//
// ********************************************************************
// * License and Disclaimer                                           *
// *                                                                  *
// * The  Geant4 software  is  copyright of the Copyright Holders  of *
// * the Geant4 Collaboration.  It is provided  under  the terms  and *
// * conditions of the Geant4 Software License,  included in the file *
// * LICENSE and available at  http://cern.ch/geant4/license .  These *
// * include a list of copyright holders.                             *
// *                                                                  *
// * Neither the authors of this software system, nor their employing *
// * institutes,nor the agencies providing financial support for this *
// * work  make  any representation or  warranty, express or implied, *
// * regarding  this  software system or assume any liability for its *
// * use.  Please see the license in the file  LICENSE  and URL above *
// * for the full disclaimer and the limitation of liability.         *
// *                                                                  *
// * This  code  implementation is the result of  the  scientific and *
// * technical work of the GEANT4 collaboration.                      *
// * By using,  copying,  modifying or  distributing the software (or *
// * any work based  on the software)  you  agree  to acknowledge its *
// * use  in  resulting  scientific  publications,  and indicate your *
// * acceptance of all terms of the Geant4 Software license.          *
// ********************************************************************
//
//
// $Id: G4OpenGLXViewer.cc,v 1.34 2006/11/01 11:22:26 allison Exp $
// GEANT4 tag $Name: geant4-08-02-patch-01 $
//
// 
// Andrew Walkden  7th February 1997
// G4OpenGLXViewer : Class to provide XWindows specific
//                 functionality for OpenGL in GEANT4

#ifdef G4VIS_BUILD_OPENGLX_DRIVER

#include "G4OpenGLXViewer.hh"

#include "G4OpenGLFontBaseStore.hh"

#include <sstream>

#include "G4VisExtent.hh"
#include "G4LogicalVolume.hh"
#include "G4VSolid.hh"
#include "G4Point3D.hh"
#include "G4Normal3D.hh"

#include <X11/Xatom.h>
#include <X11/Xutil.h>

#include <assert.h>

int G4OpenGLXViewer::snglBuf_RGBA[12] =
{ GLX_RGBA,
  GLX_RED_SIZE, 1,
  GLX_GREEN_SIZE, 1, 
  GLX_BLUE_SIZE, 1,
  GLX_DEPTH_SIZE, 1,
  GLX_STENCIL_SIZE, 1,
  None };

int G4OpenGLXViewer::dblBuf_RGBA[13] =
{ GLX_RGBA,
  GLX_RED_SIZE, 1,
  GLX_GREEN_SIZE, 1,
  GLX_BLUE_SIZE, 1,
  GLX_DOUBLEBUFFER,
  GLX_DEPTH_SIZE, 1,
  GLX_STENCIL_SIZE, 1,
  None };

#define NewString(str) \
 ((str) != NULL ? (strcpy((char*)malloc((unsigned)strlen(str) + 1), str)) : (char*)NULL)

#define USE_DEFAULT_COLORMAP 1
#define USE_STANDARD_COLORMAP 0

static const char* gouraudtriangleEPS[] =
{
  "/bd{bind def}bind def /triangle { aload pop   setrgbcolor  aload pop 5 3",
  "roll 4 2 roll 3 2 roll exch moveto lineto lineto closepath fill } bd",
  "/computediff1 { 2 copy sub abs threshold ge {pop pop pop true} { exch 2",
  "index sub abs threshold ge { pop pop true} { sub abs threshold ge } ifelse",
  "} ifelse } bd /computediff3 { 3 copy 0 get 3 1 roll 0 get 3 1 roll 0 get",
  "computediff1 {true} { 3 copy 1 get 3 1 roll 1 get 3 1 roll 1 get",
  "computediff1 {true} { 3 copy 2 get 3 1 roll  2 get 3 1 roll 2 get",
  "computediff1 } ifelse } ifelse } bd /middlecolor { aload pop 4 -1 roll",
  "aload pop 4 -1 roll add 2 div 5 1 roll 3 -1 roll add 2 div 3 1 roll add 2",
  "div 3 1 roll exch 3 array astore } bd /gouraudtriangle { computediff3 { 4",
  "-1 roll aload 7 1 roll 6 -1 roll pop 3 -1 roll pop add 2 div 3 1 roll add",
  "2 div exch 3 -1 roll aload 7 1 roll exch pop 4 -1 roll pop add 2 div 3 1",
  "roll add 2 div exch 3 -1 roll aload 7 1 roll pop 3 -1 roll pop add 2 div 3",
  "1 roll add 2 div exch 7 3 roll 10 -3 roll dup 3 index middlecolor 4 1 roll",
  "2 copy middlecolor 4 1 roll 3 copy pop middlecolor 4 1 roll 13 -1 roll",
  "aload pop 17 index 6 index 15 index 19 index 6 index 17 index 6 array",
  "astore 10 index 10 index 14 index gouraudtriangle 17 index 5 index 17",
  "index 19 index 5 index 19 index 6 array astore 10 index 9 index 13 index",
  "gouraudtriangle 13 index 16 index 5 index 15 index 18 index 5 index 6",
  "array astore 12 index 12 index 9 index gouraudtriangle 17 index 16 index",
  "15 index 19 index 18 index 17 index 6 array astore 10 index 12 index 14",
  "index gouraudtriangle 18 {pop} repeat } { aload pop 5 3 roll aload pop 7 3",
  "roll aload pop 9 3 roll 4 index 6 index 4 index add add 3 div 10 1 roll 7",
  "index 5 index 3 index add add 3 div 10 1 roll 6 index 4 index 2 index add",
  "add 3 div 10 1 roll 9 {pop} repeat 3 array astore triangle } ifelse } bd",
  NULL
};

