Function forceLayout

src/chart/graph/forceHelper.ts:74–227

(
    inNodes: N[],
    inEdges: E[],
    opts: LayoutCfg
)

// }

export function forceLayout<N extends InputNode, E extends InputEdge>(
    inNodes: N[],
    inEdges: E[],
    opts: LayoutCfg
) {
    const nodes = inNodes as LayoutNode[];
    const edges = inEdges as LayoutEdge[];
    const rect = opts.rect;
    const width = rect.width;
    const height = rect.height;
    const center = [rect.x + width / 2, rect.y + height / 2];
    // let scale = opts.scale || 1;
    const gravity = opts.gravity == null ? 0.1 : opts.gravity;

    // for (let i = 0; i < edges.length; i++) {
    //     let e = edges[i];
    //     let n1 = e.n1;
    //     let n2 = e.n2;
    //     n1.edges = n1.edges || [];
    //     n2.edges = n2.edges || [];
    //     n1.edges.push(e);
    //     n2.edges.push(e);
    // }
    // Init position
    for (let i = 0; i < nodes.length; i++) {
        const n = nodes[i] as LayoutNode;
        if (!n.p) {
            n.p = vec2.create(
                width * (Math.random() - 0.5) + center[0],
                height * (Math.random() - 0.5) + center[1]
            );
        }
        n.pp = vec2.clone(n.p);
        n.edges = null;
    }

    // Formula in 'Graph Drawing by Force-directed Placement'
    // let k = scale * Math.sqrt(width * height / nodes.length);
    // let k2 = k * k;

    const initialFriction = opts.friction == null ? 0.6 : opts.friction;
    let friction = initialFriction;

    let beforeStepCallback: (nodes: N[], edges: E[]) => void;
    let afterStepCallback: (nodes: N[], edges: E[], finished: boolean) => void;

    return {
        warmUp: function () {
            friction = initialFriction * 0.8;
        },

        setFixed: function (idx: number) {
            nodes[idx].fixed = true;
        },

        setUnfixed: function (idx: number) {
            nodes[idx].fixed = false;
        },