/*
 * Copyright (C) 2000  Brian Paul   All Rights Reserved.
 * Copyright (C) 2018  D. R. Commander   All Rights Reserved.
 *
 * Permission is hereby granted, free of charge, to any person obtaining a
 * copy of this software and associated documentation files (the "Software"),
 * to deal in the Software without restriction, including without limitation
 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
 * and/or sell copies of the Software, and to permit persons to whom the
 * Software is furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included
 * in all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
 * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
 * BRIAN PAUL BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN
 * AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
 * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 */


/*
 * This program tests GLX thread safety.
 * Command line options:
 *  -p                       Open a display connection for each thread
 *  -l                       Enable application-side locking
 *  -n <num threads>         Number of threads to create (default is 2)
 *  -display <display name>  Specify X display (default is $DISPLAY)
 *  -t                       Use texture mapping
 *
 * Brian Paul  20 July 2000
 */


/*
 * Notes:
 * - Each thread gets its own GLX context.
 *
 * - The GLX contexts share texture objects.
 *
 * - When 't' is pressed to update the texture image, the window/thread which
 *   has input focus is signalled to change the texture.  The other threads
 *   should see the updated texture the next time they call glBindTexture.
 */


#include <assert.h>
#include <GL/gl.h>
#include <GL/glx.h>
#include <math.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <pthread.h>
#include <X11/keysym.h>


/*
 * Each window/thread/context:
 */
struct winthread {
   Display *Dpy;
   int Index;
   pthread_t Thread;
   Window Win;
   GLXContext Context;
   float Angle;
   int WinWidth, WinHeight;
   GLboolean NewSize;
   GLboolean Initialized;
   GLboolean MakeNewTexture;
};


#define MAX_WINTHREADS 100
static struct winthread WinThreads[MAX_WINTHREADS];
static int NumWinThreads = 0;
static volatile GLboolean ExitFlag = GL_FALSE;

static GLboolean MultiDisplays = 0;
static GLboolean Locking = 0;
static GLboolean Texture = GL_FALSE;
static GLuint TexObj = 12;
static GLboolean Animate = GL_TRUE;

static pthread_mutex_t Mutex;
static pthread_cond_t CondVar;
static pthread_mutex_t CondMutex;


/* These macros were added for VirtualGL.  When using the X11 Transport, VGL
   makes calls to X[Shm]PutImage() within the body of glXSwapBuffers(), and
   sometimes within the body of glXMakeCurrent() as well.  Thus, some form of
   locking is always necessary when sharing the same display connection among
   multiple threads.  Passing -l to this program causes it to use pthreads for
   locking instead of XLockDisplay()/XUnlockDisplay(). */

#define LOCK(dpy) \
   if (Locking) \
      pthread_mutex_lock(&Mutex); \
   else if (!MultiDisplays) \
      XLockDisplay(dpy) \

#define UNLOCK(dpy) \
   if (Locking) \
      pthread_mutex_unlock(&Mutex); \
   else if (!MultiDisplays)  \
      XUnlockDisplay(dpy) \


static void
Error(const char *msg)
{
   fprintf(stderr, "Error: %s\n", msg);
   exit(1);
}


static void
signal_redraw(void)
{
   pthread_mutex_lock(&CondMutex);
   pthread_cond_broadcast(&CondVar);
   pthread_mutex_unlock(&CondMutex);
}


static void
MakeNewTexture(struct winthread *wt)
{
#define TEX_SIZE 128
   static float step = 0.0;
   GLfloat image[TEX_SIZE][TEX_SIZE][4];
   GLint width;
   int i, j;

   for (j = 0; j < TEX_SIZE; j++) {
      for (i = 0; i < TEX_SIZE; i++) {
         float dt = 5.0 * (j - 0.5 * TEX_SIZE) / TEX_SIZE;
         float ds = 5.0 * (i - 0.5 * TEX_SIZE) / TEX_SIZE;
         float r = dt * dt + ds * ds + step;
         image[j][i][0] =
         image[j][i][1] =
         image[j][i][2] = 0.75 + 0.25 * cos(r);
         image[j][i][3] = 1.0;
      }
   }