XVisualInfo*  G4OpenGLXViewer::vi_single_buffer = 0;
XVisualInfo*  G4OpenGLXViewer::vi_double_buffer = 0;

extern "C" {
  Bool G4OpenGLXViewerWaitForNotify (Display*, XEvent* e, char* arg) {
    return (e->type == MapNotify) && (e->xmap.window == (Window) arg);
  }
}

void G4OpenGLXViewer::SetView () {
  glXMakeCurrent (dpy, win, cx);
  G4OpenGLViewer::SetView ();  
}

void G4OpenGLXViewer::ShowView () {
  glXWaitGL (); //Wait for effects of all previous OpenGL commands to
                //be propagated before progressing.
  glFlush ();
}

void G4OpenGLXViewer::GetXConnection () {
// get a connection.
  dpy = XOpenDisplay (0);
  if (!dpy) {
    fViewId = -1;  // This flags an error.
    G4cerr << "G4OpenGLViewer::G4OpenGLViewer couldn't open display." << G4endl;
    return;
  }

// make sure OpenGL is supported and installed properly.
  if (!glXQueryExtension (dpy, &errorBase, &eventBase)) {
    fViewId = -1;  // This flags an error.
    G4cerr << "G4OpenGLViewer::G4OpenGLViewer X Server has no GLX extension." 
	 << G4endl;
    return;
  }

}

void G4OpenGLXViewer::CreateGLXContext (XVisualInfo* v) {

  vi = v;
// get window's attributes
  if (!XGetWindowAttributes(dpy, XRootWindow (dpy, vi -> screen), &xwa)) {
    fViewId = -1;  // This flags an error.
    G4cerr << "G4OpenGLViewer::G4OpenGLViewer couldn't return window attributes"
	 << G4endl;
    return;
  }
  
// create a GLX context
  cx = glXCreateContext (dpy, vi, 0, true);
  if (!cx) {
    fViewId = -1;  // This flags an error.
    G4cerr << "G4OpenGLViewer::G4OpenGLViewer couldn't create context."
	 << G4endl;
    return;
  }

// New stab at getting a colormap

  Status status;
  XStandardColormap *standardCmaps = XAllocStandardColormap ();
  int i, numCmaps;

  status = XmuLookupStandardColormap (dpy, 
				      vi -> screen, 
				      vi -> visualid, 
				      vi -> depth, 
				      XA_RGB_DEFAULT_MAP, 
				      False, 
				      True);
  
  if (status == 1) {
    status = XGetRGBColormaps (dpy, 
			       XRootWindow (dpy, vi -> screen), 
			       &standardCmaps, 
			       &numCmaps, 
			       XA_RGB_DEFAULT_MAP);
    if (status == 1)
      for (i = 0; i < numCmaps; i++)
	if (standardCmaps[i].visualid == vi -> visualid) {
	  cmap = standardCmaps[i].colormap;
	  XFree (standardCmaps);
	}
    G4cout << "Got standard cmap" << G4endl;
  } else {
    cmap = XCreateColormap (dpy, 
			    XRootWindow(dpy, vi -> screen), 
			    vi -> visual, 
			    AllocNone);
    G4cout << "Created own cmap" << G4endl;
  }

  if (!cmap) {
    fViewId = -1;  // This flags an error.
    G4cerr << "G4OpenGLViewer::G4OpenGLViewer failed to allocate a Colormap."
	 << G4endl;
    return;
  }

}
  
void G4OpenGLXViewer::CreateMainWindow () {
  
// create a window
  swa.colormap = cmap;
  swa.border_pixel = 0;
  swa.event_mask = ExposureMask | ButtonPressMask | StructureNotifyMask;
  swa.backing_store = WhenMapped;

  // Window size and position...
  unsigned int width, height;
  x_origin = 0;
  y_origin = 0;
  size_hints = XAllocSizeHints();
  const G4String& XGeometryString = fVP.GetXGeometryString();
  int screen_num = DefaultScreen(dpy);
  if (!XGeometryString.empty()) {
    G4int geometryResultMask = XParseGeometry
      ((char*)XGeometryString.c_str(),
       &x_origin, &y_origin, &width, &height);
    if (geometryResultMask & (WidthValue | HeightValue)) {
      if (geometryResultMask & XValue) {
	if (geometryResultMask & XNegative) {
	  x_origin = DisplayWidth(dpy, screen_num) + x_origin - width;
	}
	size_hints->flags |= PPosition;
	size_hints->x = x_origin;
      }
      if (geometryResultMask & YValue) {
	if (geometryResultMask & YNegative) {
	  y_origin = DisplayHeight(dpy, screen_num) + y_origin - height;
	}
	size_hints->flags |= PPosition;
	size_hints->y = y_origin;
      }
    } else {
      G4cout << "ERROR: Geometry string \""
	     << XGeometryString
	     << "\" invalid.  Using \"600x600\"."
	     << G4endl;
      width = 600;
      height = 600;
    }
  }
  size_hints->width = width;
  size_hints->height = height;
  size_hints->flags |= PSize;

