如何让SDL2 0,0在渲染时定位窗口的中心？

#include <SDL2/SDL.h>

int main(int argc, char* argv[]) {
    SDL_Init(SDL_INIT_VIDEO);

    int windowWidth = 800;
    int windowHeight = 600;

    SDL_Window *window = SDL_CreateWindow("SDL2 Window",
                                         SDL_WINDOWPOS_CENTERED,
                                         SDL_WINDOWPOS_CENTERED,
                                         windowWidth,
                                         windowHeight,
                                         SDL_WINDOW_SHOWN);

    SDL_Renderer *renderer = SDL_CreateRenderer(window, -1, SDL_RENDERER_ACCELERATED);

    // 确保SDL_SetRenderDrawColor设置了颜色
    SDL_SetRenderDrawColor(renderer, 0, 0, 0, 255);
    SDL_RenderClear(renderer);

    int centerX = windowWidth / 2;
    int centerY = windowHeight / 2;

    // 假设您要绘制一个圆心位于屏幕中心的圆，半径为50
    int radius = 50;

    // 设置绘制颜色，例如红色
    SDL_SetRenderDrawColor(renderer, 255, 0, 0, 255);

    // 绘制圆的轮廓
    for (int w = 0; w < radius*2; w++) {
        for (int h = 0; h < radius*2; h++) {
            int dx = radius - w; // horizontal offset
            int dy = radius - h; // vertical offset
            if ((dx*dx + dy*dy) <= (radius * radius)) {
                SDL_RenderDrawPoint(renderer, centerX + dx, centerY + dy);
            }
        }
    }

    SDL_RenderPresent(renderer);

    // 在此处添加您的事件循环和其他逻辑

    SDL_Delay(3000); // 仅用于演示目的，在3秒后关闭窗口

    SDL_DestroyRenderer(renderer);
    SDL_DestroyWindow(window);
    SDL_Quit();

    return 0;
}