test/testdyngl.c
author Ryan C. Gordon <icculus@icculus.org>
Mon, 18 Feb 2019 00:26:53 -0500
changeset 69 a2c5f6a01a55
parent 0 a6cb692b8939
permissions -rw-r--r--
Fill in a default palette for 8-bit screen surfaces.
     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 */