11cab2921ab279367f8206cdadc9259d12e603548Derek Sollenberger/* 21cab2921ab279367f8206cdadc9259d12e603548Derek Sollenberger** License Applicability. Except to the extent portions of this file are 31cab2921ab279367f8206cdadc9259d12e603548Derek Sollenberger** made subject to an alternative license as permitted in the SGI Free 41cab2921ab279367f8206cdadc9259d12e603548Derek Sollenberger** Software License B, Version 1.1 (the "License"), the contents of this 51cab2921ab279367f8206cdadc9259d12e603548Derek Sollenberger** file are subject only to the provisions of the License. You may not use 61cab2921ab279367f8206cdadc9259d12e603548Derek Sollenberger** this file except in compliance with the License. You may obtain a copy 71cab2921ab279367f8206cdadc9259d12e603548Derek Sollenberger** of the License at Silicon Graphics, Inc., attn: Legal Services, 1600 81cab2921ab279367f8206cdadc9259d12e603548Derek Sollenberger** Amphitheatre Parkway, Mountain View, CA 94043-1351, or at: 91cab2921ab279367f8206cdadc9259d12e603548Derek Sollenberger** 101cab2921ab279367f8206cdadc9259d12e603548Derek Sollenberger** http://oss.sgi.com/projects/FreeB 111cab2921ab279367f8206cdadc9259d12e603548Derek Sollenberger** 121cab2921ab279367f8206cdadc9259d12e603548Derek Sollenberger** Note that, as provided in the License, the Software is distributed on an 131cab2921ab279367f8206cdadc9259d12e603548Derek Sollenberger** "AS IS" basis, with ALL EXPRESS AND IMPLIED WARRANTIES AND CONDITIONS 141cab2921ab279367f8206cdadc9259d12e603548Derek Sollenberger** DISCLAIMED, INCLUDING, WITHOUT LIMITATION, ANY IMPLIED WARRANTIES AND 151cab2921ab279367f8206cdadc9259d12e603548Derek Sollenberger** CONDITIONS OF MERCHANTABILITY, SATISFACTORY QUALITY, FITNESS FOR A 161cab2921ab279367f8206cdadc9259d12e603548Derek Sollenberger** PARTICULAR PURPOSE, AND NON-INFRINGEMENT. 171cab2921ab279367f8206cdadc9259d12e603548Derek Sollenberger** 181cab2921ab279367f8206cdadc9259d12e603548Derek Sollenberger** Original Code. The Original Code is: OpenGL Sample Implementation, 191cab2921ab279367f8206cdadc9259d12e603548Derek Sollenberger** Version 1.2.1, released January 26, 2000, developed by Silicon Graphics, 201cab2921ab279367f8206cdadc9259d12e603548Derek Sollenberger** Inc. The Original Code is Copyright (c) 1991-2000 Silicon Graphics, Inc. 211cab2921ab279367f8206cdadc9259d12e603548Derek Sollenberger** Copyright in any portions created by third parties is as indicated 221cab2921ab279367f8206cdadc9259d12e603548Derek Sollenberger** elsewhere herein. All Rights Reserved. 