   step += 0.5;

   glBindTexture(GL_TEXTURE_2D, TexObj);

   glGetTexLevelParameteriv(GL_TEXTURE_2D, 0, GL_TEXTURE_WIDTH, &width);
   if (width) {
      assert(width == TEX_SIZE);
      /* sub-tex replace */
      glTexSubImage2D(GL_TEXTURE_2D, 0, 0, 0, TEX_SIZE, TEX_SIZE,
                   GL_RGBA, GL_FLOAT, image);
   }
   else {
      /* create new */
      glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
      glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);

      glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, TEX_SIZE, TEX_SIZE, 0,
                   GL_RGBA, GL_FLOAT, image);
   }
}



/* draw a colored cube */
static void
draw_object(void)
{
   glPushMatrix();
   glScalef(0.75, 0.75, 0.75);

   glColor3f(1, 0, 0);

   if (Texture) {
      glBindTexture(GL_TEXTURE_2D, TexObj);
      glEnable(GL_TEXTURE_2D);
   }
   else {
      glDisable(GL_TEXTURE_2D);
   }

   glBegin(GL_QUADS);

   /* -X */
   glColor3f(0, 1, 1);
   glTexCoord2f(0, 0);  glVertex3f(-1, -1, -1);
   glTexCoord2f(1, 0);  glVertex3f(-1,  1, -1);
   glTexCoord2f(1, 1);  glVertex3f(-1,  1,  1);
   glTexCoord2f(0, 1);  glVertex3f(-1, -1,  1);

   /* +X */
   glColor3f(1, 0, 0);
   glTexCoord2f(0, 0);  glVertex3f(1, -1, -1);
   glTexCoord2f(1, 0);  glVertex3f(1,  1, -1);
   glTexCoord2f(1, 1);  glVertex3f(1,  1,  1);
   glTexCoord2f(0, 1);  glVertex3f(1, -1,  1);

   /* -Y */
   glColor3f(1, 0, 1);
   glTexCoord2f(0, 0);  glVertex3f(-1, -1, -1);
   glTexCoord2f(1, 0);  glVertex3f( 1, -1, -1);
   glTexCoord2f(1, 1);  glVertex3f( 1, -1,  1);
   glTexCoord2f(0, 1);  glVertex3f(-1, -1,  1);

   /* +Y */
   glColor3f(0, 1, 0);
   glTexCoord2f(0, 0);  glVertex3f(-1, 1, -1);
   glTexCoord2f(1, 0);  glVertex3f( 1, 1, -1);
   glTexCoord2f(1, 1);  glVertex3f( 1, 1,  1);
   glTexCoord2f(0, 1);  glVertex3f(-1, 1,  1);

   /* -Z */
   glColor3f(1, 1, 0);
   glTexCoord2f(0, 0);  glVertex3f(-1, -1, -1);
   glTexCoord2f(1, 0);  glVertex3f( 1, -1, -1);
   glTexCoord2f(1, 1);  glVertex3f( 1,  1, -1);
   glTexCoord2f(0, 1);  glVertex3f(-1,  1, -1);

   /* +Y */
   glColor3f(0, 0, 1);
   glTexCoord2f(0, 0);  glVertex3f(-1, -1, 1);
   glTexCoord2f(1, 0);  glVertex3f( 1, -1, 1);
   glTexCoord2f(1, 1);  glVertex3f( 1,  1, 1);
   glTexCoord2f(0, 1);  glVertex3f(-1,  1, 1);

   glEnd();

   glPopMatrix();
}


/* signal resize of given window */
static void
resize(struct winthread *wt, int w, int h)
{
   wt->NewSize = GL_TRUE;
   wt->WinWidth = w;
   wt->WinHeight = h;
   if (!Animate)
      signal_redraw();
}


/*
 * We have an instance of this for each thread.
 */
static void
draw_loop(struct winthread *wt)
{
   while (!ExitFlag) {