  //  G4int                             WinSize_x;
  //  G4int                             WinSize_y;
  WinSize_x = width;
  WinSize_y = height;

  G4cout << "Window name: " << fName << G4endl;
  strncpy (charViewName, fName, 100);
  char *window_name = charViewName;
  char *icon_name = charViewName;
  //char tmpatom[] = "XA_WM_NORMAL_HINTS"; 
  wm_hints = XAllocWMHints();
  class_hints = XAllocClassHint();

  XStringListToTextProperty (&window_name, 1, &windowName);
  XStringListToTextProperty (&icon_name, 1, &iconName);

  wm_hints -> initial_state = NormalState;
  wm_hints -> input = True;
  wm_hints -> icon_pixmap = icon_pixmap;
  wm_hints -> flags = StateHint | IconPixmapHint | InputHint;

  class_hints -> res_name  = NewString("G4OpenGL");
  class_hints -> res_class = NewString("G4OpenGL");

  win = XCreateWindow (dpy, XRootWindow (dpy, vi -> screen), x_origin, 
                       y_origin, WinSize_x, WinSize_y, 0, vi -> depth,
                       InputOutput, vi -> visual,  
                       CWBorderPixel | CWColormap | 
                       CWEventMask | CWBackingStore,
                       &swa);
  
  XSetWMProperties (dpy, win, &windowName, &iconName, 0, 0, 
                    size_hints, wm_hints, class_hints);
  
// request X to Draw window on screen.
  XMapWindow (dpy, win);

// Wait for window to appear (wait for an "expose" event).
  XIfEvent (dpy, &event, G4OpenGLXViewerWaitForNotify, (char*) win);

// connect the context to a window
  glXMakeCurrent (dpy, win, cx);

}

void G4OpenGLXViewer::CreateFontLists () {

  std::map<G4double,G4String> fonts;  // G4VMarker screen size and font name.
  fonts[10.] = "-adobe-courier-bold-r-normal--10-100-75-75-m-60-iso8859-1";
  fonts[11.] = "-adobe-courier-bold-r-normal--11-80-100-100-m-60-iso8859-1";
  fonts[12.] = "-adobe-courier-bold-r-normal--12-120-75-75-m-70-iso8859-1";
  fonts[13.] = "fixed";
  fonts[14.] = "-adobe-courier-bold-r-normal--14-100-100-100-m-90-iso8859-1";
  fonts[17.] = "-adobe-courier-bold-r-normal--17-120-100-100-m-100-iso8859-1";
  fonts[18.] = "-adobe-courier-bold-r-normal--18-180-75-75-m-110-iso8859-1";
  fonts[20.] = "-adobe-courier-bold-r-normal--20-140-100-100-m-110-iso8859-1";
  fonts[24.] = "-adobe-courier-bold-r-normal--24-240-75-75-m-150-iso8859-1";
  fonts[25.] = "-adobe-courier-bold-r-normal--25-180-100-100-m-150-iso8859-1";
  fonts[34.] = "-adobe-courier-bold-r-normal--34-240-100-100-m-200-iso8859-1";
  std::map<G4double,G4String>::const_iterator i;
  for (i = fonts.begin(); i != fonts.end(); ++i) {
    XFontStruct* font_info = XLoadQueryFont(dpy, i->second);
    if (!font_info) {
      G4cerr <<
	"G4OpenGLXViewer: XLoadQueryFont failed for font\n  "
	     << i->second
	     << G4endl;
      continue;
    }
    G4int font_base = glGenLists(256);
    if (!font_base) {
      G4cerr << "G4OpenGLXViewer: out of display lists for fonts." 
	     << G4endl;
      continue;
    }
    G4int first = font_info->min_char_or_byte2;
    G4int last  = font_info->max_char_or_byte2;
    glXUseXFont(font_info->fid, first, last-first+1,font_base+first);
    G4OpenGLFontBaseStore::AddFontBase(this,font_base,i->first,i->second);
  }
}

G4OpenGLXViewer::G4OpenGLXViewer (G4OpenGLSceneHandler& scene):
G4VViewer (scene, -1),
G4OpenGLViewer (scene),
print_colour (true),
vectored_ps (true),
vi_immediate (0),
vi_stored (0)
{

  strcpy (print_string, "G4OpenGL.eps");

  GetXConnection ();
  if (fViewId < 0) return;
  