231cab2921ab279367f8206cdadc9259d12e603548Derek Sollenberger** 241cab2921ab279367f8206cdadc9259d12e603548Derek Sollenberger** Additional Notice Provisions: The application programming interfaces 251cab2921ab279367f8206cdadc9259d12e603548Derek Sollenberger** established by SGI in conjunction with the Original Code are The 261cab2921ab279367f8206cdadc9259d12e603548Derek Sollenberger** OpenGL(R) Graphics System: A Specification (Version 1.2.1), released 271cab2921ab279367f8206cdadc9259d12e603548Derek Sollenberger** April 1, 1999; The OpenGL(R) Graphics System Utility Library (Version 281cab2921ab279367f8206cdadc9259d12e603548Derek Sollenberger** 1.3), released November 4, 1998; and OpenGL(R) Graphics with the X 291cab2921ab279367f8206cdadc9259d12e603548Derek Sollenberger** Window System(R) (Version 1.3), released October 19, 1998. This software 301cab2921ab279367f8206cdadc9259d12e603548Derek Sollenberger** was created using the OpenGL(R) version 1.2.1 Sample Implementation 311cab2921ab279367f8206cdadc9259d12e603548Derek Sollenberger** published by SGI, but has not been independently verified as being 321cab2921ab279367f8206cdadc9259d12e603548Derek Sollenberger** compliant with the OpenGL(R) version 1.2.1 Specification. 331cab2921ab279367f8206cdadc9259d12e603548Derek Sollenberger** 341cab2921ab279367f8206cdadc9259d12e603548Derek Sollenberger*/ 351cab2921ab279367f8206cdadc9259d12e603548Derek Sollenberger/* 361cab2921ab279367f8206cdadc9259d12e603548Derek Sollenberger** Author: Eric Veach, July 1994. 371cab2921ab279367f8206cdadc9259d12e603548Derek Sollenberger** 381cab2921ab279367f8206cdadc9259d12e603548Derek Sollenberger** $Date$ $Revision$ 391cab2921ab279367f8206cdadc9259d12e603548Derek Sollenberger** $Header: //depot/main/gfx/lib/glu/libtess/normal.c#5 $ 401cab2921ab279367f8206cdadc9259d12e603548Derek Sollenberger*/ 411cab2921ab279367f8206cdadc9259d12e603548Derek Sollenberger 421cab2921ab279367f8206cdadc9259d12e603548Derek Sollenberger#include "gluos.h" 431cab2921ab279367f8206cdadc9259d12e603548Derek Sollenberger#include "mesh.h" 441cab2921ab279367f8206cdadc9259d12e603548Derek Sollenberger#include "tess.h" 451cab2921ab279367f8206cdadc9259d12e603548Derek Sollenberger#include "normal.h" 461cab2921ab279367f8206cdadc9259d12e603548Derek Sollenberger#include <math.h> 471cab2921ab279367f8206cdadc9259d12e603548Derek Sollenberger#include <assert.h> 481cab2921ab279367f8206cdadc9259d12e603548Derek Sollenberger 491cab2921ab279367f8206cdadc9259d12e603548Derek Sollenberger#define TRUE 1 501cab2921ab279367f8206cdadc9259d12e603548Derek Sollenberger#define FALSE 0 511cab2921ab279367f8206cdadc9259d12e603548Derek Sollenberger 521cab2921ab279367f8206cdadc9259d12e603548Derek Sollenberger#define Dot(u,v) (u[0]*v[0] + u[1]*v[1] + u[2]*v[2]) 531cab2921ab279367f8206cdadc9259d12e603548Derek Sollenberger 541cab2921ab279367f8206cdadc9259d12e603548Derek Sollenberger#if defined(FOR_TRITE_TEST_PROGRAM) || defined(TRUE_PROJECT) 551cab2921ab279367f8206cdadc9259d12e603548Derek Sollenbergerstatic void Normalize( GLdouble v[3] ) 561cab2921ab279367f8206cdadc9259d12e603548Derek Sollenberger{ 571cab2921ab279367f8206cdadc9259d12e603548Derek Sollenberger GLdouble len = v[0]*v[0] + v[1]*v[1] + v[2]*v[2]; 581cab2921ab279367f8206cdadc9259d12e603548Derek Sollenberger 591cab2921ab279367f8206cdadc9259d12e603548Derek Sollenberger assert( len > 0 ); 