test/testdyngl.c
author Patrice Mandin <patmandin@gmail.com>
Fri, 26 Nov 2004 16:13:24 +0000
changeset 990 8e20c48a9c13
parent 910 4ab6d1fd028f
child 1151 be9c9c8f6d53
permissions -rw-r--r--
Restore everything when a function pointer is NULL
     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 HAVE_OPENGL
    23 
    24 #include "SDL_opengl.h"
    25 
    26 void* get_funcaddr(const char* p)
    27 {
    28 	void* f=SDL_GL_GetProcAddress(p);
    29 	if (f)
    30 	{
    31 		return f;
    32 	}
    33 	else
    34 	{
    35 		printf("Unable to get function pointer for %s\n",p);
    36 		exit(1);
    37 	}
    38 }
    39 
    40 typedef struct
    41 {
    42 	void(APIENTRY*glBegin)(GLenum);
    43 	void(APIENTRY*glEnd)();
    44 	void(APIENTRY*glVertex3f)(GLfloat, GLfloat, GLfloat);
    45 	void(APIENTRY*glClearColor)(GLfloat, GLfloat, GLfloat, GLfloat);
    46 	void(APIENTRY*glClear)(GLbitfield);
    47 	void(APIENTRY*glDisable)(GLenum);
    48 	void(APIENTRY*glEnable)(GLenum);
    49 	void(APIENTRY*glColor4ub)(GLubyte,GLubyte,GLubyte,GLubyte);
    50 	void(APIENTRY*glPointSize)(GLfloat);
    51 	void(APIENTRY*glHint)(GLenum,GLenum);
    52 	void(APIENTRY*glBlendFunc)(GLenum,GLenum);
    53 	void(APIENTRY*glMatrixMode)(GLenum);
    54 	void(APIENTRY*glLoadIdentity)();
    55 	void(APIENTRY*glOrtho)(GLdouble,GLdouble,GLdouble,GLdouble,GLdouble,GLdouble);
    56 	void(APIENTRY*glRotatef)(GLfloat,GLfloat,GLfloat,GLfloat);
    57 	void(APIENTRY*glViewport)(GLint,GLint,GLsizei,GLsizei);
    58 	void(APIENTRY*glFogf)(GLenum,GLfloat);
    59 }
    60 glfuncs;
    61 
    62 void init_glfuncs(glfuncs* f)
    63 {
    64 	f->glBegin=get_funcaddr("glBegin");
    65 	f->glEnd=get_funcaddr("glEnd");
    66 	f->glVertex3f=get_funcaddr("glVertex3f");
    67 	f->glClearColor=get_funcaddr("glClearColor");
    68 	f->glClear=get_funcaddr("glClear");
    69 	f->glDisable=get_funcaddr("glDisable");
    70 	f->glEnable=get_funcaddr("glEnable");
    71 	f->glColor4ub=get_funcaddr("glColor4ub");
    72 	f->glPointSize=get_funcaddr("glPointSize");
    73 	f->glHint=get_funcaddr("glHint");
    74 	f->glBlendFunc=get_funcaddr("glBlendFunc");
    75 	f->glMatrixMode=get_funcaddr("glMatrixMode");
    76 	f->glLoadIdentity=get_funcaddr("glLoadIdentity");
    77 	f->glOrtho=get_funcaddr("glOrtho");
    78 	f->glRotatef=get_funcaddr("glRotatef");
    79 	f->glViewport=get_funcaddr("glViewport");
    80 	f->glFogf=get_funcaddr("glFogf");
    81 }
    82 
    83 #define NB_PIXELS 1000
    84 
    85 int main(int argc,char *argv[])
    86 {
    87 	glfuncs f;
    88 	int i;
    89 	SDL_Event event;
    90 	int done=0;
    91 	GLfloat pixels[NB_PIXELS*3];
    92 #if defined(_WIN32)
    93 	char *gl_library = "OpenGL32.DLL";
    94 #elif defined(__QNXNTO__)
    95 	char *gl_library = "libGL.so.3";
    96 #else
