1 /* 2 * Small SDL example to demonstrate dynamically loading 3 * OpenGL lib and functions 4 * 5 * (FYI it was supposed to look like snow in the wind or something...) 6 * 7 * Compile with : 8 * gcc testdyngl.c `sdl-config --libs --cflags` -o testdyngl -DHAVE_OPENGL 9 * 10 * You can specify a different OpenGL lib on the command line, i.e. : 11 * ./testdyngl /usr/X11R6/lib/libGL.so.1.2 12 * or 13 * ./testdyngl /usr/lib/libGL.so.1.0.4496 14 * 15 */ 16 17 #include <stdio.h> 18 #include <stdlib.h> 19 20 #include "SDL.h" 21 22 #ifdef __MACOS__ 23 #define HAVE_OPENGL 24 #endif 25 26 #ifdef HAVE_OPENGL 27 28 #include "SDL_opengl.h" 29 30 /* Call this instead of exit(), so we can clean up SDL: atexit() is evil. */ 31 static void quit(int rc) 32 { 33 SDL_Quit(); 34 exit(rc); 35 } 36 37 void* get_funcaddr(const char* p) 38 { 39 void* f=SDL_GL_GetProcAddress(p); 40 if (f) 41 { 42 return f; 43 } 44 else 45 { 46 printf("Unable to get function pointer for %s\n",p); 47 quit(1); 48 } 49 return NULL; 50 } 51 52 typedef struct 53 { 54 void(APIENTRY*glBegin)(GLenum); 55 void(APIENTRY*glEnd)(); 56 void(APIENTRY*glVertex3f)(GLfloat, GLfloat, GLfloat); 57 void(APIENTRY*glClearColor)(GLfloat, GLfloat, GLfloat, GLfloat); 58 void(APIENTRY*glClear)(GLbitfield); 59 void(APIENTRY*glDisable)(GLenum); 60 void(APIENTRY*glEnable)(GLenum); 61 void(APIENTRY*glColor4ub)(GLubyte,GLubyte,GLubyte,GLubyte); 62 void(APIENTRY*glPointSize)(GLfloat); 63 void(APIENTRY*glHint)(GLenum,GLenum); 64 void(APIENTRY*glBlendFunc)(GLenum,GLenum); 65 void(APIENTRY*glMatrixMode)(GLenum); 66 void(APIENTRY*glLoadIdentity)(); 67 void(APIENTRY*glOrtho)(GLdouble,GLdouble,GLdouble,GLdouble,GLdouble,GLdouble); 68 void(APIENTRY*glRotatef)(GLfloat,GLfloat,GLfloat,GLfloat); 69 void(APIENTRY*glViewport)(GLint,GLint,GLsizei,GLsizei); 70 void(APIENTRY*glFogf)(GLenum,GLfloat); 71 } 72 glfuncs; 73 74 void init_glfuncs(glfuncs* f) 75 { 76 f->glBegin=get_funcaddr("glBegin"); 77 f->glEnd=get_funcaddr("glEnd"); 78 f->glVertex3f=get_funcaddr("glVertex3f"); 79 f->glClearColor=get_funcaddr("glClearColor"); 80 f->glClear=get_funcaddr("glClear"); 81 f->glDisable=get_funcaddr("glDisable"); 82 f->glEnable=get_funcaddr("glEnable"); 83 f->glColor4ub=get_funcaddr("glColor4ub"); 84 f->glPointSize=get_funcaddr("glPointSize"); 85 f->glHint=get_funcaddr("glHint"); 86 f->glBlendFunc=get_funcaddr("glBlendFunc"); 87 f->glMatrixMode=get_funcaddr("glMatrixMode"); 88 f->glLoadIdentity=get_funcaddr("glLoadIdentity"); 89 f->glOrtho=get_funcaddr("glOrtho"); 90 f->glRotatef=get_funcaddr("glRotatef"); 91 f->glViewport=get_funcaddr("glViewport"); 