601cab2921ab279367f8206cdadc9259d12e603548Derek Sollenberger len = sqrt( len ); 611cab2921ab279367f8206cdadc9259d12e603548Derek Sollenberger v[0] /= len; 621cab2921ab279367f8206cdadc9259d12e603548Derek Sollenberger v[1] /= len; 631cab2921ab279367f8206cdadc9259d12e603548Derek Sollenberger v[2] /= len; 641cab2921ab279367f8206cdadc9259d12e603548Derek Sollenberger} 651cab2921ab279367f8206cdadc9259d12e603548Derek Sollenberger#endif 661cab2921ab279367f8206cdadc9259d12e603548Derek Sollenberger 671cab2921ab279367f8206cdadc9259d12e603548Derek Sollenberger#define ABS(x) ((x) < 0 ? -(x) : (x)) 681cab2921ab279367f8206cdadc9259d12e603548Derek Sollenberger 691cab2921ab279367f8206cdadc9259d12e603548Derek Sollenbergerstatic int LongAxis( GLdouble v[3] ) 701cab2921ab279367f8206cdadc9259d12e603548Derek Sollenberger{ 711cab2921ab279367f8206cdadc9259d12e603548Derek Sollenberger int i = 0; 721cab2921ab279367f8206cdadc9259d12e603548Derek Sollenberger 731cab2921ab279367f8206cdadc9259d12e603548Derek Sollenberger if( ABS(v[1]) > ABS(v[0]) ) { i = 1; } 741cab2921ab279367f8206cdadc9259d12e603548Derek Sollenberger if( ABS(v[2]) > ABS(v[i]) ) { i = 2; } 751cab2921ab279367f8206cdadc9259d12e603548Derek Sollenberger return i; 761cab2921ab279367f8206cdadc9259d12e603548Derek Sollenberger} 771cab2921ab279367f8206cdadc9259d12e603548Derek Sollenberger 781cab2921ab279367f8206cdadc9259d12e603548Derek Sollenbergerstatic void ComputeNormal( GLUtesselator *tess, GLdouble norm[3] ) 791cab2921ab279367f8206cdadc9259d12e603548Derek Sollenberger{ 801cab2921ab279367f8206cdadc9259d12e603548Derek Sollenberger GLUvertex *v, *v1, *v2; 811cab2921ab279367f8206cdadc9259d12e603548Derek Sollenberger GLdouble c, tLen2, maxLen2; 821cab2921ab279367f8206cdadc9259d12e603548Derek Sollenberger GLdouble maxVal[3], minVal[3], d1[3], d2[3], tNorm[3]; 831cab2921ab279367f8206cdadc9259d12e603548Derek Sollenberger GLUvertex *maxVert[3], *minVert[3]; 841cab2921ab279367f8206cdadc9259d12e603548Derek Sollenberger GLUvertex *vHead = &tess->mesh->vHead; 851cab2921ab279367f8206cdadc9259d12e603548Derek Sollenberger int i; 861cab2921ab279367f8206cdadc9259d12e603548Derek Sollenberger 871cab2921ab279367f8206cdadc9259d12e603548Derek Sollenberger maxVal[0] = maxVal[1] = maxVal[2] = -2 * GLU_TESS_MAX_COORD; 881cab2921ab279367f8206cdadc9259d12e603548Derek Sollenberger minVal[0] = minVal[1] = minVal[2] = 2 * GLU_TESS_MAX_COORD; 891cab2921ab279367f8206cdadc9259d12e603548Derek Sollenberger 901cab2921ab279367f8206cdadc9259d12e603548Derek Sollenberger for( v = vHead->next; v != vHead; v = v->next ) { 911cab2921ab279367f8206cdadc9259d12e603548Derek Sollenberger for( i = 0; i < 3; ++i ) { 921cab2921ab279367f8206cdadc9259d12e603548Derek Sollenberger c = v->coords[i]; 931cab2921ab279367f8206cdadc9259d12e603548Derek Sollenberger if( c < minVal[i] ) { minVal[i] = c; minVert[i] = v; } 941cab2921ab279367f8206cdadc9259d12e603548Derek Sollenberger if( c > maxVal[i] ) { maxVal[i] = c; maxVert[i] = v; } 