Grazie a Zink, un layer basato su Mesa(una libreria famosa che serve anche all`intrepido Deck) che permette ad OpenGL di viaggiare sopra Vulkan e` possibile finalmente far girare i famosi ingranaggi del benchmark GlxGears anche con maggiore velocita. E tutto senza bisogno di aver scritto nuovo codice. Vediamo comunque per i piu curiosi l`esempio funzionante con i sorgenti ufficiali da github(codice scritto da BrianPaul nel 1999 e utilizzante le librerie OpenGL e Mesa):
#include <math.h>
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <X11/Xlib.h>
#include <X11/keysym.h>
#include <GL/gl.h>
#include <GL/glx.h>
#include <GL/glxext.h>
#ifndef GLX_MESA_swap_control
#define GLX_MESA_swap_control 1
typedef int (*PFNGLXGETSWAPINTERVALMESAPROC)(void);
#endif
#define BENCHMARK
#ifdef BENCHMARK
/* XXX this probably isn't very portable */
#include <sys/time.h>
#include <unistd.h>
/* return current time (in seconds) */
static double
current_time(void)
{
struct timeval tv;
#ifdef __VMS
(void) gettimeofday(&tv, NULL );
#else
struct timezone tz;
(void) gettimeofday(&tv, &tz);
#endif
return (double) tv.tv_sec + tv.tv_usec / 1000000.0;
}
#else /*BENCHMARK*/
/* dummy */
static double
current_time(void)
{
/* update this function for other platforms! */
static double t = 0.0;
static int warn = 1;
if (warn) {
fprintf(stderr, "Warning: current_time() not implemented!!\n");
warn = 0;
}
return t += 1.0;
}
#endif /*BENCHMARK*/
#ifndef M_PI
#define M_PI 3.14159265
#endif
/** Event handler results: */
#define NOP 0
#define EXIT 1
#define DRAW 2
static GLfloat view_rotx = 20.0, view_roty = 30.0, view_rotz = 0.0;
static GLint gear1, gear2, gear3;
static GLfloat angle = 0.0;
static GLboolean fullscreen = GL_FALSE; /* Create a single fullscreen window */
static GLboolean stereo = GL_FALSE; /* Enable stereo. */
static GLint samples = 0; /* Choose visual with at least N samples. */
static GLboolean animate = GL_TRUE; /* Animation */
static GLfloat eyesep = 5.0; /* Eye separation. */
static GLfloat fix_point = 40.0; /* Fixation point distance. */
static GLfloat left, right, asp; /* Stereo frustum params. */
/*
*
* Draw a gear wheel. You'll probably want to call this function when
* building a display list since we do a lot of trig here.
*
* Input: inner_radius - radius of hole at center
* outer_radius - radius at center of teeth
* width - width of gear
* teeth - number of teeth
* tooth_depth - depth of tooth
*/
static void
gear(GLfloat inner_radius, GLfloat outer_radius, GLfloat width,
GLint teeth, GLfloat tooth_depth)
{
GLint i;
GLfloat r0, r1, r2;
GLfloat angle, da;
GLfloat u, v, len;
r0 = inner_radius;
r1 = outer_radius - tooth_depth / 2.0;
r2 = outer_radius + tooth_depth / 2.0;
da = 2.0 * M_PI / teeth / 4.0;
glShadeModel(GL_FLAT);
glNormal3f(0.0, 0.0, 1.0);
/* draw front face */
glBegin(GL_QUAD_STRIP);