  // Try for a visual suitable for OpenGLImmediate..
  // first try for a single buffered RGB window
  if (!vi_single_buffer) {
    vi_single_buffer =
      glXChooseVisual (dpy, XDefaultScreen (dpy), snglBuf_RGBA);
  }
  if (!vi_double_buffer) {
    vi_double_buffer =
      glXChooseVisual (dpy, XDefaultScreen (dpy), dblBuf_RGBA);
  }

  if (vi_single_buffer || vi_double_buffer) {
    if (!vi_double_buffer) {
      G4cout <<
	"G4OpenGLXViewer::G4OpenGLXViewer: unable to get a double buffer visual."
	"\n  Working with a single buffer."
	     << G4endl;
    }
  } else {
    if (!vi_single_buffer) {
      G4cout <<
	"G4OpenGLXViewer::G4OpenGLXViewer: unable to get a single buffer visual."
	     << G4endl;
    }
    if (!vi_double_buffer) {
      G4cout <<
	"G4OpenGLXViewer::G4OpenGLXViewer: unable to get a double buffer visual."
	     << G4endl;
    }
  }

  if (vi_single_buffer) {
    vi_immediate = vi_single_buffer;
    attributeList = snglBuf_RGBA;
  }
  
  if (!vi_immediate){
    // next try for a double buffered RGB, but Draw to top buffer
    if (vi_double_buffer) {
      vi_immediate = vi_double_buffer;
      attributeList = dblBuf_RGBA;
    }
  }

  // Now try for a visual suitable for OpenGLStored...
  // Try for a double buffered RGB window
  if (vi_double_buffer) {
    vi_stored = vi_double_buffer;
    attributeList = dblBuf_RGBA;
  }

  if (!vi_immediate || !vi_stored) {
    G4cout <<
    "G4OpenGLXViewer::G4OpenGLXViewer: unable to get required visuals."
	   << G4endl;
    fViewId = -1;  // This flags an error.
  }

  //  glClearColor (0., 0., 0., 0.);
  //  glClearDepth (1.);
}

G4OpenGLXViewer::~G4OpenGLXViewer () {
  if (fViewId >= 0) {
    //Close a window from here
    glXMakeCurrent (dpy, None, NULL);
    glXDestroyContext (dpy, cx);
    if (win) XDestroyWindow (dpy, win); // ...if already deleted in
    // sub-class G4OpenGLXmViewer.
    XFlush (dpy);
  }
}

void G4OpenGLXViewer::print() {
  
  //using namespace std;
  //cout << "print_col_callback requested with file name: " << print_string << G4endl;
  
  if (vectored_ps) {
    G4int size = 5000000;
    
    GLfloat* feedback_buffer;
    GLint returned;
    FILE* file;
    
    feedback_buffer = new GLfloat[size];
    glFeedbackBuffer (size, GL_3D_COLOR, feedback_buffer);
    glRenderMode (GL_FEEDBACK);
    
    DrawView();
    returned = glRenderMode (GL_RENDER);
    
    if (print_string) {
      file = fopen (print_string, "w");
      if (file) {
	spewWireframeEPS (file, returned, feedback_buffer, "rendereps");
      } else {
	printf("Could not open %s\n", print_string);
      }
    } else {
      printBuffer (returned, feedback_buffer);
    }
    //  free (feedback_buffer);
    delete[] feedback_buffer;

  } else {

    XVisualInfo* pvi;
    GLXContext pcx = create_GL_print_context(pvi);
    GLXContext tmp_cx;
    tmp_cx = cx;
    cx=pcx;
    
    Pixmap pmap = XCreatePixmap (dpy,
				 XRootWindow (dpy, pvi->screen),
				 WinSize_x, WinSize_y,
				 pvi->depth);
    
    GLXPixmap glxpmap = glXCreateGLXPixmap (dpy, 
					    pvi,
					    pmap);
    
    GLXDrawable tmp_win;
    tmp_win=win;
    win=glxpmap;
    
    glXMakeCurrent (dpy,
		    glxpmap,
		    cx);
    
    glViewport (0, 0, WinSize_x, WinSize_y);
    
    ClearView ();
    DrawView ();
    
    generateEPS (print_string,
		 print_colour,
		 WinSize_x, WinSize_y);
    
    win=tmp_win;
    cx=tmp_cx;
    
    glXMakeCurrent (dpy,
		    glxpmap,
		    cx);
    
  }

}

void G4OpenGLXViewer::print3DcolorVertex(GLint size, GLint * count, GLfloat * buffer)
{
  G4int i;

  printf("  ");
  for (i = 0; i < 7; i++) {
    printf("%4.2f ", buffer[size - (*count)]);
    *count = *count - 1;
  }
  printf("\n");
}

void G4OpenGLXViewer::spewWireframeEPS (FILE* file, GLint size, GLfloat* buffer, const char* cr) {

  GLfloat EPS_GOURAUD_THRESHOLD=0.1;

