「SDL第三篇」绘制基本图形

- points: 点数组。
- count: 点的个数。画线
int SDL_RenderDrawLine(SDL_Renderer* renderer,                      int           x1,                      int           y1,                      int           x2,                      int           y2)

- rects: 指定的矩形数组。
- count: 指定矩形个数。

SDL_SetRenderDrawColor(renderer, 0, 0, 255, 255);

#include "SDL.h"
#include <stdio.h>

#define POINTS_COUNT 4

static SDL_Point points[POINTS_COUNT] = {
    {320, 200},
    {300, 240},
    {340, 240},
    {320, 200}
};

static SDL_Rect bigrect = {0,0,540, 380};

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

    int flag = 1;

    SDL_Window *window;                    // Declare a pointer
    SDL_Renderer *renderer;

    SDL_Init(SDL_INIT_VIDEO);              // Initialize SDL2

    // Create an application window with the following settings:
    window = SDL_CreateWindow(
        "An SDL2 window",                  // window title
        SDL_WINDOWPOS_UNDEFINED,           // initial x position
        SDL_WINDOWPOS_UNDEFINED,           // initial y position
        640,                               // width, in pixels
        480,                               // height, in pixels
        SDL_WINDOW_SHOWN | SDL_WINDOW_BORDERLESS// flags - see below
    );

    // Check that the window was successfully created
    if (window == NULL) {
        // In the case that the window could not be made...
        printf("Could not create window: %s\n", SDL_GetError());
        return 1;
    }
    
    /* We must call SDL_CreateRenderer in order for draw calls to affect this window. */
    renderer = SDL_CreateRenderer(window, -1, 0);

    /* Select the color for drawing. It is set to red here. */
    SDL_SetRenderDrawColor(renderer, 255, 0, 0, 255);

    /* Clear the entire screen to our selected color. */
    SDL_RenderClear(renderer);

    SDL_SetRenderDrawColor(renderer, 255, 255, 255, SDL_ALPHA_OPAQUE);
    //SDL_RenderDrawLine(renderer, 100, 20, 500, 400);
    SDL_RenderDrawLines(renderer, points, POINTS_COUNT);

    SDL_Rect rect = {200, 300, 100, 100};
    SDL_RenderDrawRect(renderer, &rect);

    SDL_SetRenderDrawColor(renderer, 0, 255, 255, 255);
    SDL_RenderFillRect(renderer, &rect);

    SDL_SetRenderDrawColor(renderer, 0, 0, 255, 255);
    SDL_RenderFillRect(renderer, &bigrect);

    /* Up until now everything was drawn behind the scenes.
       This will show the new, red contents of the window. */
    SDL_RenderPresent(renderer);

    // The window is open: could enter program loop here (see SDL_PollEvent())

    SDL_Delay(3000);  // Pause execution for 3000 milliseconds, for example

    //destory renderer
    if (renderer) {
        SDL_DestroyRenderer(renderer);
    }

    // Close and destroy the window
    SDL_DestroyWindow(window);

    // Clean up
    SDL_Quit();
    return 0;
}