for (i = 0; i <= teeth; i++) {
angle = i * 2.0 * M_PI / teeth;
glVertex3f(r0 * cos(angle), r0 * sin(angle), width * 0.5);
glVertex3f(r1 * cos(angle), r1 * sin(angle), width * 0.5);
if (i < teeth) {
glVertex3f(r0 * cos(angle), r0 * sin(angle), width * 0.5);
glVertex3f(r1 * cos(angle + 3 * da), r1 * sin(angle + 3 * da),
width * 0.5);
}
}
glEnd();
/* draw front sides of teeth */
glBegin(GL_QUADS);
da = 2.0 * M_PI / teeth / 4.0;
for (i = 0; i < teeth; i++) {
angle = i * 2.0 * M_PI / teeth;
glVertex3f(r1 * cos(angle), r1 * sin(angle), width * 0.5);
glVertex3f(r2 * cos(angle + da), r2 * sin(angle + da), width * 0.5);
glVertex3f(r2 * cos(angle + 2 * da), r2 * sin(angle + 2 * da),
width * 0.5);
glVertex3f(r1 * cos(angle + 3 * da), r1 * sin(angle + 3 * da),
width * 0.5);
}
glEnd();
glNormal3f(0.0, 0.0, -1.0);
/* draw back face */
glBegin(GL_QUAD_STRIP);
for (i = 0; i <= teeth; i++) {
angle = i * 2.0 * M_PI / teeth;
glVertex3f(r1 * cos(angle), r1 * sin(angle), -width * 0.5);
glVertex3f(r0 * cos(angle), r0 * sin(angle), -width * 0.5);
if (i < teeth) {
glVertex3f(r1 * cos(angle + 3 * da), r1 * sin(angle + 3 * da),
-width * 0.5);
glVertex3f(r0 * cos(angle), r0 * sin(angle), -width * 0.5);
}
}
glEnd();
/* draw back sides of teeth */
glBegin(GL_QUADS);
da = 2.0 * M_PI / teeth / 4.0;
for (i = 0; i < teeth; i++) {
angle = i * 2.0 * M_PI / teeth;
glVertex3f(r1 * cos(angle + 3 * da), r1 * sin(angle + 3 * da),
-width * 0.5);
glVertex3f(r2 * cos(angle + 2 * da), r2 * sin(angle + 2 * da),
-width * 0.5);
glVertex3f(r2 * cos(angle + da), r2 * sin(angle + da), -width * 0.5);
glVertex3f(r1 * cos(angle), r1 * sin(angle), -width * 0.5);
}
glEnd();
/* draw outward faces of teeth */
glBegin(GL_QUAD_STRIP);
for (i = 0; i < teeth; i++) {
angle = i * 2.0 * M_PI / teeth;
glVertex3f(r1 * cos(angle), r1 * sin(angle), width * 0.5);
glVertex3f(r1 * cos(angle), r1 * sin(angle), -width * 0.5);
u = r2 * cos(angle + da) - r1 * cos(angle);
v = r2 * sin(angle + da) - r1 * sin(angle);
len = sqrt(u * u + v * v);
u /= len;
v /= len;
glNormal3f(v, -u, 0.0);
glVertex3f(r2 * cos(angle + da), r2 * sin(angle + da), width * 0.5);
glVertex3f(r2 * cos(angle + da), r2 * sin(angle + da), -width * 0.5);
glNormal3f(cos(angle), sin(angle), 0.0);
glVertex3f(r2 * cos(angle + 2 * da), r2 * sin(angle + 2 * da),
width * 0.5);
glVertex3f(r2 * cos(angle + 2 * da), r2 * sin(angle + 2 * da),
-width * 0.5);
u = r1 * cos(angle + 3 * da) - r2 * cos(angle + 2 * da);
v = r1 * sin(angle + 3 * da) - r2 * sin(angle + 2 * da);
glNormal3f(v, -u, 0.0);
glVertex3f(r1 * cos(angle + 3 * da), r1 * sin(angle + 3 * da),
width * 0.5);
glVertex3f(r1 * cos(angle + 3 * da), r1 * sin(angle + 3 * da),
-width * 0.5);
glNormal3f(cos(angle), sin(angle), 0.0);
}
glVertex3f(r1 * cos(0), r1 * sin(0), width * 0.5);
glVertex3f(r1 * cos(0), r1 * sin(0), -width * 0.5);
glEnd();
