Method update

packages/fairygui/src/ecs/FGUIRenderSystem.ts:140–171

* Update all FGUI components * 更新所有 FGUI 组件

(deltaTime?: number)

     * 更新所有 FGUI 组件
     */
    public update(deltaTime?: number): void {
        if (!this._enabled) return;

        // Calculate delta time in seconds if not provided
        const currentTime = performance.now() / 1000;
        const dt = deltaTime ?? (currentTime - this._lastTime);
        this._lastTime = currentTime;

        // Update timers - Timer expects milliseconds
        Timer.inst.update(dt * 1000);

        // Clear collector for new frame
        this._collector.clear();

        // Sort components by sorting order
        const sortedComponents = Array.from(this._components)
            .filter(c => c.isReady && c.visible)
            .sort((a, b) => a.sortingOrder - b.sortingOrder);

        // Collect render data from each component
        for (const component of sortedComponents) {
            if (component.root) {
                component.syncProperties();
                component.root.collectRenderData(this._collector);
            }
        }

        // Submit render data
        if (this._onSubmit) {
            this._onSubmit(this._collector);
        }
    }

    /**
     * Dispose the system