951cab2921ab279367f8206cdadc9259d12e603548Derek Sollenberger } 961cab2921ab279367f8206cdadc9259d12e603548Derek Sollenberger } 971cab2921ab279367f8206cdadc9259d12e603548Derek Sollenberger 981cab2921ab279367f8206cdadc9259d12e603548Derek Sollenberger /* Find two vertices separated by at least 1/sqrt(3) of the maximum 991cab2921ab279367f8206cdadc9259d12e603548Derek Sollenberger * distance between any two vertices 1001cab2921ab279367f8206cdadc9259d12e603548Derek Sollenberger */ 1011cab2921ab279367f8206cdadc9259d12e603548Derek Sollenberger i = 0; 1021cab2921ab279367f8206cdadc9259d12e603548Derek Sollenberger if( maxVal[1] - minVal[1] > maxVal[0] - minVal[0] ) { i = 1; } 1031cab2921ab279367f8206cdadc9259d12e603548Derek Sollenberger if( maxVal[2] - minVal[2] > maxVal[i] - minVal[i] ) { i = 2; } 1041cab2921ab279367f8206cdadc9259d12e603548Derek Sollenberger if( minVal[i] >= maxVal[i] ) { 1051cab2921ab279367f8206cdadc9259d12e603548Derek Sollenberger /* All vertices are the same -- normal doesn't matter */ 1061cab2921ab279367f8206cdadc9259d12e603548Derek Sollenberger norm[0] = 0; norm[1] = 0; norm[2] = 1; 1071cab2921ab279367f8206cdadc9259d12e603548Derek Sollenberger return; 1081cab2921ab279367f8206cdadc9259d12e603548Derek Sollenberger } 1091cab2921ab279367f8206cdadc9259d12e603548Derek Sollenberger 1101cab2921ab279367f8206cdadc9259d12e603548Derek Sollenberger /* Look for a third vertex which forms the triangle with maximum area 1111cab2921ab279367f8206cdadc9259d12e603548Derek Sollenberger * (Length of normal == twice the triangle area) 1121cab2921ab279367f8206cdadc9259d12e603548Derek Sollenberger */ 1131cab2921ab279367f8206cdadc9259d12e603548Derek Sollenberger maxLen2 = 0; 1141cab2921ab279367f8206cdadc9259d12e603548Derek Sollenberger v1 = minVert[i]; 1151cab2921ab279367f8206cdadc9259d12e603548Derek Sollenberger v2 = maxVert[i]; 1161cab2921ab279367f8206cdadc9259d12e603548Derek Sollenberger d1[0] = v1->coords[0] - v2->coords[0]; 1171cab2921ab279367f8206cdadc9259d12e603548Derek Sollenberger d1[1] = v1->coords[1] - v2->coords[1]; 1181cab2921ab279367f8206cdadc9259d12e603548Derek Sollenberger d1[2] = v1->coords[2] - v2->coords[2]; 1191cab2921ab279367f8206cdadc9259d12e603548Derek Sollenberger for( v = vHead->next; v != vHead; v = v->next ) { 1201cab2921ab279367f8206cdadc9259d12e603548Derek Sollenberger d2[0] = v->coords[0] - v2->coords[0]; 1211cab2921ab279367f8206cdadc9259d12e603548Derek Sollenberger d2[1] = v->coords[1] - v2->coords[1]; 1221cab2921ab279367f8206cdadc9259d12e603548Derek Sollenberger d2[2] = v->coords[2] - v2->coords[2]; 1231cab2921ab279367f8206cdadc9259d12e603548Derek Sollenberger tNorm[0] = d1[1]*d2[2] - d1[2]*d2[1]; 1241cab2921ab279367f8206cdadc9259d12e603548Derek Sollenberger tNorm[1] = d1[2]*d2[0] - d1[0]*d2[2]; 1251cab2921ab279367f8206cdadc9259d12e603548Derek Sollenberger tNorm[2] = d1[0]*d2[1] - d1[1]*d2[0]; 1261cab2921ab279367f8206cdadc9259d12e603548Derek Sollenberger tLen2 = tNorm[0]*tNorm[0] + tNorm[1]*tNorm[1] + tNorm[2]*tNorm[2]; 1271cab2921ab279367f8206cdadc9259d12e603548Derek Sollenberger if( tLen2 > maxLen2 ) { 1281cab2921ab279367f8206cdadc9259d12e603548Derek Sollenberger maxLen2 = tLen2; 1291cab2921ab279367f8206cdadc9259d12e603548Derek Sollenberger norm[0] = tNorm[0]; 1301cab2921ab279367f8206cdadc9259d12e603548Derek Sollenberger norm[1] = tNorm[1]; 1311cab2921ab279367f8206cdadc9259d12e603548Derek Sollenberger norm[2] = tNorm[2]; 1321cab2921ab279367f8206cdadc9259d12e603548Derek Sollenberger } 1331cab2921ab279367f8206cdadc9259d12e603548Derek Sollenberger } 1341cab2921ab279367f8206cdadc9259d12e603548Derek Sollenberger 1351cab2921ab279367f8206cdadc9259d12e603548Derek Sollenberger if( maxLen2 <= 0 ) { 1361cab2921ab279367f8206cdadc9259d12e603548Derek Sollenberger /* All points lie on a single line -- any decent normal will do */ 1371cab2921ab279367f8206cdadc9259d12e603548Derek Sollenberger norm[0] = norm[1] = norm[2] = 0; 1381cab2921ab279367f8206cdadc9259d12e603548Derek Sollenberger norm[LongAxis(d1)] = 1; 1391cab2921ab279367f8206cdadc9259d12e603548Derek Sollenberger } 1401cab2921ab279367f8206cdadc9259d12e603548Derek Sollenberger} 1411cab2921ab279367f8206cdadc9259d12e603548Derek Sollenberger 1421cab2921ab279367f8206cdadc9259d12e603548Derek Sollenberger 1431cab2921ab279367f8206cdadc9259d12e603548Derek Sollenbergerstatic void CheckOrientation( GLUtesselator *tess ) 1441cab2921ab279367f8206cdadc9259d12e603548Derek Sollenberger{ 1451cab2921ab279367f8206cdadc9259d12e603548Derek Sollenberger GLdouble area; 1461cab2921ab279367f8206cdadc9259d12e603548Derek Sollenberger GLUface *f, *fHead = &tess->mesh->fHead; 1471cab2921ab279367f8206cdadc9259d12e603548Derek Sollenberger GLUvertex *v, *vHead = &tess->mesh->vHead; 1481cab2921ab279367f8206cdadc9259d12e603548Derek Sollenberger GLUhalfEdge *e; 1491cab2921ab279367f8206cdadc9259d12e603548Derek Sollenberger 1501cab2921ab279367f8206cdadc9259d12e603548Derek Sollenberger /* When we compute the normal automatically, we choose the orientation 1511cab2921ab279367f8206cdadc9259d12e603548Derek Sollenberger * so that the the sum of the signed areas of all contours is non-negative. 1521cab2921ab279367f8206cdadc9259d12e603548Derek Sollenberger */ 1531cab2921ab279367f8206cdadc9259d12e603548Derek Sollenberger area = 0; 1541cab2921ab279367f8206cdadc9259d12e603548Derek Sollenberger for( f = fHead->next; f != fHead; f = f->next ) { 1551cab2921ab279367f8206cdadc9259d12e603548Derek Sollenberger e = f->anEdge; 1561cab2921ab279367f8206cdadc9259d12e603548Derek Sollenberger if( e->winding <= 0 ) continue; 1571cab2921ab279367f8206cdadc9259d12e603548Derek Sollenberger do { 1581cab2921ab279367f8206cdadc9259d12e603548Derek Sollenberger area += (e->Org->s - e->Dst->s) * (e->Org->t + e->Dst->t); 1591cab2921ab279367f8206cdadc9259d12e603548Derek Sollenberger e = e->Lnext; 1601cab2921ab279367f8206cdadc9259d12e603548Derek Sollenberger } while( e != f->anEdge ); 