glShadeModel(GL_SMOOTH);
/* draw inside radius cylinder */
glBegin(GL_QUAD_STRIP);
for (i = 0; i <= teeth; i++) {
angle = i * 2.0 * M_PI / teeth;
glNormal3f(-cos(angle), -sin(angle), 0.0);
glVertex3f(r0 * cos(angle), r0 * sin(angle), -width * 0.5);
glVertex3f(r0 * cos(angle), r0 * sin(angle), width * 0.5);
}
glEnd();
}
static void
draw(void)
{
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
glPushMatrix();
glRotatef(view_rotx, 1.0, 0.0, 0.0);
glRotatef(view_roty, 0.0, 1.0, 0.0);
glRotatef(view_rotz, 0.0, 0.0, 1.0);
glPushMatrix();
glTranslatef(-3.0, -2.0, 0.0);
glRotatef(angle, 0.0, 0.0, 1.0);
glCallList(gear1);
glPopMatrix();
glPushMatrix();
glTranslatef(3.1, -2.0, 0.0);
glRotatef(-2.0 * angle - 9.0, 0.0, 0.0, 1.0);
glCallList(gear2);
glPopMatrix();
glPushMatrix();
glTranslatef(-3.1, 4.2, 0.0);
glRotatef(-2.0 * angle - 25.0, 0.0, 0.0, 1.0);
glCallList(gear3);
glPopMatrix();
glPopMatrix();
}
static void
draw_gears(void)
{
if (stereo) {
/* First left eye. */
glDrawBuffer(GL_BACK_LEFT);
glMatrixMode(GL_PROJECTION);
glLoadIdentity();
glFrustum(left, right, -asp, asp, 5.0, 60.0);
glMatrixMode(GL_MODELVIEW);
glPushMatrix();
glTranslated(+0.5 * eyesep, 0.0, 0.0);
draw();
glPopMatrix();
/* Then right eye. */
glDrawBuffer(GL_BACK_RIGHT);
glMatrixMode(GL_PROJECTION);
glLoadIdentity();
glFrustum(-right, -left, -asp, asp, 5.0, 60.0);
glMatrixMode(GL_MODELVIEW);
glPushMatrix();
glTranslated(-0.5 * eyesep, 0.0, 0.0);
draw();
glPopMatrix();
}
else {
draw();
}
}
/** Draw single frame, do SwapBuffers, compute FPS */
static void
draw_frame(Display *dpy, Window win)
{
static int frames = 0;
static double tRot0 = -1.0, tRate0 = -1.0;
double dt, t = current_time();
if (tRot0 < 0.0)
tRot0 = t;
dt = t - tRot0;
tRot0 = t;
if (animate) {
/* advance rotation for next frame */
angle += 70.0 * dt; /* 70 degrees per second */
if (angle > 3600.0)
angle -= 3600.0;
}
draw_gears();
glXSwapBuffers(dpy, win);
frames++;
if (tRate0 < 0.0)
tRate0 = t;
if (t - tRate0 >= 5.0) {
GLfloat seconds = t - tRate0;
GLfloat fps = frames / seconds;
printf("%d frames in %3.1f seconds = %6.3f FPS\n", frames, seconds,
fps);
fflush(stdout);
tRate0 = t;
frames = 0;
}
}
/* new window size or exposure */
static void
reshape(int width, int height)
{
glViewport(0, 0, (GLint) width, (GLint) height);
if (stereo) {
GLfloat w;
asp = (GLfloat) height / (GLfloat) width;
w = fix_point * (1.0 / 5.0);
left = -5.0 * ((w - 0.5 * eyesep) / fix_point);
right = 5.0 * ((w + 0.5 * eyesep) / fix_point);
}
else {
GLfloat h = (GLfloat) height / (GLfloat) width;
glMatrixMode(GL_PROJECTION);
glLoadIdentity();
glFrustum(-1.0, 1.0, -h, h, 5.0, 60.0);
}
glMatrixMode(GL_MODELVIEW);
glLoadIdentity();
glTranslatef(0.0, 0.0, -40.0);
}
static void
init(void)
{
static GLfloat pos[4] = { 5.0, 5.0, 10.0, 0.0 };
static GLfloat red[4] = { 0.8, 0.1, 0.0, 1.0 };