      LOCK(wt->Dpy);

      glXMakeCurrent(wt->Dpy, wt->Win, wt->Context);
      if (!wt->Initialized) {
         printf("glthreads: %d: GL_RENDERER = %s\n", wt->Index,
                (char *) glGetString(GL_RENDERER));
         if (Texture /*&& wt->Index == 0*/) {
            MakeNewTexture(wt);
         }
         wt->Initialized = GL_TRUE;
      }

      UNLOCK(wt->Dpy);

      glEnable(GL_DEPTH_TEST);

      if (wt->NewSize) {
         GLfloat w = (float) wt->WinWidth / (float) wt->WinHeight;
         glViewport(0, 0, wt->WinWidth, wt->WinHeight);
         glMatrixMode(GL_PROJECTION);
         glLoadIdentity();
         glFrustum(-w, w, -1.0, 1.0, 1.5, 10);
         glMatrixMode(GL_MODELVIEW);
         glLoadIdentity();
         glTranslatef(0, 0, -2.5);
         wt->NewSize = GL_FALSE;
      }

      if (wt->MakeNewTexture) {
         MakeNewTexture(wt);
         wt->MakeNewTexture = GL_FALSE;
      }

      glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

      glPushMatrix();
         glRotatef(wt->Angle, 0, 1, 0);
         glRotatef(wt->Angle, 1, 0, 0);
         glScalef(0.7, 0.7, 0.7);
         draw_object();
      glPopMatrix();

      LOCK(wt->Dpy);

      glXSwapBuffers(wt->Dpy, wt->Win);

      UNLOCK(wt->Dpy);

      if (Animate) {
         usleep(5000);
      }
      else {
         /* wait for signal to draw */
         pthread_mutex_lock(&CondMutex);
         pthread_cond_wait(&CondVar, &CondMutex);
         pthread_mutex_unlock(&CondMutex);
      }
      wt->Angle += 1.0;
   }
}


static void
keypress(XEvent *event, struct winthread *wt)
{
   char buf[100];
   KeySym keySym;
   XComposeStatus stat;

   XLookupString(&event->xkey, buf, sizeof(buf), &keySym, &stat);

   switch (keySym) {
   case XK_Escape:
      /* tell all threads to exit */
      if (!Animate) {
         signal_redraw();
      }
      ExitFlag = GL_TRUE;
      /*printf("exit draw_loop %d\n", wt->Index);*/
      return;
   case XK_t:
   case XK_T:
      if (Texture) {
         wt->MakeNewTexture = GL_TRUE;
         if (!Animate)
            signal_redraw();
      }
      break;
   case XK_a:
   case XK_A:
      Animate = !Animate;
      if (Animate)  /* yes, prev Animate state! */
         signal_redraw();
      break;
   case XK_s:
   case XK_S:
      if (!Animate)
         signal_redraw();
      break;
   default:
      ; /* nop */
   }
}


/*
 * The main process thread runs this loop.
 * Single display connection for all threads.
 */
static void
event_loop(Display *dpy)
{
   XEvent event;
   int i;

   assert(!MultiDisplays);

   while (!ExitFlag) {

      while (1) {
         int k;
         LOCK(dpy);
         k = XPending(dpy);
         if (k) {
            XNextEvent(dpy, &event);
            UNLOCK(dpy);
            break;
         }
         UNLOCK(dpy);
         usleep(5000);
      }

      switch (event.type) {
         case ConfigureNotify:
            /* Find winthread for this event's window */
            for (i = 0; i < NumWinThreads; i++) {
               struct winthread *wt = &WinThreads[i];
               if (event.xconfigure.window == wt->Win) {
                  resize(wt, event.xconfigure.width,
                         event.xconfigure.height);
                  break;
               }
            }
            break;
         case KeyPress:
            for (i = 0; i < NumWinThreads; i++) {
               struct winthread *wt = &WinThreads[i];
               if (event.xkey.window == wt->Win) {
                  keypress(&event, wt);
                  break;
               }
            }
            break;
         default:
            /*no-op*/ ;
      }
   }
}


