sdl笔记

sdl教程教程
https://github.com/Twinklebear/TwinklebearDev-Lessons

asm.js的教程
https://github.com/3dgen/cppwasm-book
入门
http://www.ruanyifeng.com/blog/2017/09/asmjs_emscripten.html



#######
vim格式化：
1，gg 跳转到第一行
2，shift+v 转到可视模式
3，shift+g 全选
4，按下神奇的 =


centos7安装

yum install SDL SDL-devel SDL-static -y
helloworld
https://www.linuxidc.com/Linux/2012-12/75255.htm

main.c

#include "SDL/SDL.h"  
int main( int argc, char* args[] )  
{  
    //Start SDL  
    SDL_Init( SDL_INIT_EVERYTHING );  
    //Quit SDL  
    SDL_Quit();  
    return 0;      
} 

加载一张图片
在mac下的例子参考
https://github.com/killinux/ffmpeg-leaning/tree/master/sdl/sdl_practic_1
或者我的mtcode

#include <iostream>
extern "C" {
#include <SDL2/SDL.h>
#include <SDL2/SDL_test_images.h>
}
using namespace  std;

const int WIDTH = 960, HEIGHT = 540;
int main() {

    SDL_Surface *imageSurface = NULL;
    SDL_Surface *windowSurface = NULL;

    if (SDL_Init(SDL_INIT_EVERYTHING) < 0) {
        cout << "SDL could not initialized with error: " << SDL_GetError() << endl;
    }
    SDL_Window *window = SDL_CreateWindow("Hello SDL world!", SDL_WINDOWPOS_CENTERED, SDL_WINDOWPOS_CENTERED,
                                          WIDTH, HEIGHT, SDL_WINDOW_ALLOW_HIGHDPI);
    if (NULL == window) {
        cout << "SDL could not create window with error: " << SDL_GetError() << endl;
    }

    windowSurface = SDL_GetWindowSurface(window);
    imageSurface = SDL_LoadBMP("little_prince.bmp");
    if (NULL == imageSurface) {
        cout << "SDL could not load image with error: " << SDL_GetError() << endl;
    }
    SDL_Event windowEvent;
    while(true) {
        if (SDL_PollEvent(&windowEvent)) {
            if (SDL_QUIT == windowEvent.type) {
                cout << "SDL quit!!" << endl;
                break;
            }
        }

        SDL_BlitSurface(imageSurface, NULL, windowSurface, NULL);
        SDL_UpdateWindowSurface(window);
    }

    imageSurface = NULL;
    windowSurface = NULL;
    SDL_DestroyWindow(window);
    SDL_Quit();
    return 0;
}

emscripten 加载文件
https://github.com/3dgen/cppwasm-book/blob/master/zh/ch3-runtime/ch3-03-fs.md






############################


emcc使用sdl2
emcc main.c -s USE_SDL=2 -o main.html

[url]https://www.jamesfmackenzie.com/2019/12/01/webassembly-graphics-with-sdl/
[/url]

https://blog.csdn.net/pkx1993/article/details/82015659?utm_source=blogxgwz4

Emscripten Ports

有用库的收集，并移植到Emscripten。Github地址：https://github.com/emscripten-ports

他们已经被整合到了emcc中。当你请求一个ports被使用时，emcc会从远程服务器获取，设置并在本地构建它，然后将其链接到您的项目，向您的构建命令添加必需的包含。
例如：SDL2是一个ports，可以请求并并使用命令-s USE_SDL=2链接他。

emcc tests/sdl2glshader.c -s USE_SDL=2 -s LEGACY_GL_EMULATION=1 -o sdl2.html

###############
SDL入门教程：
https://segmentfault.com/a/1190000011328496

emscripten 加载sdl的helloworld
hello_world_cube.cpp

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

#ifdef __EMSCRIPTEN__
#include <emscripten.h>
#endif

extern "C" int main(int argc, char** argv) {
  printf("hello, world!\n");

  SDL_Init(SDL_INIT_VIDEO);
  SDL_Surface *screen = SDL_SetVideoMode(256, 256, 32, SDL_SWSURFACE);

#ifdef TEST_SDL_LOCK_OPTS
  EM_ASM("SDL.defaults.copyOnLock = false; SDL.defaults.discardOnLock = true; SDL.defaults.opaqueFrontBuffer = false;");
#endif

  if (SDL_MUSTLOCK(screen)) SDL_LockSurface(screen);
  for (int i = 0; i < 256; i++) {
    for (int j = 0; j < 256; j++) {
#ifdef TEST_SDL_LOCK_OPTS
      // Alpha behaves like in the browser, so write proper opaque pixels.
      int alpha = 255;
#else
     // To emulate native behavior with blitting to screen, alpha component is ignored. Test that it is so by outputting
      // data (and testing that it does get discarded)
      int alpha = (i+j) % 255;
#endif
      *((Uint32*)screen->pixels + i * 256 + j) = SDL_MapRGBA(screen->format, i, j, 255-i, alpha);
    }
  }
  if (SDL_MUSTLOCK(screen)) SDL_UnlockSurface(screen);
  SDL_Flip(screen);

  printf("you should see a smoothly-colored square - no sharp lines but the square borders!\n");
  printf("and here is some text that should be HTML-friendly: amp: |&| double-quote: |\"| quote: |'| less-than, greater-than, html-like tags: |<cheez></cheez>|\nanother line.\n");

  SDL_Quit();

  return 0;
}

########
问题:
1.浏览器最基本的sdl
2.加载图片？