1611cab2921ab279367f8206cdadc9259d12e603548Derek Sollenberger } 1621cab2921ab279367f8206cdadc9259d12e603548Derek Sollenberger if( area < 0 ) { 1631cab2921ab279367f8206cdadc9259d12e603548Derek Sollenberger /* Reverse the orientation by flipping all the t-coordinates */ 1641cab2921ab279367f8206cdadc9259d12e603548Derek Sollenberger for( v = vHead->next; v != vHead; v = v->next ) { 1651cab2921ab279367f8206cdadc9259d12e603548Derek Sollenberger v->t = - v->t; 1661cab2921ab279367f8206cdadc9259d12e603548Derek Sollenberger } 1671cab2921ab279367f8206cdadc9259d12e603548Derek Sollenberger tess->tUnit[0] = - tess->tUnit[0]; 1681cab2921ab279367f8206cdadc9259d12e603548Derek Sollenberger tess->tUnit[1] = - tess->tUnit[1]; 1691cab2921ab279367f8206cdadc9259d12e603548Derek Sollenberger tess->tUnit[2] = - tess->tUnit[2]; 1701cab2921ab279367f8206cdadc9259d12e603548Derek Sollenberger } 1711cab2921ab279367f8206cdadc9259d12e603548Derek Sollenberger} 1721cab2921ab279367f8206cdadc9259d12e603548Derek Sollenberger 1731cab2921ab279367f8206cdadc9259d12e603548Derek Sollenberger#ifdef FOR_TRITE_TEST_PROGRAM 1741cab2921ab279367f8206cdadc9259d12e603548Derek Sollenberger#include <stdlib.h> 1751cab2921ab279367f8206cdadc9259d12e603548Derek Sollenbergerextern int RandomSweep; 1761cab2921ab279367f8206cdadc9259d12e603548Derek Sollenberger#define S_UNIT_X (RandomSweep ? (2*drand48()-1) : 1.0) 1771cab2921ab279367f8206cdadc9259d12e603548Derek Sollenberger#define S_UNIT_Y (RandomSweep ? (2*drand48()-1) : 0.0) 1781cab2921ab279367f8206cdadc9259d12e603548Derek Sollenberger#else 1791cab2921ab279367f8206cdadc9259d12e603548Derek Sollenberger#if defined(SLANTED_SWEEP) 1801cab2921ab279367f8206cdadc9259d12e603548Derek Sollenberger/* The "feature merging" is not intended to be complete. There are 1811cab2921ab279367f8206cdadc9259d12e603548Derek Sollenberger * special cases where edges are nearly parallel to the sweep line 1821cab2921ab279367f8206cdadc9259d12e603548Derek Sollenberger * which are not implemented. The algorithm should still behave 1831cab2921ab279367f8206cdadc9259d12e603548Derek Sollenberger * robustly (ie. produce a reasonable tesselation) in the presence 1841cab2921ab279367f8206cdadc9259d12e603548Derek Sollenberger * of such edges, however it may miss features which could have been 1851cab2921ab279367f8206cdadc9259d12e603548Derek Sollenberger * merged. We could minimize this effect by choosing the sweep line 1861cab2921ab279367f8206cdadc9259d12e603548Derek Sollenberger * direction to be something unusual (ie. not parallel to one of the 1871cab2921ab279367f8206cdadc9259d12e603548Derek Sollenberger * coordinate axes). 