test/testdyngl.c
author Sam Lantinga <slouken@libsdl.org>
Fri, 30 Apr 2004 18:33:30 +0000
changeset 885 9f6ad2286011
parent 847 0afe0e38e02c
child 910 4ab6d1fd028f
permissions -rw-r--r--
Date: Wed, 28 Apr 2004 16:52:41 -0400 From: "Damien A" Subject: testdyngl fix The test program you included in the latest version of SDL crashes on startup in Window (XP). The reason for this is that OpenGL functions on Windows use the __stdcall calling convention, not the C convention. Placing APIENTRY infront of the * operator solves this problem.

/*
 * Small SDL example to demonstrate dynamically loading 
 * OpenGL lib and functions
 *
 * (FYI it was supposed to look like snow in the wind or something...)
 *
 * Compile with :
 * gcc testdyngl.c `sdl-config --libs --cflags` -o testdyngl -DHAVE_OPENGL
 *
 * You can specify a different OpenGL lib on the command line, i.e. :
 * ./testdyngl  /usr/X11R6/lib/libGL.so.1.2
 * or
 * ./testdyngl  /usr/lib/libGL.so.1.0.4496
 *
 */

#include <stdio.h>
#include <stdlib.h>

#include "SDL.h"

#ifdef HAVE_OPENGL

#include "SDL_opengl.h"

void* get_funcaddr(const char* p)
{
	void* f=SDL_GL_GetProcAddress(p);
	if (f)
	{
		return f;
	}
	else
	{
		printf("Unable to get function pointer for %s\n",p);
		exit(1);
	}
}

typedef struct
{
	void(APIENTRY*glBegin)(GLenum);
	void(APIENTRY*glEnd)();
	void(APIENTRY*glVertex3f)(GLfloat, GLfloat, GLfloat);
	void(APIENTRY*glClearColor)(GLfloat, GLfloat, GLfloat, GLfloat);
	void(APIENTRY*glClear)(GLbitfield);
	void(APIENTRY*glDisable)(GLenum);
	void(APIENTRY*glEnable)(GLenum);
	void(APIENTRY*glColor4ub)(GLubyte,GLubyte,GLubyte,GLubyte);
	void(APIENTRY*glPointSize)(GLfloat);
	void(APIENTRY*glHint)(GLenum,GLenum);
	void(APIENTRY*glBlendFunc)(GLenum,GLenum);
	void(APIENTRY*glMatrixMode)(GLenum);
	void(APIENTRY*glLoadIdentity)();
	void(APIENTRY*glOrtho)(GLdouble,GLdouble,GLdouble,GLdouble,GLdouble,GLdouble);
	void(APIENTRY*glRotatef)(GLfloat,GLfloat,GLfloat,GLfloat);
	void(APIENTRY*glViewport)(GLint,GLint,GLsizei,GLsizei);
	void(APIENTRY*glFogf)(GLenum,GLfloat);
}
glfuncs;

void init_glfuncs(glfuncs* f)
{
	f->glBegin=get_funcaddr("glBegin");
	f->glEnd=get_funcaddr("glEnd");
	f->glVertex3f=get_funcaddr("glVertex3f");
	f->glClearColor=get_funcaddr("glClearColor");
	f->glClear=get_funcaddr("glClear");
	f->glDisable=get_funcaddr("glDisable");
	f->glEnable=get_funcaddr("glEnable");
	f->glColor4ub=get_funcaddr("glColor4ub");
	f->glPointSize=get_funcaddr("glPointSize");
	f->glHint=get_funcaddr("glHint");
	f->glBlendFunc=get_funcaddr("glBlendFunc");
	f->glMatrixMode=get_funcaddr("glMatrixMode");
	f->glLoadIdentity=get_funcaddr("glLoadIdentity");
	f->glOrtho=get_funcaddr("glOrtho");
	f->glRotatef=get_funcaddr("glRotatef");
	f->glViewport=get_funcaddr("glViewport");
	f->glFogf=get_funcaddr("glFogf");
}

#define NB_PIXELS 1000

int main(int argc,char *argv[])
{
	glfuncs f;
	int i;
	SDL_Event event;
	int done=0;
	GLfloat pixels[NB_PIXELS*3];
#ifdef _WIN32
	char *gl_library = "OpenGL32.DLL";
#else
	char *gl_library = "libGL.so.1";
#endif
	
	if (argv[1]) {
		gl_library = argv[1];
	}
	
	if (SDL_Init(SDL_INIT_VIDEO)<0)
	{
		printf("Unable to init SDL : %s\n",SDL_GetError());
		exit(1);
	}
	
	if (SDL_GL_SetAttribute(SDL_GL_DOUBLEBUFFER,1)<0)
	{
		printf("Unable to set GL attribute : %s\n",SDL_GetError());
		exit(1);
	}
	
	if (SDL_GL_LoadLibrary(gl_library)<0)
	{
		printf("Unable to dynamically open GL lib : %s\n",SDL_GetError());
		exit(1);
	}

	if (SDL_SetVideoMode(640,480,0,SDL_OPENGL)==NULL)
	{
		printf("Unable to open video mode : %s\n",SDL_GetError());
		exit(1);
	}

	init_glfuncs(&f);

	for(i=0;i<NB_PIXELS;i++)
	{
		pixels[3*i]=rand()%250-125;
		pixels[3*i+1]=rand()%250-125;
		pixels[3*i+2]=rand()%250-125;
	}
	
	f.glViewport(0,0,640,480);
	
	f.glMatrixMode(GL_PROJECTION);
	f.glLoadIdentity();
	f.glOrtho(-100,100,-100,100,-500,500);
	
	f.glMatrixMode(GL_MODELVIEW);
	f.glLoadIdentity();
	
	f.glEnable(GL_DEPTH_TEST);
	f.glDisable(GL_TEXTURE_2D);
	f.glEnable(GL_BLEND);
	f.glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
	
	f.glClearColor(0.0f,0.0f,0.0f,0.0f);
	f.glClear(GL_COLOR_BUFFER_BIT|GL_DEPTH_BUFFER_BIT);
	
	f.glEnable(GL_POINT_SMOOTH);
	f.glHint(GL_POINT_SMOOTH_HINT,GL_NICEST);
	f.glPointSize(5.0f);
	f.glEnable(GL_FOG);
	f.glFogf(GL_FOG_START,-500);
	f.glFogf(GL_FOG_END,500);
	f.glFogf(GL_FOG_DENSITY,0.005);
	
	do
	{
		f.glClear(GL_COLOR_BUFFER_BIT|GL_DEPTH_BUFFER_BIT);
		
		f.glRotatef(2.0,1.0,1.0,1.0);
		f.glRotatef(1.0,0.0,1.0,1.0);
		
		f.glColor4ub(255,255,255,255);
		f.glBegin(GL_POINTS);
		for(i=0;i<NB_PIXELS;i++)
		{
			f.glVertex3f(pixels[3*i],pixels[3*i+1],pixels[3*i+2]);
		}
		f.glEnd();
		SDL_GL_SwapBuffers();

		while(SDL_PollEvent(&event))
		{
			if(event.type & SDL_KEYDOWN)
				done=1;
		}

		SDL_Delay(20);
	}
	while(!done);
	
	SDL_Quit();
	return 0;
}

#else /* HAVE_OPENGL */

int main(int argc, char *argv[])
{
	printf("No OpenGL support on this system\n");
	return 1;
}

#endif /* HAVE_OPENGL */