/*
 * Separate display connection for each thread.
 */
static void
event_loop_multi(void)
{
   XEvent event;
   int w = 0;

   assert(MultiDisplays);

   while (!ExitFlag) {
      struct winthread *wt = &WinThreads[w];
      if (XPending(wt->Dpy)) {
         XNextEvent(wt->Dpy, &event);
         switch (event.type) {
         case ConfigureNotify:
            resize(wt, event.xconfigure.width, event.xconfigure.height);
            break;
         case KeyPress:
            keypress(&event, wt);
            break;
         default:
            ; /* nop */
         }
      }
      w = (w + 1) % NumWinThreads;
      usleep(5000);
   }
}



/*
 * we'll call this once for each thread, before the threads are created.
 */
static void
create_window(struct winthread *wt, GLXContext shareCtx)
{
   Window win;
   GLXContext ctx;
   int attrib[] = { GLX_RGBA,
                    GLX_RED_SIZE, 1,
                    GLX_GREEN_SIZE, 1,
                    GLX_BLUE_SIZE, 1,
                    GLX_DEPTH_SIZE, 1,
                    GLX_DOUBLEBUFFER,
                    None };
   int scrnum;
   XSetWindowAttributes attr;
   unsigned long mask;
   Window root;
   XVisualInfo *visinfo;
   int width = 160, height = 160;
   int xpos = (wt->Index % 8) * (width + 10);
   int ypos = (wt->Index / 8) * (width + 20);

   scrnum = DefaultScreen(wt->Dpy);
   root = RootWindow(wt->Dpy, scrnum);

   visinfo = glXChooseVisual(wt->Dpy, scrnum, attrib);
   if (!visinfo) {
      Error("Unable to find RGB, Z, double-buffered visual");
   }

   /* window attributes */
   attr.background_pixel = 0;
   attr.border_pixel = 0;
   attr.colormap = XCreateColormap(wt->Dpy, root, visinfo->visual, AllocNone);
   attr.event_mask = StructureNotifyMask | ExposureMask | KeyPressMask;
   mask = CWBackPixel | CWBorderPixel | CWColormap | CWEventMask;

   win = XCreateWindow(wt->Dpy, root, xpos, ypos, width, height,
                        0, visinfo->depth, InputOutput,
                        visinfo->visual, mask, &attr);
   if (!win) {
      Error("Couldn't create window");
   }

   {
      XSizeHints sizehints;
      sizehints.x = xpos;
      sizehints.y = ypos;
      sizehints.width  = width;
      sizehints.height = height;
      sizehints.flags = USSize | USPosition;
      XSetNormalHints(wt->Dpy, win, &sizehints);
      XSetStandardProperties(wt->Dpy, win, "glthreads", "glthreads",
                              None, (char **)NULL, 0, &sizehints);
   }


   ctx = glXCreateContext(wt->Dpy, visinfo, shareCtx, True);
   if (!ctx) {
      Error("Couldn't create GLX context");
   }

   XMapWindow(wt->Dpy, win);
   XSync(wt->Dpy, 0);

   /* save the info for this window/context */
   wt->Win = win;
   wt->Context = ctx;
   wt->Angle = 0.0;
   wt->WinWidth = width;
   wt->WinHeight = height;
   wt->NewSize = GL_TRUE;
}


/*
 * Called by pthread_create()
 */
static void *
thread_function(void *p)
{
   struct winthread *wt = (struct winthread *) p;
   draw_loop(wt);
   return NULL;
}


/*
 * called before exit to wait for all threads to finish
 */
static void
clean_up(void)
{
   int i;