  GLfloat clearColor[4], viewport[4];
  GLfloat lineWidth;
  G4int i;

  glGetFloatv (GL_VIEWPORT, viewport);
  glGetFloatv (GL_COLOR_CLEAR_VALUE, clearColor);
  glGetFloatv (GL_LINE_WIDTH, &lineWidth);
  glGetFloatv (GL_POINT_SIZE, &pointSize);

  fputs ("%!PS-Adobe-2.0 EPSF-2.0\n", file);
  fprintf (file, "%%%%Creator: %s (using OpenGL feedback)\n", cr);
  fprintf (file, "%%%%BoundingBox: %g %g %g %g\n", viewport[0], viewport[1], viewport[2], viewport[3]);
  fputs ("%%EndComments\n", file);
  fputs ("\n", file);
  fputs ("gsave\n", file);
  fputs ("\n", file);

  fputs ("% the gouraudtriangle PostScript fragment below is free\n", file);
  fputs ("% written by Frederic Delhoume (delhoume@ilog.fr)\n", file);
  fprintf (file, "/threshold %g def\n", EPS_GOURAUD_THRESHOLD);
  for (i=0; gouraudtriangleEPS[i]; i++) {
    fprintf (file, "%s\n", gouraudtriangleEPS[i]);
  }

  fprintf(file, "\n%g setlinewidth\n", lineWidth);
  
  fprintf (file, "%g %g %g setrgbcolor\n", clearColor[0], clearColor[1], clearColor[2]);
  fprintf (file, "%g %g %g %g rectfill\n\n", viewport[0], viewport[1], viewport[2], viewport[3]);

  spewSortedFeedback (file, size, buffer);

  fputs ("grestore\n\n", file);
  fputs ("showpage\n", file);

  fclose(file);
}

void G4OpenGLXViewer::printBuffer (GLint size, GLfloat* buffer) {

  GLint count;
  G4int token, nvertices;

  count=size;
  while(count) {
    token=G4int (buffer[size-count]);
    count--;
    switch (token) {

    case GL_PASS_THROUGH_TOKEN:
      printf ("GL_PASS_THROUGH_TOKEN\n");
      printf ("  %4.2f\n", buffer[size-count]);
      count--;
      break;

    case GL_POINT_TOKEN:
      printf ("GL_POINT_TOKEN\n");
      print3DcolorVertex (size, &count, buffer);
      break;

    case GL_LINE_TOKEN:
      printf ("GL_LINE_TOKEN\n");
      print3DcolorVertex (size, &count, buffer);
      print3DcolorVertex (size, &count, buffer);
      break;
      
    case GL_LINE_RESET_TOKEN:
      printf ("GL_LINE_RESET_TOKEN\n");
      print3DcolorVertex (size, &count, buffer);
      print3DcolorVertex (size, &count, buffer);
      break;

    case GL_POLYGON_TOKEN:
      printf ("GL_POLYGON_TOKEN\n");
      nvertices=G4int (buffer[size-count]);
      count--;
      for (; nvertices>0; nvertices--) {
	print3DcolorVertex (size, &count, buffer);
      }
    }
  }
}

G4float* G4OpenGLXViewer::spewPrimitiveEPS (FILE* file, GLfloat* loc) {
  
  G4int token;
  G4int nvertices, i;
  GLfloat red, green, blue, intensity;
  G4int smooth;
  GLfloat dx, dy, dr, dg, db, absR, absG, absB, colormax;
  G4int steps;
  Feedback3Dcolor *vertex;
  GLfloat xstep(0.), ystep(0.), rstep(0.), gstep(0.), bstep(0.);
  GLfloat xnext(0.), ynext(0.), rnext(0.), gnext(0.), bnext(0.), distance(0.);

  token=G4int (*loc);
  loc++;
  switch (token) {
  case GL_LINE_RESET_TOKEN:
  case GL_LINE_TOKEN:
    vertex=(Feedback3Dcolor*)loc;
    dr=vertex[1].red - vertex[0].red;
    dg=vertex[1].green - vertex[0].green;
    db=vertex[1].blue - vertex[0].blue;

    if (!print_colour) {
      dr+=(dg+db);
      dr/=3.0;
      dg=dr;
      db=dr;
    }

    if (dr!=0 || dg!=0 || db!=0) {
      dx=vertex[1].x - vertex[0].x;
      dy=vertex[1].y - vertex[0].y;
      distance=std::sqrt(dx*dx + dy*dy);

      absR=std::fabs(dr);
      absG=std::fabs(dg);
      absB=std::fabs(db);

      #define Max(a, b) (((a)>(b))?(a):(b))

