SDL Linux下的使用 计算机图形学

 

使用它来画一条直线

Ultility.h

#ifndef ULTILITY_H_INCLUDED#define ULTILITY_H_INCLUDED#ifdef __APPLE__#include <SDL/SDL.h>#else#include <SDL.h>#endif//init the screenint init(SDL_Surface *&screen,SDL_Surface *&pic,int w,int h);//draw a pixelvoid DrawPixel(SDL_Surface *screen, int x,int y,Uint8 R, Uint8 G, Uint8 B);//show a pic and free the resourcevoid Load(SDL_Surface *screen,SDL_Surface *pic);#endif // DRAWPIXEL_H_INCLUDED 

 

Example.h

#ifndef EXAMPLE_H_INCLUDED#define EXAMPLE_H_INCLUDED#ifdef __APPLE__#include <SDL/SDL.h>#else#include <SDL.h>#endif//Linevoid DDA_Line(int x0,int y0,int x1,int y1,SDL_Surface *pic);void MidPoint_Line(int x0,int y0,int x1,int y1,SDL_Surface *pic);//end Line#endif // EXAMPLE_H_INCLUDED 

 

Ultility.cpp

#include "Ultility.h"//init the screenint init(SDL_Surface *&screen,SDL_Surface *&pic,int w,int h){// initialize SDL video if ( SDL_Init( SDL_INIT_VIDEO ) < 0 ) { printf( "Unable to init SDL: %s/n", SDL_GetError() ); return 1; } // make sure SDL cleans up before exit atexit(SDL_Quit); // create a new window screen = SDL_SetVideoMode(w, h, 32,SDL_HWSURFACE|SDL_DOUBLEBUF); pic = SDL_CreateRGBSurface(SDL_SWSURFACE,w,h,32, 0, 0,0,0);}//draw a pixelvoid DrawPixel(SDL_Surface *screen, int x,int y,Uint8 R, Uint8 G, Uint8 B){ Uint32 color = SDL_MapRGB(screen->format, R, G, B); if ( SDL_MUSTLOCK(screen) ) { if ( SDL_LockSurface(screen) < 0 ) { return; } } switch (screen->format->BytesPerPixel) { case 1: { /* 假定是8-bpp */ Uint8 *bufp; bufp = (Uint8 *)screen->pixels + y*screen->pitch + x; *bufp = color; } break; case 2: { /* 可能是15-bpp 或者 16-bpp */ Uint16 *bufp; bufp = (Uint16 *)screen->pixels + y*screen->pitch/2 + x; *bufp = color; } break; case 3: { /* 慢速的24-bpp模式，通常不用 */ Uint8 *bufp; bufp = (Uint8 *)screen->pixels + y*screen->pitch + x; *(bufp+screen->format->Rshift/8) = R; *(bufp+screen->format->Gshift/8) = G; *(bufp+screen->format->Bshift/8) = B; } break; case 4: { /* 可能是32-bpp */ Uint32 *bufp; bufp = (Uint32 *)screen->pixels + y*screen->pitch/4 + x; *bufp = color; } break; } if ( SDL_MUSTLOCK(screen) ) { SDL_UnlockSurface(screen); } SDL_UpdateRect(screen, x, y, 1, 1);}void Load(SDL_Surface *screen,SDL_Surface *pic){ // centre the bitmap on screen SDL_Rect dstrect; dstrect.x = (screen->w - pic->w) / 2; dstrect.y = (screen->h - pic->h) / 2;// DRAWING STARTS HERE// clear screenSDL_FillRect(screen, 0, SDL_MapRGB(screen->format, 0, 0, 0));// draw bitmapSDL_BlitSurface(pic, 0, screen, &dstrect);// DRAWING ENDS HERE// finally, update the screen :)SDL_Flip(screen); // free loaded bitmap SDL_FreeSurface(pic); // all is well ;)} 

 

Line.cpp

#include "Ultility.h"//init the screenint init(SDL_Surface *&screen,SDL_Surface *&pic,int w,int h){// initialize SDL video if ( SDL_Init( SDL_INIT_VIDEO ) < 0 ) { printf( "Unable to init SDL: %s/n", SDL_GetError() ); return 1; } // make sure SDL cleans up before exit atexit(SDL_Quit); // create a new window screen = SDL_SetVideoMode(w, h, 32,SDL_HWSURFACE|SDL_DOUBLEBUF); pic = SDL_CreateRGBSurface(SDL_SWSURFACE,w,h,32, 0, 0,0,0);}//draw a pixelvoid DrawPixel(SDL_Surface *screen, int x,int y,Uint8 R, Uint8 G, Uint8 B){ Uint32 color = SDL_MapRGB(screen->format, R, G, B); if ( SDL_MUSTLOCK(screen) ) { if ( SDL_LockSurface(screen) < 0 ) { return; } } switch (screen->format->BytesPerPixel) { case 1: { /* 假定是8-bpp */ Uint8 *bufp; bufp = (Uint8 *)screen->pixels + y*screen->pitch + x; *bufp = color; } break; case 2: { /* 可能是15-bpp 或者 16-bpp */ Uint16 *bufp; bufp = (Uint16 *)screen->pixels + y*screen->pitch/2 + x; *bufp = color; } break; case 3: { /* 慢速的24-bpp模式，通常不用 */ Uint8 *bufp; bufp = (Uint8 *)screen->pixels + y*screen->pitch + x; *(bufp+screen->format->Rshift/8) = R; *(bufp+screen->format->Gshift/8) = G; *(bufp+screen->format->Bshift/8) = B; } break; case 4: { /* 可能是32-bpp */ Uint32 *bufp; bufp = (Uint32 *)screen->pixels + y*screen->pitch/4 + x; *bufp = color; } break; } if ( SDL_MUSTLOCK(screen) ) { SDL_UnlockSurface(screen); } SDL_UpdateRect(screen, x, y, 1, 1);}void Load(SDL_Surface *screen,SDL_Surface *pic){ // centre the bitmap on screen SDL_Rect dstrect; dstrect.x = (screen->w - pic->w) / 2; dstrect.y = (screen->h - pic->h) / 2;// DRAWING STARTS HERE// clear screenSDL_FillRect(screen, 0, SDL_MapRGB(screen->format, 0, 0, 0));// draw bitmapSDL_BlitSurface(pic, 0, screen, &dstrect);// DRAWING ENDS HERE// finally, update the screen :)SDL_Flip(screen); // free loaded bitmap SDL_FreeSurface(pic); // all is well ;)} 

 

main.cpp

#ifdef __cplusplus #include <cstdlib>#else #include <stdlib.h>#endif#include "Ultility.h"#include "Example.h"int main ( int argc, char** argv ){ // create a new window SDL_Surface* screen; SDL_Surface* pic; init(screen,pic,640,480); MidPoint_Line(0,0,100,100,pic); Load(screen,pic); getchar(); printf("Exited cleanly/n"); return 0;}