SDL Game Development-第1章-笔记

【简介】学习在Code::Blocks 13.12中，使用SDL2.0库的方法。基于g++的C++11选项

原书下载地址：http://it-ebooks.info/book/2960/

SDL2.0官方地址：http://www.libsdl.org/

第一章：程序的基本架构

main.cpp的内容

#include "Game.h"

Game* g_game = 0;   //全局实例

//这里演示了基本框架结构
int main(int argc, char* argv[])
{
g_game = new Game();    //Game类对象实例
g_game->init("Charpter 1", 100, 100, 640, 480, 0);  //初始化
//标题：Charpter 1,
//x,y位置：100, 100
//窗口宽高：640, 480
//窗口标志：0
//标志建议使用：SDL_WINDOW_SHOWN | SDL_WINDOW_ALLOW_HIGHDPI | SDL_WINDOW_OPENGL

while(g_game->running())    //开始主循环
{
g_game->handleEvents(); //处理输入
g_game->update();   //计算时间和碰撞
g_game->render();   //渲染到屏幕
}
g_game->clean();    //清理资源，退出

return 0;
}

Game.h的内容

#ifndef __Game__
#define __Game__
#include <SDL.h>

class Game
{
public:
Game();
~Game();
bool init(const char* title, int xpos, int ypos, int width, int height, int flags);  //初始化
void render();
void update();
void handleEvents();
void clean();
bool running() { return m_bRunning; }   //返回运行状态
private:
SDL_Window* m_pWindow;  //窗口资源指针
SDL_Renderer* m_pRenderer;  //渲染器资源指针
bool m_bRunning;

};

#endif // __Game__

Game.cpp的内容

#include <iostream>
//注：对于在VS 2012 EXPRESS的IDE中使用std::cout，
//需要包含Windows.h，
//然后调用AllocConsole(); 和freopen("CON", "w", stdout);
//将上述内容添加到main.cpp中
#include "Game.h"
Game::Game()
{

}
Game::~Game()
{

}
bool Game::init(const char* title, int xpos, int ypos, int width, int height, int flags)
{
if(SDL_Init(SDL_INIT_EVERYTHING) == 0)  //SDL_Init成功。参数也可写为SDL_INIT_VIDEO | SDL_INIT_TIMER
{
std::cout << "SDL init success\n";
//调用SDL的创建窗口函数，返回窗口资源指针
m_pWindow = SDL_CreateWindow(title, xpos, ypos, width, height, flags);
if(m_pWindow !=0)   //窗口创建成功
{
std::cout << "window creation success\n";
//创建渲染器资源
m_pRenderer = SDL_CreateRenderer(m_pWindow, -1, 0);
if(m_pRenderer != 0)    //渲染器创建成功
{
std::cout << "renderer creation success\n";
//设置当前渲染色，rgba，红绿蓝透明四通道
SDL_SetRenderDrawColor(m_pRenderer, 0xFF, 0xFF, 0xFF, 0xFF);
}else {
std::cout << "renderer init fail\n";
return false;   //渲染器失败
}
}else {
std::cout << "window init fail\n";
return false; //窗口创建失败
}
}else{
std::cout << "SDL init fail\n";
return false; //SDL库初始失败
}

std::cout << "init success\n";
m_bRunning = true;  //所有初始都成功，可以开始主循环了
return true;
}

void Game::render()
{
SDL_RenderClear(m_pRenderer);   //清屏
//绘制对象
SDL_RenderPresent(m_pRenderer); //双缓冲翻转，新内容显示到屏幕上
}

void Game::update()
{

}

void Game::handleEvents()
{
SDL_Event event;    //这个变量放这里合适否？每次循环都会生成这个局部变量
if(SDL_PollEvent(&event))
{
switch(event.type)
{
case SDL_QUIT:
m_bRunning = false; //结束循环
break;

default:
break;
}
}   //事件处理在第4章详细介绍
}

void Game::clean()
{
std::cout << "cleaning game\n";
SDL_DestroyWindow(m_pWindow);   //销毁资源，可以加上判断
//if(m_pWindow) { SDL_DestroyWindow(m_pWindow); }
SDL_DestroyRenderer(m_pRenderer);
SDL_Quit();
}

运行结果：



最后：关于全屏

//修改Game.h中的init()函数原型

bool init(const char* title, int xpos, int ypos, int width, int height, bool fullscreen);

//修改Game.cpp中的init()函数实现

bool Game::init(const char* title, int xpos, int ypos, int width, int height, bool fullscreen)

{

flags = 0;

if(fullscreen)

flags = SDL_WINDOW_FULLSCREEN;

//上述代码放在SDL_CreateWindow()之前

...

//main.cpp中的调用代码，改为
if(g_game->init("Chapter 1", 100, 100, 640, 480, true));

//true传入，指示全屏创建窗口