static GLfloat green[4] = { 0.0, 0.8, 0.2, 1.0 };
static GLfloat blue[4] = { 0.2, 0.2, 1.0, 1.0 };
glLightfv(GL_LIGHT0, GL_POSITION, pos);
glEnable(GL_CULL_FACE);
glEnable(GL_LIGHTING);
glEnable(GL_LIGHT0);
glEnable(GL_DEPTH_TEST);
/* make the gears */
gear1 = glGenLists(1);
glNewList(gear1, GL_COMPILE);
glMaterialfv(GL_FRONT, GL_AMBIENT_AND_DIFFUSE, red);
gear(1.0, 4.0, 1.0, 20, 0.7);
glEndList();
gear2 = glGenLists(1);
glNewList(gear2, GL_COMPILE);
glMaterialfv(GL_FRONT, GL_AMBIENT_AND_DIFFUSE, green);
gear(0.5, 2.0, 2.0, 10, 0.7);
glEndList();
gear3 = glGenLists(1);
glNewList(gear3, GL_COMPILE);
glMaterialfv(GL_FRONT, GL_AMBIENT_AND_DIFFUSE, blue);
gear(1.3, 2.0, 0.5, 10, 0.7);
glEndList();
glEnable(GL_NORMALIZE);
}
/**
* Remove window border/decorations.
*/
static void
no_border( Display *dpy, Window w)
{
static const unsigned MWM_HINTS_DECORATIONS = (1 << 1);
static const int PROP_MOTIF_WM_HINTS_ELEMENTS = 5;
typedef struct
{
unsigned long flags;
unsigned long functions;
unsigned long decorations;
long inputMode;
unsigned long status;
} PropMotifWmHints;
PropMotifWmHints motif_hints;
Atom prop, proptype;
unsigned long flags = 0;
/* setup the property */
motif_hints.flags = MWM_HINTS_DECORATIONS;
motif_hints.decorations = flags;
/* get the atom for the property */
prop = XInternAtom( dpy, "_MOTIF_WM_HINTS", True );
if (!prop) {
/* something went wrong! */
return;
}
/* not sure this is correct, seems to work, XA_WM_HINTS didn't work */
proptype = prop;
XChangeProperty( dpy, w, /* display, window */
prop, proptype, /* property, type */
32, /* format: 32-bit datums */
PropModeReplace, /* mode */
(unsigned char *) &motif_hints, /* data */
PROP_MOTIF_WM_HINTS_ELEMENTS /* nelements */
);
}
/*
* Create an RGB, double-buffered window.
* Return the window and context handles.
*/
static void
make_window( Display *dpy, const char *name,
int x, int y, int width, int height,
Window *winRet, GLXContext *ctxRet, VisualID *visRet)
{
int attribs[64];
int i = 0;
int scrnum;
XSetWindowAttributes attr;
unsigned long mask;
Window root;
Window win;
GLXContext ctx;
XVisualInfo *visinfo;
/* Singleton attributes. */
attribs[i++] = GLX_RGBA;
attribs[i++] = GLX_DOUBLEBUFFER;
if (stereo)
attribs[i++] = GLX_STEREO;
/* Key/value attributes. */
attribs[i++] = GLX_RED_SIZE;
attribs[i++] = 1;
attribs[i++] = GLX_GREEN_SIZE;
attribs[i++] = 1;
attribs[i++] = GLX_BLUE_SIZE;
attribs[i++] = 1;
attribs[i++] = GLX_DEPTH_SIZE;
attribs[i++] = 1;
if (samples > 0) {
attribs[i++] = GLX_SAMPLE_BUFFERS;
attribs[i++] = 1;
attribs[i++] = GLX_SAMPLES;
attribs[i++] = samples;
}
attribs[i++] = None;
scrnum = DefaultScreen( dpy );
root = RootWindow( dpy, scrnum );
visinfo = glXChooseVisual(dpy, scrnum, attribs);
if (!visinfo) {
printf("Error: couldn't get an RGB, Double-buffered");
if (stereo)
printf(", Stereo");
if (samples > 0)
