上面就是一个精灵图，由多个固定间隔的图标组成。利用精灵图的好处就是不必将图标逐个读入内存进行操作。我们可以将精灵图中需要的部分用一个个矩形截取下来，然后再输出到渲染器上。
环境：SDL2 + VC++2015
下面的代码将打开sprite.png，并对相应的操作做出响应。
sprite.png
1 #include2 #include 3 #include 4 #include "SDL.h" 5 #include "SDL_image.h" 6 7 //屏幕宽度 8 const int SCREEN_WIDTH = 500; 9 const int SCREEN_HEIGHT = 500; 10 11 //全局窗口和渲染器 12 SDL_Window *window = nullptr; 13 SDL_Renderer *renderer = nullptr; 14 15 //记录SDL错误 16 void logSDLError(std::ostream &os, const std::string &msg) 17 { 18 os << msg << " error: " << SDL_GetError() << std::endl; 19 } 20 21 //加载图像材质 22 SDL_Texture* loadTexture(const std::string &file, SDL_Renderer *ren) 23 { 24 SDL_Texture *texture = IMG_LoadTexture(ren, file.c_str()); 25 if (texture == nullptr) logSDLError(std::cout, "LoadTexture"); 26 return texture; 27 } 28 29 30 //根据坐标生成截取区域并复制输出到渲染器 31 void renderTexture(SDL_Texture *tex, SDL_Renderer *ren, int x, int y, SDL_Rect *clip = nullptr) 32 { 33 //目标截面区域初始化，提供目标在渲染器的坐标 34 SDL_Rect dst; dst.x = x; dst.y = y; 35 //源截面区域不为空，将其值赋给目标截面 36 if (clip != nullptr) { dst.w = clip->w; dst.h = clip->h; } 37 //将截面输出到渲染器 38 SDL_RenderCopy(ren, tex, clip, &dst); 39 } 40 41 int main(int argc, char** argv) 42 { 43 //初始化SDL 44 if (SDL_Init(SDL_INIT_EVERYTHING) == -1) 45 { 46 std::cout << SDL_GetError() << std::endl; 47 return 1; 48 } 49 50 //创建窗口 51 window = SDL_CreateWindow("Lesson 5", 52 SDL_WINDOWPOS_CENTERED, SDL_WINDOWPOS_CENTERED, 53 SCREEN_WIDTH, SCREEN_HEIGHT, SDL_WINDOW_SHOWN); 54 if (window == nullptr) 55 { 56 std::cout << SDL_GetError() << std::endl; 57 return 2; 58 } 59 60 //创建渲染器 61 renderer = SDL_CreateRenderer(window, -1, SDL_RENDERER_ACCELERATED | SDL_RENDERER_PRESENTVSYNC); 62 if (renderer == nullptr) 63 { 64 std::cout << SDL_GetError() << std::endl; 65 return 3; 66 } 67 68 //创建纹理 69 SDL_Texture *image = nullptr; 70 try 71 { 72 image = loadTexture("sprite.png", renderer); 73 } 74 catch (const std::runtime_error &e) 75 { 76 std::cout << e.what() << std::endl; 77 return 4; 78 } 79 80 //iW，iH 表示截面宽高 81 int iW = 100, iH = 100; 82 //x，y 分别为截面在渲染器输出的坐标 83 int x = SCREEN_WIDTH / 2 - iW / 2; 84 int y = SCREEN_HEIGHT / 2 - iH / 2; 85 86 //为精灵图设置截面 87 SDL_Rect clips[4]; 88 89 //初始化截面信息 90 for (int i = 0; i < 4; ++i) 91 { 92 clips[i].x = i / 2 * iW; 93 clips[i].y = i % 2 * iH; 94 clips[i].w = iW; 95 clips[i].h = iH; 96 } 97 98 //表示将要输出的截面 99 int useClip = 0;100 101 SDL_Event e;102 bool quit = false;103 //主循环104 while (!quit)105 {106 //事件轮询107 while (SDL_PollEvent(&e))108 {109 //按右上角的X退出110 if (e.type == SDL_QUIT) quit = true;111 112 //点击鼠标随机输出截面113 if (e.type == SDL_MOUSEBUTTONDOWN) useClip = rand() % 4;114 115 //使用数字键决定输出截面，分别有1，2，3，4116 if (e.type == SDL_KEYDOWN)117 {118 switch (e.key.keysym.sym)119 {120 case SDLK_1:121 case SDLK_KP_1:122 useClip = 0;123 break;124 case SDLK_2:125 case SDLK_KP_2:126 useClip = 1;127 break;128 case SDLK_3:129 case SDLK_KP_3:130 useClip = 2;131 break;132 case SDLK_4:133 case SDLK_KP_4:134 useClip = 3;135 break;136 case SDLK_ESCAPE:137 quit = true;138 break;139 default:140 break;141 }142 }143 }144 //清空渲染器145 SDL_RenderClear(renderer);146 //绘制材质147 renderTexture(image, renderer, x, y, &clips[useClip]);148 //呈现渲染器149 SDL_RenderPresent(renderer);150 }151 152 //释放资源153 SDL_DestroyTexture(image);154 SDL_DestroyRenderer(renderer);155 SDL_DestroyWindow(window);156 157 SDL_Quit();158 159 return 0;160 }