SDL系列之 - 用画直线的方法来画正弦曲线

 1 #include <SDL.h>
 2 #include <stdlib.h>
 3 #include <string.h>
 4 #include <math.h>
 5 #include "SDL_draw.h"           //包含SDL_draw库的头文件
 6 int main()
 7 {
 8         int i;
 9         double t;
10         double x,y;
11         double x0=320, y0=240;
12         Uint32 screen_color;
13         SDL_Surface *screen;    //一个屏幕指针
14         if(SDL_Init(SDL_INIT_VIDEO) < 0){       //初始化视频子系统失败
15                 fprintf(stderr,"无法初始化:%s\n",SDL_GetError());       //不能用printf()，因为没有包含stdio.h头文件
16                 exit(1);
17         }           
18         //设置视频模式
19         screen=SDL_SetVideoMode(640,480,16,SDL_SWSURFACE);
20         if(screen==NULL){
21                 fprintf(stderr,"无法设置视频模式:%s\n",SDL_GetError());
22                 exit(1);
23         }   
24         atexit(SDL_Quit);       //退出
25 
26         //画直线，从点(240,180)到点(400,300),颜色为白色
27         Draw_Line(screen,240,180,400,300,SDL_MapRGB(screen->format, 255,255,255));
28         //画直线，从点(400,180)到点(240,300),颜色为蓝色
29         Draw_Line(screen,400,180,240,300,SDL_MapRGB(screen->format, 0,0,255));
30         for(i=0;i<640;i+=2){
31                 x=240-120*sin(3.14*i/180);
32                 i+=2;
33                 y=240-120*sin(3.14*i/180);
34                 Draw_Line(screen,i-2,x,i,y,SDL_MapRGB(screen->format, 0,0,255));
35                 SDL_Delay(5);                   //停留5毫秒
36                 SDL_UpdateRect(screen,0,0,0,0);         //更新整个屏幕
37         }       
38         SDL_UpdateRect(screen,0,0,0,0);         //更新整个屏幕
39         SDL_Delay(3000);                        //停留5秒
40         return 0;
41 }