92 f->glFogf=get_funcaddr("glFogf"); 93 } 94 95 #define NB_PIXELS 1000 96 97 int main(int argc,char *argv[]) 98 { 99 glfuncs f; 100 int i; 101 SDL_Event event; 102 int done=0; 103 GLfloat pixels[NB_PIXELS*3]; 104 const char *gl_library = NULL; /* Use the default GL library */ 105 106 if (argv[1]) { 107 gl_library = argv[1]; 108 } 109 110 if (SDL_Init(SDL_INIT_VIDEO)<0) 111 { 112 printf("Unable to init SDL : %s\n",SDL_GetError()); 113 return(1); 114 } 115 116 if (SDL_GL_SetAttribute(SDL_GL_DOUBLEBUFFER,1)<0) 117 { 118 printf("Unable to set GL attribute : %s\n",SDL_GetError()); 119 quit(1); 120 } 121 122 if (SDL_GL_LoadLibrary(gl_library)<0) 123 { 124 printf("Unable to dynamically open GL lib : %s\n",SDL_GetError()); 125 quit(1); 126 } 127 128 if (SDL_SetVideoMode(640,480,0,SDL_OPENGL)==NULL) 129 { 130 printf("Unable to open video mode : %s\n",SDL_GetError()); 131 quit(1); 132 } 133 134 /* Set the window manager title bar */ 135 SDL_WM_SetCaption( "SDL Dynamic OpenGL Loading Test", "testdyngl" ); 136 137 init_glfuncs(&f); 138 139 for(i=0;i<NB_PIXELS;i++) 140 { 141 pixels[3*i]=rand()%250-125; 142 pixels[3*i+1]=rand()%250-125; 143 pixels[3*i+2]=rand()%250-125; 144 } 145 146 f.glViewport(0,0,640,480); 147 148 f.glMatrixMode(GL_PROJECTION); 149 f.glLoadIdentity(); 150 f.glOrtho(-100,100,-100,100,-500,500); 151 152 f.glMatrixMode(GL_MODELVIEW); 153 f.glLoadIdentity(); 154 155 f.glEnable(GL_DEPTH_TEST); 156 f.glDisable(GL_TEXTURE_2D); 157 f.glEnable(GL_BLEND); 158 f.glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA); 159 160 f.glClearColor(0.0f,0.0f,0.0f,0.0f); 161 f.glClear(GL_COLOR_BUFFER_BIT|GL_DEPTH_BUFFER_BIT); 162 163 f.glEnable(GL_POINT_SMOOTH); 164 f.glHint(GL_POINT_SMOOTH_HINT,GL_NICEST); 165 f.glPointSize(5.0f); 166 f.glEnable(GL_FOG); 167 f.glFogf(GL_FOG_START,-500); 168 f.glFogf(GL_FOG_END,500); 169 f.glFogf(GL_FOG_DENSITY,0.005); 170 171 do 172 { 173 f.glClear(GL_COLOR_BUFFER_BIT|GL_DEPTH_BUFFER_BIT); 174 175 f.glRotatef(2.0,1.0,1.0,1.0); 176 f.glRotatef(1.0,0.0,1.0,1.0); 177 178 f.glColor4ub(255,255,255,255); 179 f.glBegin(GL_POINTS); 180 for(i=0;i<NB_PIXELS;i++) 181 { 182 f.glVertex3f(pixels[3*i],pixels[3*i+1],pixels[3*i+2]); 183 } 184 f.glEnd(); 185 SDL_GL_SwapBuffers(); 186 187 while(SDL_PollEvent(&event)) 188 { 189 if(event.type & SDL_KEYDOWN) 190 done=1; 191 } 192 193 SDL_Delay(20); 194 } 195 while(!done); 196 197 SDL_Quit(); 198 return 0; 199 } 200 201 #else /* HAVE_OPENGL */ 202 203 int main(int argc, char *argv[]) 204 { 205 printf("No OpenGL support on this system\n"); 206 return 1; 207 } 208 209 #endif /* HAVE_OPENGL */ 210