      #define EPS_SMOOTH_LINE_FACTOR 0.06

      colormax=Max(absR, Max(absG, absB));
      steps=Max(1, G4int (colormax*distance*EPS_SMOOTH_LINE_FACTOR));
      
      xstep=dx/steps;
      ystep=dy/steps;

      rstep=dr/steps;
      gstep=dg/steps;
      bstep=db/steps;

      xnext=vertex[0].x;
      ynext=vertex[0].y;
      rnext=vertex[0].red;
      gnext=vertex[0].green;
      bnext=vertex[0].blue;

      if (!print_colour) {
	rnext+=(gnext+bnext);
	rnext/=3.0;
	gnext=rnext;
	bnext=rnext;
      }

      xnext -= xstep/2.0;
      ynext -= ystep/2.0;
      rnext -= rstep/2.0;
      gnext -= gstep/2.0;
      bnext -= bstep/2.0;
    } else {
      steps=0;
    }
    if (print_colour) {
      fprintf (file, "%g %g %g setrgbcolor\n",
	       vertex[0].red, vertex[0].green, vertex[0].blue);
    } else {
      intensity = (vertex[0].red + vertex[0].green + vertex[0].blue) / 3.0;
      fprintf (file, "%g %g %g setrgbcolor\n",
	       intensity, intensity, intensity);
    }      
    fprintf (file, "%g %g moveto\n", vertex[0].x, vertex[0].y);

    for (i=0; i<steps; i++) {

      xnext += xstep;
      ynext += ystep;
      rnext += rstep;
      gnext += gstep;
      bnext += bstep;

      fprintf (file, "%g %g lineto stroke\n", xnext, ynext);
      fprintf (file, "%g %g %g setrgbcolor\n", rnext, gnext, bnext);
      fprintf (file, "%g %g moveto\n", xnext, ynext);
    }
    fprintf (file, "%g %g lineto stroke\n", vertex[1].x, vertex[1].y);

    loc += 14;
    break;

  case GL_POLYGON_TOKEN:
    nvertices = G4int (*loc);
    loc++;
    vertex=(Feedback3Dcolor*)loc;
    if (nvertices>0) {
      red=vertex[0].red;
      green=vertex[0].green;
      blue=vertex[0].blue;
      smooth=0;
      
      if (!print_colour) {
	red+=(green+blue);
	red/=3.0;
	green=red;
	blue=red;
      }
      
      if (print_colour) {
	for (i=1; i<nvertices; i++) {
	  if (red!=vertex[i].red || green!=vertex[i].green || blue!=vertex[i].blue) {
	    smooth=1;
	    break;
	  }
	}
      } else {
	for (i=1; i<nvertices; i++) {
	  intensity = vertex[i].red + vertex[i].green + vertex[i].blue;
	  intensity/=3.0;
	  if (red!=intensity) {
	    smooth=1;
	    break;
	  }
	}
      }

      if (smooth) {
	G4int triOffset;
	for (i=0; i<nvertices-2; i++) {
	  triOffset = i*7;
	  fprintf (file, "[%g %g %g %g %g %g]",
		   vertex[0].x, vertex[i+1].x, vertex[i+2].x,
		   vertex[0].y, vertex[i+1].y, vertex[i+2].y);
	  if (print_colour) {
	    fprintf (file, " [%g %g %g] [%g %g %g] [%g %g %g] gouraudtriangle\n",
		     vertex[0].red, vertex[0].green, vertex[0].blue,
		     vertex[i+1].red, vertex[i+1].green, vertex[i+1].blue,
		     vertex[i+2].red, vertex[i+2].green, vertex[i+2].blue);
	  } else {

	    intensity = vertex[0].red + vertex[0].green + vertex[0].blue;
	    intensity/=3.0;
	    fprintf (file, " [%g %g %g]", intensity, intensity, intensity);

	    intensity = vertex[1].red + vertex[1].green + vertex[1].blue;
	    intensity/=3.0;
	    fprintf (file, " [%g %g %g]", intensity, intensity, intensity);

	    intensity = vertex[2].red + vertex[2].green + vertex[2].blue;
	    intensity/=3.0;
	    fprintf (file, " [%g %g %g] gouraudtriangle\n", intensity, intensity, intensity);
	  }
	}
      } else {
	fprintf (file, "newpath\n");
	fprintf (file, "%g %g %g setrgbcolor\n", red, green, blue);
	fprintf (file, "%g %g moveto\n", vertex[0].x, vertex[0].y);
	for (i=1; i<nvertices; i++) {
	  fprintf (file, "%g %g lineto\n", vertex[i].x, vertex[i].y);
	}
	fprintf (file, "closepath fill\n\n");
      }
    }
    loc += nvertices*7;
    break;

  case GL_POINT_TOKEN:
    vertex=(Feedback3Dcolor*)loc;
    if (print_colour) {
      fprintf (file, "%g %g %g setrgbcolor\n", vertex[0].red, vertex[0].green, vertex[0].blue);
    } else {
      intensity = vertex[0].red + vertex[0].green + vertex[0].blue;
      intensity/=3.0;
      fprintf (file, "%g %g %g setrgbcolor\n", intensity, intensity, intensity);
    }      
    fprintf(file, "%g %g %g 0 360 arc fill\n\n", vertex[0].x, vertex[0].y, pointSize / 2.0);
    loc += 7;           /* Each vertex element in the feedback
                           buffer is 7 GLfloats. */
    break;
  default:
    /* XXX Left as an excersie to the reader. */
    static G4bool spewPrimitiveEPSWarned = false;
    if (!spewPrimitiveEPSWarned) {
      std::ostringstream oss;
      oss <<
	"Incomplete implementation.  Unexpected token (" << token << ")."
	"\n  (Seems to be caused by text.)";
      G4Exception("G4OpenGLXViewer::spewPrimitiveEPS",
		  "Unexpected token",
		  JustWarning,
		  oss.str().c_str());
      spewPrimitiveEPSWarned = true;
    }
  }
  return loc;
}