   /* wait for threads to finish */
   for (i = 0; i < NumWinThreads; i++) {
      pthread_join(WinThreads[i].Thread, NULL);
   }

   for (i = 0; i < NumWinThreads; i++) {
      glXDestroyContext(WinThreads[i].Dpy, WinThreads[i].Context);
      XDestroyWindow(WinThreads[i].Dpy, WinThreads[i].Win);
   }
}


static void
usage(void)
{
   printf("glthreads: test of GL thread safety (any key = exit)\n");
   printf("Usage:\n");
   printf("  glthreads [options]\n");
   printf("Options:\n");
   printf("   -display DISPLAYNAME  Specify display string\n");
   printf("   -n NUMTHREADS  Number of threads to create\n");
   printf("   -p  Use a separate display connection for each thread\n");
   printf("   -l  Use application-side locking\n");
   printf("   -t  Enable texturing\n");
   printf("Keyboard:\n");
   printf("   Esc  Exit\n");
   printf("   t    Change texture image (requires -t option)\n");
   printf("   a    Toggle animation\n");
   printf("   s    Step rotation (when not animating)\n");
}


int
main(int argc, char *argv[])
{
   char *displayName = NULL;
   int numThreads = 2;
   Display *dpy = NULL;
   int i;
   Status threadStat;

   if (argc == 1) {
      usage();
   }
   else {
      for (i = 1; i < argc; i++) {
         if (strcmp(argv[i], "-display") == 0 && i + 1 < argc) {
            displayName = argv[i + 1];
            i++;
         }
         else if (strcmp(argv[i], "-p") == 0) {
            MultiDisplays = 1;
         }
         else if (strcmp(argv[i], "-l") == 0) {
            Locking = 1;
         }
         else if (strcmp(argv[i], "-t") == 0) {
            Texture = 1;
         }
         else if (strcmp(argv[i], "-n") == 0 && i + 1 < argc) {
            numThreads = atoi(argv[i + 1]);
            if (numThreads < 1)
               numThreads = 1;
            else if (numThreads > MAX_WINTHREADS)
               numThreads = MAX_WINTHREADS;
            i++;
         }
         else {
            usage();
            exit(1);
         }
      }
   }

   if (Locking)
      printf("glthreads: Using explicit locks around Xlib calls.\n");
   else if (!MultiDisplays)
      printf("glthreads: Using XLockDisplay()/XUnlockDisplay().\n");

   if (MultiDisplays)
      printf("glthreads: Per-thread display connections.\n");
   else
      printf("glthreads: Single display connection.\n");

   /*
    * VERY IMPORTANT: call XInitThreads() before any other Xlib functions.
    */
   if (!MultiDisplays) {
      if (!Locking) {
         threadStat = XInitThreads();
      if (threadStat) {
         printf("XInitThreads() returned %d (success)\n", (int) threadStat);
      }
      else {
         printf("XInitThreads() returned 0 (failure- this program may fail)\n");
      }
      }

      dpy = XOpenDisplay(displayName);
      if (!dpy) {
         fprintf(stderr, "Unable to open display %s\n", XDisplayName(displayName));
         return -1;
      }
   }

   pthread_mutex_init(&Mutex, NULL);
   pthread_mutex_init(&CondMutex, NULL);
   pthread_cond_init(&CondVar, NULL);

   printf("glthreads: creating windows\n");

   NumWinThreads = numThreads;

   /* Create the GLX windows and contexts */
   for (i = 0; i < numThreads; i++) {
      GLXContext share;

      if (MultiDisplays) {
         WinThreads[i].Dpy = XOpenDisplay(displayName);
         assert(WinThreads[i].Dpy);
      }
      else {
         WinThreads[i].Dpy = dpy;
      }
      WinThreads[i].Index = i;
      WinThreads[i].Initialized = GL_FALSE;

      share = (Texture && i > 0) ? WinThreads[0].Context : 0;

      create_window(&WinThreads[i], share);
   }

   printf("glthreads: creating threads\n");

   /* Create the threads */
   for (i = 0; i < numThreads; i++) {
      pthread_create(&WinThreads[i].Thread, NULL, thread_function,
                     (void*) &WinThreads[i]);
      printf("glthreads: Created thread %p\n",
             (void *) (size_t) WinThreads[i].Thread);
   }

   if (MultiDisplays)
      event_loop_multi();
   else
      event_loop(dpy);

   clean_up();

   if (MultiDisplays) {
      for (i = 0; i < numThreads; i++) {
         XCloseDisplay(WinThreads[i].Dpy);
      }
   }
   else {
      XCloseDisplay(dpy);
   }

   return 0;
}
