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#ifndef lint
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static const char RCSid[] = "$Id$";
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#endif
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/*
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* face.c - routines dealing with polygonal faces.
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*/
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/* ====================================================================
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* The Radiance Software License, Version 1.0
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*
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* Copyright (c) 1990 - 2002 The Regents of the University of California,
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* through Lawrence Berkeley National Laboratory. All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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*
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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*
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in
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* the documentation and/or other materials provided with the
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* distribution.
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*
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* 3. The end-user documentation included with the redistribution,
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* if any, must include the following acknowledgment:
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* "This product includes Radiance software
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* (http://radsite.lbl.gov/)
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* developed by the Lawrence Berkeley National Laboratory
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* (http://www.lbl.gov/)."
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* Alternately, this acknowledgment may appear in the software itself,
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* if and wherever such third-party acknowledgments normally appear.
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*
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* 4. The names "Radiance," "Lawrence Berkeley National Laboratory"
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* and "The Regents of the University of California" must
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* not be used to endorse or promote products derived from this
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* software without prior written permission. For written
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* permission, please contact [email protected].
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*
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* 5. Products derived from this software may not be called "Radiance",
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* nor may "Radiance" appear in their name, without prior written
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* permission of Lawrence Berkeley National Laboratory.
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*
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* THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
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* WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
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* DISCLAIMED. IN NO EVENT SHALL Lawrence Berkeley National Laboratory OR
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* ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
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* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
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* USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
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* ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
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* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
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* OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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* ====================================================================
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*
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* This software consists of voluntary contributions made by many
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* individuals on behalf of Lawrence Berkeley National Laboratory. For more
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* information on Lawrence Berkeley National Laboratory, please see
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* <http://www.lbl.gov/>.
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*/
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#include "standard.h"
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#include "object.h"
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#include "face.h"
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/*
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* A face is given as a list of 3D vertices. The normal
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* direction and therefore the surface orientation is determined
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* by the ordering of the vertices. Looking in the direction opposite
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* the normal (at the front of the face), the vertices will be
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* listed in counter-clockwise order.
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* There is no checking done to insure that the edges do not cross
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* one another. This was considered too expensive and should be unnecessary.
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* The last vertex is automatically connected to the first.
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*/
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#ifdef SMLFLT
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#define VERTEPS 1e-2 /* allowed vertex error */
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#else
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#define VERTEPS 1e-4 /* allowed vertex error */
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#endif
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FACE *
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getface(o) /* get arguments for a face */
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OBJREC *o;
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{
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double d1;
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int badvert;
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FVECT v1, v2, v3;
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register FACE *f;
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register int i;
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if ((f = (FACE *)o->os) != NULL)
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return(f); /* already done */
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f = (FACE *)malloc(sizeof(FACE));
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if (f == NULL)
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error(SYSTEM, "out of memory in makeface");
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if (o->oargs.nfargs < 9 || o->oargs.nfargs % 3)
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objerror(o, USER, "bad # arguments");
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o->os = (char *)f; /* save face */
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f->va = o->oargs.farg;
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f->nv = o->oargs.nfargs / 3;
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/* check for last==first */
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if (dist2(VERTEX(f,0),VERTEX(f,f->nv-1)) <= FTINY*FTINY)
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f->nv--;
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/* compute area and normal */
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f->norm[0] = f->norm[1] = f->norm[2] = 0.0;
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v1[0] = VERTEX(f,1)[0] - VERTEX(f,0)[0];
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v1[1] = VERTEX(f,1)[1] - VERTEX(f,0)[1];
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v1[2] = VERTEX(f,1)[2] - VERTEX(f,0)[2];
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for (i = 2; i < f->nv; i++) {
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v2[0] = VERTEX(f,i)[0] - VERTEX(f,0)[0];
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v2[1] = VERTEX(f,i)[1] - VERTEX(f,0)[1];
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v2[2] = VERTEX(f,i)[2] - VERTEX(f,0)[2];
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fcross(v3, v1, v2);
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f->norm[0] += v3[0];
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f->norm[1] += v3[1];
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f->norm[2] += v3[2];
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VCOPY(v1, v2);
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}
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f->area = normalize(f->norm);
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if (f->area == 0.0) {
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objerror(o, WARNING, "zero area"); /* used to be fatal */
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f->offset = 0.0;
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f->ax = 0;
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return(f);
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}
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f->area *= 0.5;
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/* compute offset */
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badvert = 0;
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f->offset = DOT(f->norm, VERTEX(f,0));
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for (i = 1; i < f->nv; i++) {
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d1 = DOT(f->norm, VERTEX(f,i));
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badvert += fabs(d1 - f->offset/i) > VERTEPS;
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f->offset += d1;
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}
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f->offset /= (double)f->nv;
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if (badvert)
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objerror(o, WARNING, "non-planar vertex");
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/* find axis */
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f->ax = fabs(f->norm[0]) > fabs(f->norm[1]) ? 0 : 1;
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if (fabs(f->norm[2]) > fabs(f->norm[f->ax]))
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f->ax = 2;
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return(f);
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}
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void
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freeface(o) /* free memory associated with face */
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OBJREC *o;
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{
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if (o->os == NULL)
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return;
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free(o->os);
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o->os = NULL;
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}
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int
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inface(p, f) /* determine if point is in face */
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FVECT p;
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FACE *f;
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{
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int ncross, n;
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double x, y;
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register int xi, yi;
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register FLOAT *p0, *p1;
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xi = (f->ax+1)%3;
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yi = (f->ax+2)%3;
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x = p[xi];
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y = p[yi];
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n = f->nv;
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p0 = f->va + 3*(n-1); /* connect last to first */
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p1 = f->va;
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ncross = 0;
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/* positive x axis cross test */
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while (n--) {
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if ((p0[yi] > y) ^ (p1[yi] > y))
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if (p0[xi] > x && p1[xi] > x)
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ncross++;
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else if (p0[xi] > x || p1[xi] > x)
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ncross += (p1[yi] > p0[yi]) ^
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((p0[yi]-y)*(p1[xi]-x) >
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(p0[xi]-x)*(p1[yi]-y));
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p0 = p1;
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p1 += 3;
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}
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return(ncross & 01);
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}
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