test/testdyngl.c

   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 */