1881cab2921ab279367f8206cdadc9259d12e603548Derek Sollenberger */ 1891cab2921ab279367f8206cdadc9259d12e603548Derek Sollenberger#define S_UNIT_X 0.50941539564955385 /* Pre-normalized */ 1901cab2921ab279367f8206cdadc9259d12e603548Derek Sollenberger#define S_UNIT_Y 0.86052074622010633 1911cab2921ab279367f8206cdadc9259d12e603548Derek Sollenberger#else 1921cab2921ab279367f8206cdadc9259d12e603548Derek Sollenberger#define S_UNIT_X 1.0 1931cab2921ab279367f8206cdadc9259d12e603548Derek Sollenberger#define S_UNIT_Y 0.0 1941cab2921ab279367f8206cdadc9259d12e603548Derek Sollenberger#endif 1951cab2921ab279367f8206cdadc9259d12e603548Derek Sollenberger#endif 1961cab2921ab279367f8206cdadc9259d12e603548Derek Sollenberger 1971cab2921ab279367f8206cdadc9259d12e603548Derek Sollenberger/* Determine the polygon normal and project vertices onto the plane 1981cab2921ab279367f8206cdadc9259d12e603548Derek Sollenberger * of the polygon. 1991cab2921ab279367f8206cdadc9259d12e603548Derek Sollenberger */ 2001cab2921ab279367f8206cdadc9259d12e603548Derek Sollenbergervoid __gl_projectPolygon( GLUtesselator *tess ) 2011cab2921ab279367f8206cdadc9259d12e603548Derek Sollenberger{ 2021cab2921ab279367f8206cdadc9259d12e603548Derek Sollenberger GLUvertex *v, *vHead = &tess->mesh->vHead; 2031cab2921ab279367f8206cdadc9259d12e603548Derek Sollenberger GLdouble norm[3]; 2041cab2921ab279367f8206cdadc9259d12e603548Derek Sollenberger GLdouble *sUnit, *tUnit; 2051cab2921ab279367f8206cdadc9259d12e603548Derek Sollenberger int i, computedNormal = FALSE; 2061cab2921ab279367f8206cdadc9259d12e603548Derek Sollenberger 2071cab2921ab279367f8206cdadc9259d12e603548Derek Sollenberger norm[0] = tess->normal[0]; 2081cab2921ab279367f8206cdadc9259d12e603548Derek Sollenberger norm[1] = tess->normal[1]; 2091cab2921ab279367f8206cdadc9259d12e603548Derek Sollenberger norm[2] = tess->normal[2]; 2101cab2921ab279367f8206cdadc9259d12e603548Derek Sollenberger if( norm[0] == 0 && norm[1] == 0 && norm[2] == 0 ) { 2111cab2921ab279367f8206cdadc9259d12e603548Derek Sollenberger ComputeNormal( tess, norm ); 2121cab2921ab279367f8206cdadc9259d12e603548Derek Sollenberger computedNormal = TRUE; 2131cab2921ab279367f8206cdadc9259d12e603548Derek Sollenberger } 2141cab2921ab279367f8206cdadc9259d12e603548Derek Sollenberger sUnit = tess->sUnit; 2151cab2921ab279367f8206cdadc9259d12e603548Derek Sollenberger tUnit = tess->tUnit; 2161cab2921ab279367f8206cdadc9259d12e603548Derek Sollenberger i = LongAxis( norm ); 2171cab2921ab279367f8206cdadc9259d12e603548Derek Sollenberger 2181cab2921ab279367f8206cdadc9259d12e603548Derek Sollenberger#if defined(FOR_TRITE_TEST_PROGRAM) || defined(TRUE_PROJECT) 2191cab2921ab279367f8206cdadc9259d12e603548Derek Sollenberger /* Choose the initial sUnit vector to be approximately perpendicular 2201cab2921ab279367f8206cdadc9259d12e603548Derek Sollenberger * to the normal. 2211cab2921ab279367f8206cdadc9259d12e603548Derek Sollenberger */ 2221cab2921ab279367f8206cdadc9259d12e603548Derek Sollenberger Normalize( norm ); 2231cab2921ab279367f8206cdadc9259d12e603548Derek Sollenberger 2241cab2921ab279367f8206cdadc9259d12e603548Derek Sollenberger sUnit[i] = 0; 2251cab2921ab279367f8206cdadc9259d12e603548Derek Sollenberger sUnit[(i+1)%3] = S_UNIT_X; 2261cab2921ab279367f8206cdadc9259d12e603548Derek Sollenberger