Ein X Window System OpenGL-Programm

Das folgende Programm ist ein X Window System OpenGL-Programm mit dem gleichen OpenGL-Code, der im AUXEDEMO verwendet wird. C-Beispielprogramm, das mit dem Microsoft Platform SDK bereitgestellt wird. Vergleichen Sie dieses Programm mit dem Windows OpenGL-Programm in The Program Ported to Windows.

/* 
 * Example of an X Window System OpenGL program.   
 * OpenGL code is taken from auxdemo.c in the Platform SDK 
 */ 
#include <GL/glx.h> 
#include <GL/gl.h> 
#include <GL/glu.h> 
#include <X11/keysym.h> 
#include <X11/Xlib.h> 
#include <X11/Xutil.h> 
#include <stdio.h> 
 
/* X globals, defines, and prototypes */ 
Display *dpy; 
Window glwin; 
static int attributes[] = {GLX_DEPTH_SIZE, 16, GLX_DOUBLEBUFFER, None}; 
 
#define SWAPBUFFERS glXSwapBuffers(dpy, glwin) 
#define BLACK_INDEX     0 
#define RED_INDEX       1 
#define GREEN_INDEX     2 
#define BLUE_INDEX      4 
#define WIDTH           300 
#define HEIGHT          200 
 
 
/* OpenGL globals, defines, and prototypes */ 
GLfloat latitude, longitude, latinc, longinc; 
GLdouble radius; 
 
#define GLOBE    1 
#define CYLINDER 2 
#define CONE     3 
 
GLvoid resize(GLsizei, GLsizei); 
GLvoid initializeGL(GLsizei, GLsizei); 
GLvoid drawScene(GLvoid); 
void polarView( GLdouble, GLdouble, GLdouble, GLdouble); 
 
static Bool WaitForMapNotify(Display *d, XEvent *e, char *arg) 
{ 
    if ((e->type == MapNotify) && (e->xmap.window == (Window)arg)) { 
    return GL_TRUE; 
    } 
    return GL_FALSE; 
} 
 
void 
main(int argc, char **argv) 
{ 
    XVisualInfo    *vi; 
    Colormap        cmap; 
    XSetWindowAttributes swa; 
    GLXContext      cx; 
    XEvent          event; 
    GLboolean       needRedraw = GL_FALSE, recalcModelView = GL_TRUE; 
    int             dummy; 
 
    dpy = XOpenDisplay(NULL); 
    if (dpy == NULL){ 
        fprintf(stderr, "could not open display\n"); 
        exit(1); 
    } 
 
    if(!glXQueryExtension(dpy, &dummy, &dummy)){ 
        fprintf(stderr, "could not open display"); 
        exit(1); 
    } 
 
    /* find an OpenGL-capable Color Index visual with depth buffer */ 
    vi = glXChooseVisual(dpy, DefaultScreen(dpy), attributes); 
    if (vi == NULL) { 
        fprintf(stderr, "could not get visual\n"); 
        exit(1); 
    } 
 
    /* create an OpenGL rendering context */ 
    cx = glXCreateContext(dpy, vi,  None, GL_TRUE); 
    if (cx == NULL) { 
        fprintf(stderr, "could not create rendering context\n"); 
        exit(1); 
    } 
 
    /* create an X colormap since probably not using default visual */ 
    cmap = XCreateColormap(dpy, RootWindow(dpy, vi->screen),  
                                vi->visual, AllocNone); 
    swa.colormap = cmap; 
    swa.border_pixel = 0; 
    swa.event_mask = ExposureMask | KeyPressMask | StructureNotifyMask; 
    glwin = XCreateWindow(dpy, RootWindow(dpy, vi->screen), 0, 0, WIDTH, 
                        HEIGHT, 0, vi->depth, InputOutput, vi->visual, 
                        CWBorderPixel | CWColormap | CWEventMask, &swa); 
    XSetStandardProperties(dpy, glwin, "xogl", "xogl", None, argv,  
                                argc, NULL); 
 
    glXMakeCurrent(dpy, glwin, cx); 
 
    XMapWindow(dpy, glwin); 
    XIfEvent(dpy,  &event,  WaitForMapNotify,  (char *)glwin); 
     
    initializeGL(WIDTH, HEIGHT); 
    resize(WIDTH, HEIGHT); 
    
