This repository has been archived by the owner on Feb 11, 2021. It is now read-only.
testdyngles.c
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/*
* 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 __IPHONEOS__
#define HAVE_OPENGLES
#endif
#ifdef HAVE_OPENGLES
#include "SDL_opengles.h"
/* Call this instead of exit(), so we can clean up SDL: atexit() is evil. */
static void
quit(int rc)
{
SDL_Quit();
exit(rc);
}
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);
quit(1);
}
return NULL;
}
typedef struct
{
void (APIENTRY * glEnableClientState) (GLenum array);
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void (APIENTRY * glDisableClientState) (GLenum array);
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void (APIENTRY * glVertexPointer) (GLint size, GLenum type,
GLsizei stride,
const GLvoid * pointer);
void (APIENTRY * glDrawArrays) (GLenum mode, GLint first, GLsizei count);
void (APIENTRY * glClearColor) (GLfloat, GLfloat, GLfloat, GLfloat);
void (APIENTRY * glClear) (GLbitfield);
void (APIENTRY * glDisable) (GLenum);
void (APIENTRY * glEnable) (GLenum);
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void (APIENTRY * glColor4f) (GLfloat, GLfloat, GLfloat, GLfloat);
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void (APIENTRY * glPointSize) (GLfloat);
void (APIENTRY * glHint) (GLenum, GLenum);
void (APIENTRY * glBlendFunc) (GLenum, GLenum);
void (APIENTRY * glMatrixMode) (GLenum);
void (APIENTRY * glLoadIdentity) ();
void (APIENTRY * glOrthof) (GLfloat, GLfloat, GLfloat, GLfloat,
GLfloat, GLfloat);
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->glEnableClientState = get_funcaddr("glEnableClientState");
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f->glDisableClientState = get_funcaddr("glDisableClientState");
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f->glVertexPointer = get_funcaddr("glVertexPointer");
f->glDrawArrays = get_funcaddr("glDrawArrays");
f->glClearColor = get_funcaddr("glClearColor");
f->glClear = get_funcaddr("glClear");
f->glDisable = get_funcaddr("glDisable");
f->glEnable = get_funcaddr("glEnable");
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f->glColor4f = get_funcaddr("glColor4f");
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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->glOrthof = get_funcaddr("glOrthof");
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];
const char *gl_library = NULL; /* Use the default GL library */
int video_w, video_h;
/* you may want to change these according to the platform */
video_w = 320;
video_h = 480;
if (argv[1]) {
gl_library = argv[1];
}
if (SDL_Init(SDL_INIT_VIDEO) < 0) {
printf("Unable to init SDL : %s\n", SDL_GetError());
return (1);
}
if (SDL_GL_LoadLibrary(gl_library) < 0) {
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printf("Unable to dynamically open GL ES lib : %s\n", SDL_GetError());
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quit(1);
}
if (SDL_SetVideoMode(video_h, video_w, 0, SDL_OPENGL) == NULL) {
printf("Unable to open video mode : %s\n", SDL_GetError());
quit(1);
}
/* Set the window manager title bar */
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SDL_WM_SetCaption("SDL Dynamic OpenGL ES Loading Test", "testdyngles");
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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;
}
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f.glViewport(0, 0, video_w, video_h);
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f.glMatrixMode(GL_PROJECTION);
f.glLoadIdentity();
f.glOrthof(-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);
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f.glPointSize(1.0f);
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f.glEnable(GL_FOG);
f.glFogf(GL_FOG_START, -500);
f.glFogf(GL_FOG_END, 500);
f.glFogf(GL_FOG_DENSITY, 0.005);
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f.glVertexPointer(3, GL_FLOAT, 0, pixels);
f.glEnableClientState(GL_VERTEX_ARRAY);
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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);
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f.glColor4f(1.0, 1.0, 1.0, 1.0);
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f.glDrawArrays(GL_POINTS, 0, NB_PIXELS);
SDL_GL_SwapBuffers();
while (SDL_PollEvent(&event)) {
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if (event.type == SDL_QUIT)
done = 1;
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if (event.type == SDL_KEYDOWN)
done = 1;
}
SDL_Delay(20);
}
while (!done);
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f.glDisableClientState(GL_VERTEX_ARRAY);
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SDL_Quit();
return 0;
}
#else /* HAVE_OPENGLES */
int
main(int argc, char *argv[])
{
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printf("No OpenGL ES support on this system\n");
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return 1;
}
#endif /* HAVE_OPENGLES */