printf(", Multisample");
printf(" visual\n");
exit(1);
}
/* window attributes */
attr.background_pixel = 0;
attr.border_pixel = 0;
attr.colormap = XCreateColormap( dpy, root, visinfo->visual, AllocNone);
attr.event_mask = StructureNotifyMask | ExposureMask | KeyPressMask;
/* XXX this is a bad way to get a borderless window! */
mask = CWBackPixel | CWBorderPixel | CWColormap | CWEventMask;
win = XCreateWindow( dpy, root, x, y, width, height,
0, visinfo->depth, InputOutput,
visinfo->visual, mask, &attr );
if (fullscreen)
no_border(dpy, win);
/* set hints and properties */
{
XSizeHints sizehints;
sizehints.x = x;
sizehints.y = y;
sizehints.width = width;
sizehints.height = height;
sizehints.flags = USSize | USPosition;
XSetNormalHints(dpy, win, &sizehints);
XSetStandardProperties(dpy, win, name, name,
None, (char **)NULL, 0, &sizehints);
}
ctx = glXCreateContext( dpy, visinfo, NULL, True );
if (!ctx) {
printf("Error: glXCreateContext failed\n");
exit(1);
}
*winRet = win;
*ctxRet = ctx;
*visRet = visinfo->visualid;
XFree(visinfo);
}
/**
* Determine whether or not a GLX extension is supported.
*/
static int
is_glx_extension_supported(Display *dpy, const char *query)
{
const int scrnum = DefaultScreen(dpy);
const char *glx_extensions = NULL;
const size_t len = strlen(query);
const char *ptr;
if (glx_extensions == NULL) {
glx_extensions = glXQueryExtensionsString(dpy, scrnum);
}
ptr = strstr(glx_extensions, query);
return ((ptr != NULL) && ((ptr[len] == ' ') || (ptr[len] == '\0')));
}
/**
* Attempt to determine whether or not the display is synched to vblank.
*/
static void
query_vsync(Display *dpy, GLXDrawable drawable)
{
int interval = 0;
#if defined(GLX_EXT_swap_control)
if (is_glx_extension_supported(dpy, "GLX_EXT_swap_control")) {
unsigned int tmp = -1;
glXQueryDrawable(dpy, drawable, GLX_SWAP_INTERVAL_EXT, &tmp);
interval = tmp;
} else
#endif
if (is_glx_extension_supported(dpy, "GLX_MESA_swap_control")) {
PFNGLXGETSWAPINTERVALMESAPROC pglXGetSwapIntervalMESA =
(PFNGLXGETSWAPINTERVALMESAPROC)
glXGetProcAddressARB((const GLubyte *) "glXGetSwapIntervalMESA");
interval = (*pglXGetSwapIntervalMESA)();
} else if (is_glx_extension_supported(dpy, "GLX_SGI_swap_control")) {
/* The default swap interval with this extension is 1. Assume that it
* is set to the default.
*
* Many Mesa-based drivers default to 0, but all of these drivers also
* export GLX_MESA_swap_control. In that case, this branch will never
* be taken, and the correct result should be reported.
*/
interval = 1;
}
if (interval > 0) {
printf("Running synchronized to the vertical refresh. The framerate should be\n");
if (interval == 1) {
printf("approximately the same as the monitor refresh rate.\n");
} else if (interval > 1) {
printf("approximately 1/%d the monitor refresh rate.\n",
interval);
}
}
}
/**
* Handle one X event.