    /* Animation loop */ 
    while (1) { 
    KeySym key; 
 
    while (XPending(dpy)) { 
        XNextEvent(dpy, &event); 
        switch (event.type) { 
        case KeyPress: 
                XLookupString((XKeyEvent *)&event, NULL, 0, &key, NULL); 
        switch (key) { 
        case XK_Left: 
            longinc += 0.5; 
            break; 
        case XK_Right: 
            longinc -= 0.5; 
            break; 
        case XK_Up: 
            latinc += 0.5; 
            break; 
        case XK_Down: 
            latinc -= 0.5; 
            break; 
        } 
        break; 
        case ConfigureNotify: 
        resize(event.xconfigure.width, event.xconfigure.height); 
        break; 
        } 
    } 
    drawScene(); 
    } 
} 
 
/* OpenGL code */ 
 
GLvoid resize( GLsizei width, GLsizei height ) 
{ 
    GLfloat aspect; 
 
    glViewport( 0, 0, width, height ); 
 
    aspect = (GLfloat) width / height; 
 
    glMatrixMode( GL_PROJECTION ); 
    glLoadIdentity(); 
    gluPerspective( 45.0, aspect, 3.0, 7.0 ); 
    glMatrixMode( GL_MODELVIEW ); 
}     
 
GLvoid createObjects() 
{ 
    GLUquadricObj *quadObj; 
 
    glNewList(GLOBE, GL_COMPILE); 
        quadObj = gluNewQuadric (); 
        gluQuadricDrawStyle (quadObj, GLU_LINE); 
        gluSphere (quadObj, 1.5, 16, 16); 
    glEndList(); 
 
    glNewList(CONE, GL_COMPILE); 
        quadObj = gluNewQuadric (); 
        gluQuadricDrawStyle (quadObj, GLU_FILL); 
        gluQuadricNormals (quadObj, GLU_SMOOTH); 
        gluCylinder(quadObj, 0.3, 0.0, 0.6, 15, 10); 
    glEndList(); 
 
    glNewList(CYLINDER, GL_COMPILE); 
        glPushMatrix (); 
        glRotatef ((GLfloat)90.0, (GLfloat)1.0, (GLfloat)0.0, (GLfloat)0.0); 
        glTranslatef ((GLfloat)0.0, (GLfloat)0.0, (GLfloat)-1.0); 
        quadObj = gluNewQuadric (); 
        gluQuadricDrawStyle (quadObj, GLU_FILL); 
        gluQuadricNormals (quadObj, GLU_SMOOTH); 
        gluCylinder (quadObj, 0.3, 0.3, 0.6, 12, 2); 
        glPopMatrix (); 
    glEndList(); 
} 
 
GLvoid initializeGL(GLsizei width, GLsizei height) 
{ 
    GLfloat    maxObjectSize, aspect; 
    GLdouble    near_plane, far_plane; 
 
    glClearIndex( (GLfloat)BLACK_INDEX); 
    glClearDepth( 1.0 ); 
 
    glEnable(GL_DEPTH_TEST); 
 
    glMatrixMode( GL_PROJECTION ); 
    aspect = (GLfloat) width / height; 
    gluPerspective( 45.0, aspect, 3.0, 7.0 ); 
    glMatrixMode( GL_MODELVIEW ); 
 
    near_plane = 3.0; 
    far_plane = 7.0; 
    maxObjectSize = 3.0F; 
    radius = near_plane + maxObjectSize/2.0; 
 
    latitude = 0.0F; 
    longitude = 0.0F; 
    latinc = 6.0F; 
    longinc = 2.5F; 
 
    createObjects(); 
} 
 
void polarView(GLdouble radius, GLdouble twist, GLdouble latitude, 
           GLdouble longitude) 
{ 
    glTranslated(0.0, 0.0, -radius); 
    glRotated(-twist, 0.0, 0.0, 1.0); 
    glRotated(-latitude, 1.0, 0.0, 0.0); 
    glRotated(longitude, 0.0, 0.0, 1.0);      
 
} 
 
GLvoid drawScene(GLvoid) 
{ 
    glClear( GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT ); 
 
    glPushMatrix(); 
 
        latitude += latinc; 
        longitude += longinc; 
 
        polarView( radius, 0, latitude, longitude ); 
 
        glIndexi(RED_INDEX); 
        glCallList(CONE); 
 
        glIndexi(BLUE_INDEX); 
        glCallList(GLOBE); 
 
        glIndexi(GREEN_INDEX); 
        glPushMatrix(); 
            glTranslatef(0.8F, -0.65F, 0.0F); 
            glRotatef(30.0F, 1.0F, 0.5F, 1.0F); 
            glCallList(CYLINDER); 
        glPopMatrix(); 
 
    glPopMatrix(); 
 
    SWAPBUFFERS; 
}