@woosh/meep-engine/src/core/graph/metis/mesh_to_metis_graph.js

Pure JavaScript game engine. Fully featured and production ready.

import { assert } from "../../assert.js";

/**
 * @param {TopoTriangle[]} face_array
 * @returns {{edge_addresses:Uint32Array, adjacency:Uint32Array, edge_weights:Uint32Array}}
 */
export function mesh_to_metis_graph(face_array) {
    assert.isArray(face_array, 'face_array');

    const input_face_count = face_array.length;

    const edge_addresses = new Uint32Array(input_face_count + 1);
    const adjacency = [];
    const edge_weights = [];

    const face_index_map = new Map();

    for (let i = 0; i < input_face_count; i++) {
        const face = face_array[i];
        face_index_map.set(face, i);
    }

    let offset = 0;
    edge_addresses[0] = 0;
    for (let i = 0; i < input_face_count; i++) {
        const face = face_array[i];

        const edges = face.edges;

        const edge_count = edges.length;
        for (let j = 0; j < edge_count; j++) {
            const topoEdge = edges[j];

            const edge_faces = topoEdge.faces;

            const edge_face_count = edge_faces.length;
            for (let k = 0; k < edge_face_count; k++) {
                const neighbour = edge_faces[k];

                if (neighbour === face) {
                    //skip self
                    continue;
                }

                adjacency[offset] = face_index_map.get(neighbour);
                edge_weights[offset] = 1;

                offset++;
            }
        }

        edge_addresses[i + 1] = offset;
    }

    const adjecency_uint32 = new Uint32Array(adjacency);
    const edge_weights_uint32 = new Uint32Array(edge_weights);


    return {
        edge_addresses: edge_addresses,
        adjacency: adjecency_uint32,
        edge_weights: edge_weights_uint32
    };
}