/*---------------------------------------------------------- main() ----------------------------------------------------------*/ int main(int argc, char* argv[]) { SDL_Surface *screen; GAMESTATE *gs; int i; int bpp = 0; int last_tick, start_time, end_time; int dashframe; float logic_fps = 20.0; int flags = SDL_DOUBLEBUF | SDL_HWSURFACE;
// SDL视频初始化
SDL_Init(SDL_INIT_VIDEO);
// 将函数SDL_Quit压入退出处理程序
atexit(SDL_Quit);
// 设置中断句柄,设置在Ctrl+Break和程序中止的时候,调用breakhandler
// 在breakhandler中重新设置了中断处理句柄,并将中断标志设为1
signal(SIGTERM, breakhandler); signal(SIGINT, breakhandler);
// 处理参数
for(i = 1; i < argc; ++i) { if(strncmp(argv[i], "-s", 2) == 0) flags &= ~SDL_DOUBLEBUF; else if(strncmp(argv[i], "-f", 2) == 0) flags |= SDL_FULLSCREEN; else bpp = atoi(&argv[i][1]); }
// 设置Video Mode的宽度和高度,由于bpp=0,所以使用当前的颜色数
screen = SDL_SetVideoMode(SCREEN_W, SCREEN_H, bpp, flags); if(!screen) { fprintf(stderr, "Failed to open screen!\n"); return 1; }
// 设置窗口的标题和ICON的名称
SDL_WM_SetCaption("Fixed Rate Pig", "Pig");
// 隐藏鼠标
SDL_ShowCursor(0);
// 初始化游戏状态结构
gs = init_all(screen); if(!gs) return 1;
// 取得键盘状态,键盘状态是一个Uint8的数组,包含所有按键的当前状态
// 使用例子if ( gs->keys[SDLK_RETURN] ) ... is pressed.
gs->keys = SDL_GetKeyState(&i);
// 初始化逻辑桢的相关信息
gs->logic_frames = 0; gs->rendered_frames = 0; gs->pe->before_objects = before_objects;
// 初始化Pig engine中的精灵和原图片
pig_start(gs->pe, 0); gs->***_screen = gs->pe->pages;
// 记录当前的时间
start_time = last_tick = SDL_GetTicks();
// 开始消息处理循环
while(gs->running) { int tick; float frames, dt; SDL_Event ev;
/* Handle input */ // SDL_PollEvent有点类似PeekMessage
while(SDL_PollEvent(&ev) > 0) // 处理键盘和鼠标事件
handle_input(gs, &ev);
// 空函数
handle_keys(gs);
// 判断程序是否被中断
// 前面通过signal设置当Ctrl+Break或者程序结束的中断发生时,break_received要设置为1
// 注意这里并没有直接中断消息循环,所以在处理完本次循环的操作以后才能真正退出
if(break_received) gs->running = 0;
/* Calculate time since last update */ // 这里用来计算和上次消息循环间隔的时间,并通过显示桢数参数来确定需要显示的逻辑桢的ID
tick = SDL_GetTicks(); dt = (tick - last_tick) * 0.001; frames = dt * logic_fps;
/* Run the game logic */ // 显示逻辑桢
pig_animate(gs->pe, frames);
/* * Limit the dashboard frame rate to 15 fps * when there's no wobbling going on. * * The 'dashframe' deal is about keeping the * pages in sync on a double buffered display. */ if(gs->lives_wobble || gs->score_wobble || (gs->dashboard_time > 1.0/15.0)) { dashframe = gs->pe->pages; gs->dashboard_time = 0; } if(dashframe) { --dashframe; dashboard(gs); }
/* Update sprites */ if(gs->***_screen) { --gs->***_screen; pig_***_all(gs->pe); } else pig_***(gs->pe);
/* Make the new frame visible */ pig_flip(gs->pe);
/* Update statistics, timers and stuff */ ++gs->rendered_frames; gs->lives_wobble_time += dt; gs->score_wobble_time += dt; gs->dashboard_time += dt;
// 记录时间方便最后的计算
last_tick = tick;
// nice似乎是某种效果的标志,目前还不确定
if(gs->nice) SDL_Delay(10); }
/* Print some statistics */ end_time = SDL_GetTicks(); i = end_time - start_time; printf(" Total time running: %d ms\n", i); if(!i) i = 1; printf("Average rendering frame rate: %.2f fps\n", gs->rendered_frames * 1000.0 / i); printf(" Average logic frame rate: %.2f fps\n", gs->logic_frames * 1000.0 / i);
// 释放Pig engine
pig_close(gs->pe); return 0; }
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