关于SDL构建ios记录

构建ios版SDL相关资料：
https://stackoverflow.com/questions/64207191/build-sdl-sources-for-ios-developement-with-xcode-12
https://blog.wasin.io/2018/10/19/build-sdl2-application-on-ios.html
https://blog.aclysma.com/rust-on-ios-with-sdl2/
https://jstookey.com/building-sdl2-projects-for-ios-with-xcode-11/

UIWindow切换相关资料
https://www.codenong.com/51105924/

分享文件并拷贝到doc目录
https://blog.csdn.net/zhangshichi/article/details/81392504

压缩解压zip文件
https://github.com/ZipArchive/ZipArchive

SDL绘制椭圆

//draw one quadrant arc, and mirror the other 4 quadrants
void sdl_ellipse(SDL_Renderer* r, int x0, int y0, int radiusX, int radiusY)
{
    float pi  = 3.14159265358979323846264338327950288419716939937510;
    float pih = pi / 2.0; //half of pi

    //drew  28 lines with   4x4  circle with precision of 150 0ms
    //drew 132 lines with  25x14 circle with precision of 150 0ms
    //drew 152 lines with 100x50 circle with precision of 150 3ms
    const int prec = 27; // precision value; value of 1 will draw a diamond, 27 makes pretty smooth circles.
    float theta = 0;     // angle that will be increased each loop

    //starting point
    int x  = (float)radiusX * cos(theta);//start point
    int y  = (float)radiusY * sin(theta);//start point
    int x1 = x;
    int y1 = y;

    //repeat until theta >= 90;
    float step = pih/(float)prec; // amount to add to theta each time (degrees)
    for(theta=step;  theta <= pih;  theta+=step)//step through only a 90 arc (1 quadrant)
    {
        //get new point location
        x1 = (float)radiusX * cosf(theta) + 0.5; //new point (+.5 is a quick rounding method)
        y1 = (float)radiusY * sinf(theta) + 0.5; //new point (+.5 is a quick rounding method)

        //draw line from previous point to new point, ONLY if point incremented
        if( (x != x1) || (y != y1) )//only draw if coordinate changed
        {
            SDL_RenderDrawLine(r, x0 + x, y0 - y,    x0 + x1, y0 - y1 );//quadrant TR
            SDL_RenderDrawLine(r, x0 - x, y0 - y,    x0 - x1, y0 - y1 );//quadrant TL
            SDL_RenderDrawLine(r, x0 - x, y0 + y,    x0 - x1, y0 + y1 );//quadrant BL
            SDL_RenderDrawLine(r, x0 + x, y0 + y,    x0 + x1, y0 + y1 );//quadrant BR
        }
        //save previous points
        x = x1;//save new previous point
        y = y1;//save new previous point
    }
    //arc did not finish because of rounding, so finish the arc
    if(x!=0)
    {
        x=0;
        SDL_RenderDrawLine(r, x0 + x, y0 - y,    x0 + x1, y0 - y1 );//quadrant TR
        SDL_RenderDrawLine(r, x0 - x, y0 - y,    x0 - x1, y0 - y1 );//quadrant TL
        SDL_RenderDrawLine(r, x0 - x, y0 + y,    x0 - x1, y0 + y1 );//quadrant BL
        SDL_RenderDrawLine(r, x0 + x, y0 + y,    x0 + x1, y0 + y1 );//quadrant BR
    }
}

SDL_gfx:
http://www.ferzkopp.net/wordpress/2016/01/02/sdl_gfx-sdl2_gfx/