typedef struct G4OpenGLXViewerDepthIndex {
  GLfloat *ptr;
  GLfloat depth;
} DepthIndex;

extern "C" {
  int G4OpenGLXViewercompare(const void *a, const void *b)
  {
    const DepthIndex *p1 = (DepthIndex *) a;
    const DepthIndex *p2 = (DepthIndex *) b;
    GLfloat diff = p2->depth - p1->depth;
    
    if (diff > 0.0) {
      return 1;
    } else if (diff < 0.0) {
      return -1;
    } else {
      return 0;
    }
  }
}

void G4OpenGLXViewer::spewSortedFeedback(FILE * file, GLint size, GLfloat * buffer)
{
  int token;
  GLfloat *loc, *end;
  Feedback3Dcolor *vertex;
  GLfloat depthSum;
  int nprimitives, item;
  DepthIndex *prims;
  int nvertices, i;

  end = buffer + size;

  /* Count how many primitives there are. */
  nprimitives = 0;
  loc = buffer;
  while (loc < end) {
    token = int (*loc);
    loc++;
    switch (token) {
    case GL_LINE_TOKEN:
    case GL_LINE_RESET_TOKEN:
      loc += 14;
      nprimitives++;
      break;
    case GL_POLYGON_TOKEN:
      nvertices = int (*loc);
      loc++;
      loc += (7 * nvertices);
      nprimitives++;
      break;
    case GL_POINT_TOKEN:
      loc += 7;
      nprimitives++;
      break;
    default:
      /* XXX Left as an excersie to the reader. */
      static G4bool spewSortedFeedbackWarned = false;
      if (!spewSortedFeedbackWarned) {
	std::ostringstream oss;
	oss <<
	  "Incomplete implementation.  Unexpected token (" << token << ")."
	  "\n  (Seems to be caused by text.)";
	G4Exception("G4OpenGLXViewer::spewSortedFeedback",
		    "Unexpected token",
		    JustWarning,
		    oss.str().c_str());
	spewSortedFeedbackWarned = true;
      }
      nprimitives++;
    }
  }

  /* Allocate an array of pointers that will point back at
     primitives in the feedback buffer.  There will be one
     entry per primitive.  This array is also where we keep the
     primitive's average depth.  There is one entry per
     primitive  in the feedback buffer. */
  prims = (DepthIndex *) malloc(sizeof(DepthIndex) * nprimitives);

  item = 0;
  loc = buffer;
  while (loc < end) {
    prims[item].ptr = loc;  /* Save this primitive's location. */
    token = int (*loc);
    loc++;
    switch (token) {
    case GL_LINE_TOKEN:
    case GL_LINE_RESET_TOKEN:
      vertex = (Feedback3Dcolor *) loc;
      depthSum = vertex[0].z + vertex[1].z;
      prims[item].depth = depthSum / 2.0;
      loc += 14;
      break;
    case GL_POLYGON_TOKEN:
      nvertices = int (*loc);
      loc++;
      vertex = (Feedback3Dcolor *) loc;
      depthSum = vertex[0].z;
      for (i = 1; i < nvertices; i++) {
        depthSum += vertex[i].z;
      }
      prims[item].depth = depthSum / nvertices;
      loc += (7 * nvertices);
      break;
    case GL_POINT_TOKEN:
      vertex = (Feedback3Dcolor *) loc;
      prims[item].depth = vertex[0].z;
      loc += 7;
      break;
    default:
      /* XXX Left as an excersie to the reader. */
      assert(1);
    }
    item++;
  }
  assert(item == nprimitives);

  /* Sort the primitives back to front. */
  qsort(prims, nprimitives, sizeof(DepthIndex), G4OpenGLXViewercompare);

  /* Understand that sorting by a primitives average depth
     doesn't allow us to disambiguate some cases like self
     intersecting polygons.  Handling these cases would require
     breaking up the primitives.  That's too involved for this
     example.  Sorting by depth is good enough for lots of
     applications. */

  /* Emit the Encapsulated PostScript for the primitives in
     back to front order. */
  for (item = 0; item < nprimitives; item++) {
    (void) spewPrimitiveEPS(file, prims[item].ptr);
  }

  free(prims);
}

GLXContext G4OpenGLXViewer::create_GL_print_context(XVisualInfo*& pvi) {
  
  pvi = glXChooseVisual (dpy,
			 XDefaultScreen (dpy),
			 snglBuf_RGBA);

  if (!pvi) {
    pvi = glXChooseVisual (dpy,
			   XDefaultScreen (dpy),
			   dblBuf_RGBA);
  }

  return glXCreateContext (dpy,
			   pvi,
			   NULL,
			   False);
}

int G4OpenGLXViewer::generateEPS (char* filnam,
				int inColour,
				unsigned int width,
				unsigned int height) {

