画线在SDL2 C++中闪烁。如何修改我的游戏循环？

#include <SDL.h>

int main(int argc, char* argv[]) {
    // 初始化SDL
    SDL_Init(SDL_INIT_VIDEO);

    // 创建窗口和渲染器
    SDL_Window* window = SDL_CreateWindow("My Game", SDL_WINDOWPOS_UNDEFINED, SDL_WINDOWPOS_UNDEFINED, 800, 600, SDL_WINDOW_SHOWN);
    SDL_Renderer* renderer = SDL_CreateRenderer(window, -1, SDL_RENDERER_ACCELERATED);

    // 游戏循环标志
    bool isRunning = true;

    // 闪烁标志
    bool isFlashing = false;

    // 闪烁计时器
    int flashTimer = 0;

    // 游戏循环
    while (isRunning) {
        // 处理事件
        SDL_Event event;
        while (SDL_PollEvent(&event)) {
            if (event.type == SDL_QUIT) {
                isRunning = false;
            }
        }

        // 清空渲染器
        SDL_SetRenderDrawColor(renderer, 0, 0, 0, 255);
        SDL_RenderClear(renderer);

        // 画线
        if (isFlashing) {
            SDL_SetRenderDrawColor(renderer, 255, 255, 255, 255);
        } else {
            SDL_SetRenderDrawColor(renderer, 0, 0, 0, 255);
        }
        SDL_RenderDrawLine(renderer, 0, 0, 800, 600);

        // 更新渲染器
        SDL_RenderPresent(renderer);

        // 闪烁逻辑
        flashTimer++;
        if (flashTimer >= 60) {
            isFlashing = !isFlashing;
            flashTimer = 0;
        }
    }

    // 清理SDL资源
    SDL_DestroyRenderer(renderer);
    SDL_DestroyWindow(window);
    SDL_Quit();

    return 0;
}