Method triArea2

packages/pathfinding/src/navmesh/NavMesh.ts:560–562

* @zh 计算三角形面积的两倍（用于判断点的相对位置） * @en Calculate twice the triangle area (for point relative position)

(a: IPoint, b: IPoint, c: IPoint)

     * @en Calculate twice the triangle area (for point relative position)
     */
    private triArea2(a: IPoint, b: IPoint, c: IPoint): number {
        return (c.x - a.x) * (b.y - a.y) - (b.x - a.x) * (c.y - a.y);
    }

    /**
     * @zh 计算路径总长度