  FILE* fp;
  GLubyte* pixels;
  GLubyte* curpix;
  int components, pos, i;

  pixels = grabPixels (inColour, width, height);

  if (pixels == NULL)
    return 1;
  if (inColour) {
    components = 3;
  } else {
    components = 1;
  }
  
  fp = fopen (filnam, "w");
  if (fp == NULL) {
    return 2;
  }
  
  fprintf (fp, "%%!PS-Adobe-2.0 EPSF-1.2\n");
  fprintf (fp, "%%%%Title: %s\n", filnam);
  fprintf (fp, "%%%%Creator: OpenGL pixmap render output\n");
  fprintf (fp, "%%%%BoundingBox: 0 0 %d %d\n", width, height);
  fprintf (fp, "%%%%EndComments\n");
  fprintf (fp, "gsave\n");
  fprintf (fp, "/bwproc {\n");
  fprintf (fp, "    rgbproc\n");
  fprintf (fp, "    dup length 3 idiv string 0 3 0 \n");
  fprintf (fp, "    5 -1 roll {\n");
  fprintf (fp, "    add 2 1 roll 1 sub dup 0 eq\n");
  fprintf (fp, "    { pop 3 idiv 3 -1 roll dup 4 -1 roll dup\n");
  fprintf (fp, "       3 1 roll 5 -1 roll } put 1 add 3 0 \n");
  fprintf (fp, "    { 2 1 roll } ifelse\n");
  fprintf (fp, "    }forall\n");
  fprintf (fp, "    pop pop pop\n");
  fprintf (fp, "} def\n");
  fprintf (fp, "systemdict /colorimage known not {\n");
  fprintf (fp, "   /colorimage {\n");
  fprintf (fp, "       pop\n");
  fprintf (fp, "       pop\n");
  fprintf (fp, "       /rgbproc exch def\n");
  fprintf (fp, "       { bwproc } image\n");
  fprintf (fp, "   }  def\n");
  fprintf (fp, "} if\n");
  fprintf (fp, "/picstr %d string def\n", width * components);
  fprintf (fp, "%d %d scale\n", width, height);
  fprintf (fp, "%d %d %d\n", width, height, 8);
  fprintf (fp, "[%d 0 0 %d 0 0]\n", width, height);
  fprintf (fp, "{currentfile picstr readhexstring pop}\n");
  fprintf (fp, "false %d\n", components);
  fprintf (fp, "colorimage\n");
  
  curpix = (GLubyte*) pixels;
  pos = 0;
  for (i = width*height*components; i>0; i--) {
    fprintf (fp, "%02hx ", *(curpix++));
    if (++pos >= 32) {
      fprintf (fp, "\n");
      pos = 0; 
    }
  }
  if (pos)
    fprintf (fp, "\n");

  fprintf (fp, "grestore\n");
  fprintf (fp, "showpage\n");
  delete pixels;
  fclose (fp);
  return 0;
}

GLubyte* G4OpenGLXViewer::grabPixels (int inColor, unsigned int width, unsigned int height) {
  
  GLubyte* buffer;
  GLint swapbytes, lsbfirst, rowlength;
  GLint skiprows, skippixels, alignment;
  GLenum format;
  int size;

  if (inColor) {
    format = GL_RGB;
    size = width*height*3;
  } else {
    format = GL_LUMINANCE;
    size = width*height*1;
  }

  buffer = new GLubyte[size];
  if (buffer == NULL)
    return NULL;

  glGetIntegerv (GL_UNPACK_SWAP_BYTES, &swapbytes);
  glGetIntegerv (GL_UNPACK_LSB_FIRST, &lsbfirst);
  glGetIntegerv (GL_UNPACK_ROW_LENGTH, &rowlength);

  glGetIntegerv (GL_UNPACK_SKIP_ROWS, &skiprows);
  glGetIntegerv (GL_UNPACK_SKIP_PIXELS, &skippixels);
  glGetIntegerv (GL_UNPACK_ALIGNMENT, &alignment);

  glPixelStorei (GL_UNPACK_SWAP_BYTES, GL_FALSE);
  glPixelStorei (GL_UNPACK_LSB_FIRST, GL_FALSE);
  glPixelStorei (GL_UNPACK_ROW_LENGTH, 0);

  glPixelStorei (GL_UNPACK_SKIP_ROWS, 0);
  glPixelStorei (GL_UNPACK_SKIP_PIXELS, 0);
  glPixelStorei (GL_UNPACK_ALIGNMENT, 1);

  glReadPixels (0, 0, (GLsizei)width, (GLsizei)height, format, GL_UNSIGNED_BYTE, (GLvoid*) buffer);

  glPixelStorei (GL_UNPACK_SWAP_BYTES, swapbytes);
  glPixelStorei (GL_UNPACK_LSB_FIRST, lsbfirst);
  glPixelStorei (GL_UNPACK_ROW_LENGTH, rowlength);
  
  glPixelStorei (GL_UNPACK_SKIP_ROWS, skiprows);
  glPixelStorei (GL_UNPACK_SKIP_PIXELS, skippixels);
  glPixelStorei (GL_UNPACK_ALIGNMENT, alignment);
  
  return buffer;
}

#endif