path through the map 
 * using Prim's algorithm : Wikipedia Link : https://en.wikipedia.org/wiki/Prim%27s_algorithm
 * @param {mapGenerator} map The current game map element
 * @param {number} maxPathSize The maximum size for the path
 * @param {[number, number]} startIndex The index that the path begins at
 */
const primsGenerator = (map, maxPathSize, startIndex) => {
    assertInstanceOf(map, mapGenerator);
    assertType(maxPathSize, basicTypes.number);
    assertIndex(startIndex);

    //get the walkable value
    const baseValue = map.getWalkableValue();

    //set the startIndex
    map.setWalkableValueAtIndex(startIndex);

    //initialize the map locations to path along
    const mapLocations = getNewIndexes(map, [0, 0], [], baseValue);

    while(mapLocations.length){
        //get the next index
        const nextIndex = mapLocations.splice(0, 1)[0];

        //check the number of neighbors
        const neighborCount = countNeighbors(map, 1, nextIndex, baseValue, false);

        if(neighborCount <= maxPathSize){
            //the index is valid, set it as a path
            map.setWalkableValueAtIndex(nextIndex);

            //add new locations to the beginning of mapLocations based on this index
            mapLocations.unshift(...getNewIndexes(map, nextIndex, mapLocations, baseValue));
        };
    };
};

export default primsGenerator;