// -- Written in C -- //
#include<stdio.h>
#include<stdlib.h>
#include<X11/X.h>
#include<X11/Xlib.h>
#include<GL/gl.h>
#include<GL/glx.h>
#include<GL/glu.h>
Display *dpy;
Window root;
GLint att[] = { GLX_RGBA, GLX_DEPTH_SIZE, 24, GLX_DOUBLEBUFFER, None };
XVisualInfo *vi;
Colormap cmap;
XSetWindowAttributes swa;
Window win;
GLXContext glc;
XWindowAttributes gwa;
XEvent xev;
void DrawAQuad() {
glClearColor(1.0, 1.0, 1.0, 1.0);
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
glMatrixMode(GL_PROJECTION);
glLoadIdentity();
glOrtho(-1., 1., -1., 1., 1., 20.);
glMatrixMode(GL_MODELVIEW);
glLoadIdentity();
gluLookAt(0., 0., 10., 0., 0., 0., 0., 1., 0.);
glBegin(GL_QUADS);
glColor3f(1., 0., 0.); glVertex3f(-.75, -.75, 0.);
glColor3f(0., 1., 0.); glVertex3f( .75, -.75, 0.);
glColor3f(0., 0., 1.); glVertex3f( .75, .75, 0.);
glColor3f(1., 1., 0.); glVertex3f(-.75, .75, 0.);
glEnd();
}
int main(int argc, char *argv[]) {
dpy = XOpenDisplay(NULL);
if(dpy == NULL) {
printf("\n\tcannot connect to X server\n\n");
exit(0);
}
root = DefaultRootWindow(dpy);
vi = glXChooseVisual(dpy, 0, att);
if(vi == NULL) {
printf("\n\tno appropriate visual found\n\n");
exit(0);
}
else {
printf("\n\tvisual %p selected\n", (void *)vi->visualid); /* %p creates hexadecimal output like in glxinfo */
}
cmap = XCreateColormap(dpy, root, vi->visual, AllocNone);
swa.colormap = cmap;
swa.event_mask = ExposureMask | KeyPressMask;
win = XCreateWindow(dpy, root, 0, 0, 600, 600, 0, vi->depth, InputOutput, vi->visual, CWColormap | CWEventMask, &swa);
XMapWindow(dpy, win);
XStoreName(dpy, win, "VERY SIMPLE APPLICATION");
glc = glXCreateContext(dpy, vi, NULL, GL_TRUE);
glXMakeCurrent(dpy, win, glc);
glEnable(GL_DEPTH_TEST);
while(1) {
XNextEvent(dpy, &xev);
if(xev.type == Expose) {
XGetWindowAttributes(dpy, win, &gwa);
glViewport(0, 0, gwa.width, gwa.height);
DrawAQuad();
glXSwapBuffers(dpy, win);
}
else if(xev.type == KeyPress) {
glXMakeCurrent(dpy, None, NULL);
glXDestroyContext(dpy, glc);
XDestroyWindow(dpy, win);
XCloseDisplay(dpy);
exit(0);
}
} /* this closes while(1) { */
} /* this is the } which closes int main(int argc, char *argv[]) { */