sUnit[(i+2)%3] = S_UNIT_Y; 2271cab2921ab279367f8206cdadc9259d12e603548Derek Sollenberger 2281cab2921ab279367f8206cdadc9259d12e603548Derek Sollenberger /* Now make it exactly perpendicular */ 2291cab2921ab279367f8206cdadc9259d12e603548Derek Sollenberger w = Dot( sUnit, norm ); 2301cab2921ab279367f8206cdadc9259d12e603548Derek Sollenberger sUnit[0] -= w * norm[0]; 2311cab2921ab279367f8206cdadc9259d12e603548Derek Sollenberger sUnit[1] -= w * norm[1]; 2321cab2921ab279367f8206cdadc9259d12e603548Derek Sollenberger sUnit[2] -= w * norm[2]; 2331cab2921ab279367f8206cdadc9259d12e603548Derek Sollenberger Normalize( sUnit ); 2341cab2921ab279367f8206cdadc9259d12e603548Derek Sollenberger 2351cab2921ab279367f8206cdadc9259d12e603548Derek Sollenberger /* Choose tUnit so that (sUnit,tUnit,norm) form a right-handed frame */ 2361cab2921ab279367f8206cdadc9259d12e603548Derek Sollenberger tUnit[0] = norm[1]*sUnit[2] - norm[2]*sUnit[1]; 2371cab2921ab279367f8206cdadc9259d12e603548Derek Sollenberger tUnit[1] = norm[2]*sUnit[0] - norm[0]*sUnit[2]; 2381cab2921ab279367f8206cdadc9259d12e603548Derek Sollenberger tUnit[2] = norm[0]*sUnit[1] - norm[1]*sUnit[0]; 2391cab2921ab279367f8206cdadc9259d12e603548Derek Sollenberger Normalize( tUnit ); 2401cab2921ab279367f8206cdadc9259d12e603548Derek Sollenberger#else 2411cab2921ab279367f8206cdadc9259d12e603548Derek Sollenberger /* Project perpendicular to a coordinate axis -- better numerically */ 2421cab2921ab279367f8206cdadc9259d12e603548Derek Sollenberger sUnit[i] = 0; 2431cab2921ab279367f8206cdadc9259d12e603548Derek Sollenberger sUnit[(i+1)%3] = S_UNIT_X; 2441cab2921ab279367f8206cdadc9259d12e603548Derek Sollenberger sUnit[(i+2)%3] = S_UNIT_Y; 2451cab2921ab279367f8206cdadc9259d12e603548Derek Sollenberger 2461cab2921ab279367f8206cdadc9259d12e603548Derek Sollenberger tUnit[i] = 0; 2471cab2921ab279367f8206cdadc9259d12e603548Derek Sollenberger tUnit[(i+1)%3] = (norm[i] > 0) ? -S_UNIT_Y : S_UNIT_Y; 2481cab2921ab279367f8206cdadc9259d12e603548Derek Sollenberger tUnit[(i+2)%3] = (norm[i] > 0) ? S_UNIT_X : -S_UNIT_X; 2491cab2921ab279367f8206cdadc9259d12e603548Derek Sollenberger#endif 2501cab2921ab279367f8206cdadc9259d12e603548Derek Sollenberger 2511cab2921ab279367f8206cdadc9259d12e603548Derek Sollenberger /* Project the vertices onto the sweep plane */ 2521cab2921ab279367f8206cdadc9259d12e603548Derek Sollenberger for( v = vHead->next; v != vHead; v = v->next ) { 2531cab2921ab279367f8206cdadc9259d12e603548Derek Sollenberger v->s = Dot( v->coords, sUnit ); 2541cab2921ab279367f8206cdadc9259d12e603548Derek Sollenberger v->t = Dot( v->coords, tUnit ); 2551cab2921ab279367f8206cdadc9259d12e603548Derek Sollenberger } 2561cab2921ab279367f8206cdadc9259d12e603548Derek Sollenberger if( computedNormal ) { 2571cab2921ab279367f8206cdadc9259d12e603548Derek Sollenberger CheckOrientation( tess ); 2581cab2921ab279367f8206cdadc9259d12e603548Derek Sollenberger } 2591cab2921ab279367f8206cdadc9259d12e603548Derek Sollenberger} 260