问来自IMG_Load()的SDL_Texture无法绘制？

EN

#include <SDL.h>
#include <SDL_Image.h>

int main(int argc,char* args[]) {
    SDL_Init(SDL_INIT_EVERYTHING);
    IMG_Init(IMG_INIT_PNG);
    SDL_Window* window = SDL_CreateWindow("_", SDL_WINDOWPOS_CENTERED, SDL_WINDOWPOS_CENTERED, 640, 480, SDL_WINDOW_SHOWN);
    SDL_Renderer* render = SDL_CreateRenderer(window, -1, SDL_RENDERER_ACCELERATED);
    SDL_SetRenderDrawColor(render,0, 255, 255, 255);
    SDL_Surface* img = IMG_Load("circle.png");
    SDL_Texture* texture = SDL_CreateTextureFromSurface(render, img);
    SDL_FreeSurface(img);

    SDL_Event event;
    while (1) {
        while (SDL_PollEvent(&event)) {
            switch (event.type) {
            case SDL_QUIT:
                return 0;
            }
        }
    SDL_RenderClear(render);
    SDL_RenderCopy(render, texture, NULL, NULL);
    SDL_RenderPresent(render);
    }

    system("PAUSE");
    return 0;
}