    97 	char *gl_library = "libGL.so.1";
    98 #endif
    99 	
   100 	if (argv[1]) {
   101 		gl_library = argv[1];
   102 	}
   103 	
   104 	if (SDL_Init(SDL_INIT_VIDEO)<0)
   105 	{
   106 		printf("Unable to init SDL : %s\n",SDL_GetError());
   107 		exit(1);
   108 	}
   109 
   110 	atexit(SDL_Quit);
   111 	
   112 	if (SDL_GL_SetAttribute(SDL_GL_DOUBLEBUFFER,1)<0)
   113 	{
   114 		printf("Unable to set GL attribute : %s\n",SDL_GetError());
   115 		exit(1);
   116 	}
   117 	
   118 	if (SDL_GL_LoadLibrary(gl_library)<0)
   119 	{
   120 		printf("Unable to dynamically open GL lib : %s\n",SDL_GetError());
   121 		exit(1);
   122 	}
   123 
   124 	if (SDL_SetVideoMode(640,480,0,SDL_OPENGL)==NULL)
   125 	{
   126 		printf("Unable to open video mode : %s\n",SDL_GetError());
   127 		exit(1);
   128 	}
   129 
   130 	/* Set the window manager title bar */
   131 	SDL_WM_SetCaption( "SDL Dynamic OpenGL Loading Test", "testdyngl" );
   132 
   133 	init_glfuncs(&f);
   134 
   135 	for(i=0;i<NB_PIXELS;i++)
   136 	{
   137 		pixels[3*i]=rand()%250-125;
   138 		pixels[3*i+1]=rand()%250-125;
   139 		pixels[3*i+2]=rand()%250-125;
   140 	}
   141 	
   142 	f.glViewport(0,0,640,480);
   143 	
   144 	f.glMatrixMode(GL_PROJECTION);
   145 	f.glLoadIdentity();
   146 	f.glOrtho(-100,100,-100,100,-500,500);
   147 	
   148 	f.glMatrixMode(GL_MODELVIEW);
   149 	f.glLoadIdentity();
   150 	
   151 	f.glEnable(GL_DEPTH_TEST);
   152 	f.glDisable(GL_TEXTURE_2D);
   153 	f.glEnable(GL_BLEND);
   154 	f.glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
   155 	
   156 	f.glClearColor(0.0f,0.0f,0.0f,0.0f);
   157 	f.glClear(GL_COLOR_BUFFER_BIT|GL_DEPTH_BUFFER_BIT);
   158 	
   159 	f.glEnable(GL_POINT_SMOOTH);
   160 	f.glHint(GL_POINT_SMOOTH_HINT,GL_NICEST);
   161 	f.glPointSize(5.0f);
   162 	f.glEnable(GL_FOG);
   163 	f.glFogf(GL_FOG_START,-500);
   164 	f.glFogf(GL_FOG_END,500);
   165 	f.glFogf(GL_FOG_DENSITY,0.005);
   166 	
   167 	do
   168 	{
   169 		f.glClear(GL_COLOR_BUFFER_BIT|GL_DEPTH_BUFFER_BIT);
   170 		
   171 		f.glRotatef(2.0,1.0,1.0,1.0);
   172 		f.glRotatef(1.0,0.0,1.0,1.0);
   173 		
   174 		f.glColor4ub(255,255,255,255);
   175 		f.glBegin(GL_POINTS);
   176 		for(i=0;i<NB_PIXELS;i++)
   177 		{
   178 			f.glVertex3f(pixels[3*i],pixels[3*i+1],pixels[3*i+2]);
   179 		}
   180 		f.glEnd();
   181 		SDL_GL_SwapBuffers();
   182 
   183 		while(SDL_PollEvent(&event))
   184 		{
   185 			if(event.type & SDL_KEYDOWN)
   186 				done=1;
   187 		}
   188 
   189 		SDL_Delay(20);
   190 	}
   191 	while(!done);
   192 	
   193 	SDL_Quit();
   194 	return 0;
   195 }
   196 
   197 #else /* HAVE_OPENGL */
   198 
   199 int main(int argc, char *argv[])
   200 {
   201 	printf("No OpenGL support on this system\n");
   202 	return 1;
   203 }
   204 
   205 #endif /* HAVE_OPENGL */