使用 SDL_Rect 创建多个矩形

Question

我正在使用 C 和 SDL 创建康威生命游戏的模拟。为了表示事件的细胞，我想在我创建的窗口中创建多个矩形。有没有办法在 for 循环中调用 SDL_Rect 而无需重新定义 SDL_Rect 并在同一个渲染器上输出 for 循环的结果？谢谢。

我的代码:

#include <stdio.h>
#include <math.h>
#include <stdlib.h>
#include <time.h>
#include <stdbool.h>
#include <SDL.h>
#define main SDL_main
#undef main

double CreateRectanglesX()
{   
    double x; double x_max = 640; double x_min = 20;
    x = rand() / (x_max - x_min) / (double)RAND_MAX + x_min;
    return x;
}

double CreateRectanglesY()
{
    double y; double y_max = 480; double y_min = 20; 
    y = rand() / (y_max - y_min) / (double)RAND_MAX + y_min;
    return y; 
}

int main(int argc, char* argv[])
{
    SDL_Init(SDL_INIT_VIDEO); //initializes the SDL/SDL2 window

    SDL_Window *screen; //SDL window created with pointer 
    screen = SDL_CreateWindow("My Program Window", SDL_WINDOWPOS_UNDEFINED, SDL_WINDOWPOS_UNDEFINED, 640, 480, SDL_WINDOW_OPENGL); 
    //definition for pointer - dimensions of SDL window

    SDL_Renderer *renderer; //Renderer created with pointer
    renderer = SDL_CreateRenderer(screen, -1, SDL_RENDERER_ACCELERATED); //definition for pointer - still to learn

    if (screen == NULL) //checks if window exists or not
    {
        printf("Could not create window: %s\n", SDL_GetError()); //returns error if window doesn't exsit
        return 1;
    } 

    SDL_SetRenderDrawColor(renderer, 0, 0, 0, 255); //changes color of renderer
    SDL_RenderClear(renderer); 
    SDL_RenderPresent(renderer); //displays the renderer with the changed color

    for (int i = 0; i < 5; i++)
    {
        double x = CreateRectanglesX();
        double y = CreateRectanglesY();
        printf("%lf %lf", x, y);
        SDL_Rect a;
        a.x = x;
        a.y = y;
        a.w = 20;
        a.h = 20;
        SDL_SetRenderDrawColor(renderer, 0, 0, 255, 255);
        SDL_RenderFillRect(renderer, &a);
        SDL_RenderPresent(renderer);
    }

    SDL_Delay(5000); //wait time for window
    SDL_DestroyWindow(screen);
    SDL_QUIT;

    return EXIT_SUCCESS;
}

Answer 1

错误在于我使用 CreateRectanglesX() 和 CreateRectanglesY 的随机数生成公式是错误的。这是

v = rand() / (x_max - x_min) / RAND_MAX + x_min;

应该是:

v = rand() * (x_max - x_min) / RAND_MAX + x_min; 

仅显示一个矩形，因为随机生成函数生成的随机数太接近(由于公式错误)。修改公式解决了问题!