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Initial check-in based on OpenGL Performer 2.4 tree.
-flynnt

/*
 * Copyright (c) 2000, Silicon Graphics, Inc.
 * ALL RIGHTS RESERVED
 *
 * This source code ("Source Code") was originally derived from a
 * code base owned by Silicon Graphics, Inc. ("SGI")
 * 
 * LICENSE: SGI grants the user ("Licensee") permission to reproduce,
 * distribute, and create derivative works from this Source Code,
 * provided that: (1) the user reproduces this entire notice within
 * both source and binary format redistributions and any accompanying
 * materials such as documentation in printed or electronic format;
 * (2) the Source Code is not to be used, or ported or modified for
 * use, except in conjunction with OpenGL Performer; and (3) the
 * names of Silicon Graphics, Inc.  and SGI may not be used in any
 * advertising or publicity relating to the Source Code without the
 * prior written permission of SGI.  No further license or permission
 * may be inferred or deemed or construed to exist with regard to the
 * Source Code or the code base of which it forms a part. All rights
 * not expressly granted are reserved.
 * 
 * This Source Code is provided to Licensee AS IS, without any
 * warranty of any kind, either express, implied, or statutory,
 * including, but not limited to, any warranty that the Source Code
 * will conform to specifications, any implied warranties of
 * merchantability, fitness for a particular purpose, and freedom
 * from infringement, and any warranty that the documentation will
 * conform to the program, or any warranty that the Source Code will
 * be error free.
 * 
 * IN NO EVENT WILL SGI BE LIABLE FOR ANY DAMAGES, INCLUDING, BUT NOT
 * LIMITED TO DIRECT, INDIRECT, SPECIAL OR CONSEQUENTIAL DAMAGES,
 * ARISING OUT OF, RESULTING FROM, OR IN ANY WAY CONNECTED WITH THE
 * SOURCE CODE, WHETHER OR NOT BASED UPON WARRANTY, CONTRACT, TORT OR
 * OTHERWISE, WHETHER OR NOT INJURY WAS SUSTAINED BY PERSONS OR
 * PROPERTY OR OTHERWISE, AND WHETHER OR NOT LOSS WAS SUSTAINED FROM,
 * OR AROSE OUT OF USE OR RESULTS FROM USE OF, OR LACK OF ABILITY TO
 * USE, THE SOURCE CODE.
 * 
 * Contact information:  Silicon Graphics, Inc., 
 * 1600 Amphitheatre Pkwy, Mountain View, CA  94043, 
 * or:  http://www.sgi.com
 */

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <math.h>

#include <Performer/pf.h>
#include <Performer/prmath.h>
#include <Performer/pfdu.h>
#include <Performer/pfutil.h>
#include <Performer/pfui.h>


/***************************************************************************/
/* 
** To be able to determine whether we are inside a fogged area or outside
** the boundary has to be closed !!! 
**
** Often, we don't need the full closed boundary when the geometry is drawn.
** The function parmeter closed then specifies, whether we have to draw all
** boundaries or not.
*/

#define SET(vec,x,y,z) \
  vec[0] = x; \
  vec[1] = y; \
  vec[2] = z;

pfNode *MakeOneLayerFog(pfBox *bbox, float top, float bottom)
{
    pfGeode *fog = pfNewGeode();
    pfGeoSet *gset = pfNewGSet(pfGetSharedArena());
    float xmin,xmax,zmin,zmax;
    int *lengths;
    pfVec3 *coords;
    int index;
    pfGeoState *gstate;

    xmin = bbox->min[0];
    xmax = bbox->max[0];
    zmin = bbox->min[1];
    zmax = bbox->max[1];

    lengths = (int *)pfMalloc(3 * sizeof(int), pfGetSharedArena());
    lengths[0] = 4;
    lengths[1] = 4;
    lengths[2] = 10;
    
    pfGSetPrimType(gset, PFGS_TRISTRIPS);
    pfGSetPrimLengths(gset, lengths);
    pfGSetNumPrims(gset, 3);
    
    coords = (pfVec3 *)pfMalloc(18 * sizeof(pfVec3), pfGetSharedArena());

    index = 0;

    /* top poly */
    SET(coords[index], xmin-1, zmin-1, top);
    index++;
    SET(coords[index], xmax+1, zmin-1, top);
    index++;
    SET(coords[index], xmin-1, zmax+1, top);
    index++;
    SET(coords[index], xmax+1, zmax+1, top);
    index++;

    /* bottom poly */
    SET(coords[index], xmin-1, zmin-1, bottom);
    index++;
    SET(coords[index], xmin-1, zmax+1, bottom);
    index++;
    SET(coords[index], xmax+1, zmin-1,  bottom);
    index++;
    SET(coords[index], xmax+1, zmax+1,  bottom);
    index++;
    
    /* sides */
    SET(coords[index], xmin-1, zmin-1, bottom);
    index++;
    SET(coords[index], xmin-1, zmin-1,  top);
    index++;
    SET(coords[index], xmin-1, zmax+1, bottom);
    index++;
    SET(coords[index], xmin-1, zmax+1,  top);
    index++;
    SET(coords[index], xmax+1, zmax+1, bottom);
    index++;
    SET(coords[index], xmax+1, zmax+1,  top);
    index++;
    SET(coords[index], xmax+1, zmin-1, bottom);
    index++;
    SET(coords[index], xmax+1, zmin-1,  top);
    index++;
    SET(coords[index], xmin-1, zmin-1, bottom);
    index++;
    SET(coords[index], xmin-1, zmin-1,  top);
    
    pfGSetAttr(gset, PFGS_COORD3, PFGS_PER_VERTEX, coords, NULL);

    gstate = pfNewGState(pfGetSharedArena());
    pfGSetGState(gset, gstate);
	
    pfAddGSet(fog, gset);
    /* XXX add a callback that would not draw the closed part if not required
     */


    return fog;
}