GL2PSDLL_API GLint gl2psBeginPage(const char *title, const char *producer, 
                                  GLint viewport[4], GLint format, GLint sort,
                                  GLint options, GLint colormode,
                                  GLint colorsize, GL2PSrgba *colormap,
                                  GLint nr, GLint ng, GLint nb, GLint buffersize,
                                  FILE *stream, const char *filename)
{
  GLint index;
  int i;

  if(gl2ps){
    gl2psMsg(GL2PS_ERROR, "gl2psBeginPage called in wrong program state");
    return GL2PS_ERROR;
  }

  gl2ps = (GL2PScontext*)gl2psMalloc(sizeof(GL2PScontext));

  if(format >= 0 && format < (GLint)(sizeof(gl2psbackends)/sizeof(gl2psbackends[0]))){
    gl2ps->format = format;
  }
  else {
    gl2psMsg(GL2PS_ERROR, "Unknown output format: %d", format);
    gl2psFree(gl2ps);
    gl2ps = NULL;
    return GL2PS_ERROR;
  }

  switch(sort){
  case GL2PS_NO_SORT :
  case GL2PS_SIMPLE_SORT :
  case GL2PS_BSP_SORT :
    gl2ps->sort = sort;
    break;
  default :
    gl2psMsg(GL2PS_ERROR, "Unknown sorting algorithm: %d", sort);
    gl2psFree(gl2ps);
    gl2ps = NULL;
    return GL2PS_ERROR;
  }

  if(stream){
    gl2ps->stream = stream;
  }
  else{
    gl2psMsg(GL2PS_ERROR, "Bad file pointer");
    gl2psFree(gl2ps);
    gl2ps = NULL;
    return GL2PS_ERROR;
  }

  gl2ps->header = GL_TRUE;
  gl2ps->maxbestroot = 10;
  gl2ps->options = options;
  gl2ps->compress = NULL;
  gl2ps->imagemap_head = NULL;
  gl2ps->imagemap_tail = NULL;

  if(gl2ps->options & GL2PS_USE_CURRENT_VIEWPORT){
    glGetIntegerv(GL_VIEWPORT, gl2ps->viewport);
  }
  else{
    for(i = 0; i < 4; i++){
      gl2ps->viewport[i] = viewport[i];
    }
  }

  if(!gl2ps->viewport[2] || !gl2ps->viewport[3]){
    gl2psMsg(GL2PS_ERROR, "Incorrect viewport (x=%d, y=%d, width=%d, height=%d)",
             gl2ps->viewport[0], gl2ps->viewport[1], 
             gl2ps->viewport[2], gl2ps->viewport[3]);
    gl2psFree(gl2ps);
    gl2ps = NULL;
    return GL2PS_ERROR;
  }

  gl2ps->threshold[0] = nr ? 1.0F/(GLfloat)nr : 0.064F;
  gl2ps->threshold[1] = ng ? 1.0F/(GLfloat)ng : 0.034F;
  gl2ps->threshold[2] = nb ? 1.0F/(GLfloat)nb : 0.100F;
  gl2ps->colormode = colormode;
  gl2ps->buffersize = buffersize > 0 ? buffersize : 2048 * 2048;
  for(i = 0; i < 3; i++){
    gl2ps->lastvertex.xyz[i] = -1.0F;
  }
  for(i = 0; i < 4; i++){
    gl2ps->lastvertex.rgba[i] = -1.0F;
    gl2ps->lastrgba[i] = -1.0F;
  }
  gl2ps->lastlinewidth = -1.0F;
  gl2ps->lastpattern = 0;
  gl2ps->lastfactor = 0;
  gl2ps->imagetree = NULL;
  gl2ps->primitivetoadd = NULL;
  gl2ps->zerosurfacearea = GL_FALSE;  
  gl2ps->pdfprimlist = NULL;
  gl2ps->pdfgrouplist = NULL;
  gl2ps->xreflist = NULL;
  
  /* get default blending mode from current OpenGL state (enabled by
     default for SVG) */
  gl2ps->blending = (gl2ps->format == GL2PS_SVG) ? GL_TRUE : glIsEnabled(GL_BLEND);
  glGetIntegerv(GL_BLEND_SRC, &gl2ps->blendfunc[0]);
  glGetIntegerv(GL_BLEND_DST, &gl2ps->blendfunc[1]);

  if(gl2ps->colormode == GL_RGBA){
    gl2ps->colorsize = 0;
    gl2ps->colormap = NULL;
    glGetFloatv(GL_COLOR_CLEAR_VALUE, gl2ps->bgcolor);
  }
  else if(gl2ps->colormode == GL_COLOR_INDEX){
    if(!colorsize || !colormap){
      gl2psMsg(GL2PS_ERROR, "Missing colormap for GL_COLOR_INDEX rendering");
      gl2psFree(gl2ps);
      gl2ps = NULL;
      return GL2PS_ERROR;
    }
    gl2ps->colorsize = colorsize;
    gl2ps->colormap = (GL2PSrgba*)gl2psMalloc(gl2ps->colorsize * sizeof(GL2PSrgba));
    memcpy(gl2ps->colormap, colormap, gl2ps->colorsize * sizeof(GL2PSrgba));
    glGetIntegerv(GL_INDEX_CLEAR_VALUE, &index);
    gl2ps->bgcolor[0] = gl2ps->colormap[index][0];
    gl2ps->bgcolor[1] = gl2ps->colormap[index][1];
    gl2ps->bgcolor[2] = gl2ps->colormap[index][2];
    gl2ps->bgcolor[3] = 1.0F;
  }
  else{
    gl2psMsg(GL2PS_ERROR, "Unknown color mode in gl2psBeginPage");
    gl2psFree(gl2ps);
    gl2ps = NULL;
    return GL2PS_ERROR;
  }

  if(!title){
    gl2ps->title = (char*)gl2psMalloc(sizeof(char));
    gl2ps->title[0] = '\0';
  }
  else{
    gl2ps->title = (char*)gl2psMalloc((strlen(title)+1)*sizeof(char));
    strcpy(gl2ps->title, title);
  }
    
  if(!producer){
    gl2ps->producer = (char*)gl2psMalloc(sizeof(char));
    gl2ps->producer[0] = '\0';
  }
  else{
    gl2ps->producer = (char*)gl2psMalloc((strlen(producer)+1)*sizeof(char));
    strcpy(gl2ps->producer, producer);
  }
  
  if(!filename){
    gl2ps->filename = (char*)gl2psMalloc(sizeof(char));
    gl2ps->filename[0] = '\0';
  }
  else{
    gl2ps->filename = (char*)gl2psMalloc((strlen(filename)+1)*sizeof(char));
    strcpy(gl2ps->filename, filename);
  }

  gl2ps->primitives = gl2psListCreate(500, 500, sizeof(GL2PSprimitive*));
  gl2ps->auxprimitives = gl2psListCreate(100, 100, sizeof(GL2PSprimitive*));
  gl2ps->feedback = (GLfloat*)gl2psMalloc(gl2ps->buffersize * sizeof(GLfloat));
  glFeedbackBuffer(gl2ps->buffersize, GL_3D_COLOR, gl2ps->feedback);
  glRenderMode(GL_FEEDBACK);  

  return GL2PS_SUCCESS;
}