* \return NOP, EXIT or DRAW
*/
static int
handle_event(Display *dpy, Window win, XEvent *event)
{
(void) dpy;
(void) win;
switch (event->type) {
case Expose:
return DRAW;
case ConfigureNotify:
reshape(event->xconfigure.width, event->xconfigure.height);
break;
case KeyPress:
{
char buffer[10];
int code;
code = XLookupKeysym(&event->xkey, 0);
if (code == XK_Left) {
view_roty += 5.0;
}
else if (code == XK_Right) {
view_roty -= 5.0;
}
else if (code == XK_Up) {
view_rotx += 5.0;
}
else if (code == XK_Down) {
view_rotx -= 5.0;
}
else {
XLookupString(&event->xkey, buffer, sizeof(buffer),
NULL, NULL);
if (buffer[0] == 27) {
/* escape */
return EXIT;
}
else if (buffer[0] == 'a' || buffer[0] == 'A') {
animate = !animate;
}
}
return DRAW;
}
}
return NOP;
}
static void
event_loop(Display *dpy, Window win)
{
while (1) {
int op;
while (!animate || XPending(dpy) > 0) {
XEvent event;
XNextEvent(dpy, &event);
op = handle_event(dpy, win, &event);
if (op == EXIT)
return;
else if (op == DRAW)
break;
}
draw_frame(dpy, win);
}
}
static void
usage(void)
{
printf("Usage:\n");
printf(" -display <displayname> set the display to run on\n");
printf(" -stereo run in stereo mode\n");
printf(" -samples N run in multisample mode with at least N samples\n");
printf(" -fullscreen run in fullscreen mode\n");
printf(" -info display OpenGL renderer info\n");
printf(" -geometry WxH+X+Y window geometry\n");
}
int
main(int argc, char *argv[])
{
unsigned int winWidth = 300, winHeight = 300;
int x = 0, y = 0;
Display *dpy;
Window win;
GLXContext ctx;
char *dpyName = NULL;
GLboolean printInfo = GL_FALSE;
VisualID visId;
int i;
for (i = 1; i < argc; i++) {
if (strcmp(argv[i], "-display") == 0) {
dpyName = argv[i+1];
i++;
}
else if (strcmp(argv[i], "-info") == 0) {
printInfo = GL_TRUE;
}
else if (strcmp(argv[i], "-stereo") == 0) {
stereo = GL_TRUE;
}
else if (i < argc-1 && strcmp(argv[i], "-samples") == 0) {
samples = strtod(argv[i+1], NULL );
++i;
}
else if (strcmp(argv[i], "-fullscreen") == 0) {
fullscreen = GL_TRUE;
}
else if (i < argc-1 && strcmp(argv[i], "-geometry") == 0) {
XParseGeometry(argv[i+1], &x, &y, &winWidth, &winHeight);
i++;
}
else {
usage();
return -1;
}
}
dpy = XOpenDisplay(dpyName);
if (!dpy) {
printf("Error: couldn't open display %s\n",
dpyName ? dpyName : getenv("DISPLAY"));
return -1;
}
if (fullscreen) {
int scrnum = DefaultScreen(dpy);
x = 0; y = 0;
winWidth = DisplayWidth(dpy, scrnum);
winHeight = DisplayHeight(dpy, scrnum);
}
make_window(dpy, "glxgears", x, y, winWidth, winHeight, &win, &ctx, &visId);
XMapWindow(dpy, win);
glXMakeCurrent(dpy, win, ctx);
query_vsync(dpy, win);
if (printInfo) {
printf("GL_RENDERER = %s\n", (char *) glGetString(GL_RENDERER));
printf("GL_VERSION = %s\n", (char *) glGetString(GL_VERSION));
printf("GL_VENDOR = %s\n", (char *) glGetString(GL_VENDOR));
printf("GL_EXTENSIONS = %s\n", (char *) glGetString(GL_EXTENSIONS));
printf("VisualID %d, 0x%x\n", (int) visId, (int) visId);
}
init();
/* Set initial projection/viewing transformation.
* We can't be sure we'll get a ConfigureNotify event when the window
* first appears.
*/
reshape(winWidth, winHeight);
event_loop(dpy, win);
glDeleteLists(gear1, 1);
glDeleteLists(gear2, 1);
glDeleteLists(gear3, 1);
glXMakeCurrent(dpy, None, NULL);
glXDestroyContext(dpy, ctx);
XDestroyWindow(dpy, win);
XCloseDisplay(dpy);
return 0;
}
Il principio di funzionamento di Zink e` semplice: le primitive sono scritte su un buffer e si utilizzano i geometry shader per ricostruire linee e punti(da FOSDEM video).
Links
Glxgears test by Blumenkratz
