text: /*
      Copyright 2005-2012 Intel Corporation.  All Rights Reserved.
  
      This file is part of Threading Building Blocks.
  
      Threading Building Blocks is free software; you can redistribute it
      and/or modify it under the terms of the GNU General Public License
      version 2 as published by the Free Software Foundation.
  
      Threading Building Blocks is distributed in the hope that it will be
      useful, but WITHOUT ANY WARRANTY; without even the implied warranty
      of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
      GNU General Public License for more details.
  
      You should have received a copy of the GNU General Public License
      along with Threading Building Blocks; if not, write to the Free Software
      Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
  
      As a special exception, you may use this file as part of a free software
      library without restriction.  Specifically, if other files instantiate
      templates or use macros or inline functions from this file, or you compile
      this file and link it with other files to produce an executable, this
      file does not by itself cause the resulting executable to be covered by
      the GNU General Public License.  This exception does not however
      invalidate any other reasons why the executable file might be covered by
      the GNU General Public License.
  */
  
  /*
      The original source for this example is
      Copyright (c) 1994-2008 John E. Stone
      All rights reserved.
  
      Redistribution and use in source and binary forms, with or without
      modification, are permitted provided that the following conditions
      are met:
      1. Redistributions of source code must retain the above copyright
         notice, this list of conditions and the following disclaimer.
      2. Redistributions in binary form must reproduce the above copyright
         notice, this list of conditions and the following disclaimer in the
         documentation and/or other materials provided with the distribution.
      3. The name of the author may not be used to endorse or promote products
         derived from this software without specific prior written permission.
  
      THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS
      OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
      WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
      ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
      DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
      DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
      OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
      HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
      LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
      OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
      SUCH DAMAGE.
  */
  
  #include "machine.h"
  #include "types.h"
  #include "macros.h"
  #include "vector.h"
  #include "tgafile.h"
  #include "trace.h"
  #include "light.h"
  #include "shade.h"
  #include "camera.h"
  #include "util.h"
  #include "intersect.h"
  #include "global.h"
  #include "ui.h"
  #include "tachyon_video.h"
  
  // shared but read-only so could be private too
  static thr_parms *all_parms;
  static scenedef scene;
  static int startx;
  static int stopx;
  static int starty;
  static int stopy;
  static flt jitterscale;
  static int totaly;
  
  static color_t render_one_pixel (int x, int y, unsigned int *local_mbox, unsigned int &serial,
                                   int startx, int stopx, int starty, int stopy)
  {
      /* private vars moved inside loop */
      ray primary, sample;
      color col, avcol;
      int R,G,B;
      intersectstruct local_intersections;    
      int alias;
      /* end private */
  
      primary=camray(&scene, x, y);
      primary.intstruct = &local_intersections;
      primary.flags = RT_RAY_REGULAR;
  
      serial++;
      primary.serial = serial;  
      primary.mbox = local_mbox;
      primary.maxdist = FHUGE;
      primary.scene = &scene;
      col=trace(&primary);  
  
      serial = primary.serial;
  
      /* perform antialiasing if enabled.. */
      if (scene.antialiasing > 0) {
          for (alias=0; alias < scene.antialiasing; alias++) {
  
              serial++; /* increment serial number */
              sample=primary;  /* copy the regular primary ray to start with */
              sample.serial = serial; 
  
              {
                  sample.d.x+=((std::rand() % 100) - 50) / jitterscale;
                  sample.d.y+=((std::rand() % 100) - 50) / jitterscale;
                  sample.d.z+=((std::rand() % 100) - 50) / jitterscale;
              }
  
              avcol=trace(&sample);  
  
              serial = sample.serial; /* update our overall serial # */
  
              col.r += avcol.r;
              col.g += avcol.g;
              col.b += avcol.b;
          }
  
          col.r /= (scene.antialiasing + 1.0);
          col.g /= (scene.antialiasing + 1.0);
          col.b /= (scene.antialiasing + 1.0);
      }
  
      /* Handle overexposure and underexposure here... */
      R=(int) (col.r*255);
      if (R > 255) R = 255;
      else if (R < 0) R = 0;
  
      G=(int) (col.g*255);
      if (G > 255) G = 255;
      else if (G < 0) G = 0;
  
      B=(int) (col.b*255);
      if (B > 255) B = 255;
      else if (B < 0) B = 0;
  
      return video->get_color(R, G, B);
  
  }
  
  static void parallel_thread (void)
  {
      // thread-local storage
      unsigned int serial = 1;
      unsigned int mboxsize = sizeof(unsigned int)*(max_objectid() + 20);
      unsigned int * local_mbox = (unsigned int *) alloca(mboxsize);
      memset(local_mbox,0,mboxsize);
  
      for (int y = starty; y < stopy; y++) { {
          drawing_area drawing(startx, totaly-y, stopx-startx, 1);
          for (int x = startx; x < stopx; x++) {
              color_t c = render_one_pixel (x, y, local_mbox, serial, startx, stopx, starty, stopy);
              drawing.put_pixel(c);
          } }
          if(!video->next_frame()) return;
      }
  }
  
  void * thread_trace(thr_parms * parms)
  {
      // shared but read-only so could be private too
      all_parms = parms;
      scene = parms->scene;
      startx = parms->startx;
      stopx = parms->stopx;
      starty = parms->starty;
      stopy = parms->stopy;
      jitterscale = 40.0*(scene.hres + scene.vres);
      totaly = parms->scene.vres-1;
  
      parallel_thread ();
  
      return(NULL);  
  }
  