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+/*
+** License Applicability. Except to the extent portions of this file are
+** made subject to an alternative license as permitted in the SGI Free
+** Software License B, Version 1.1 (the "License"), the contents of this
+** file are subject only to the provisions of the License. You may not use
+** this file except in compliance with the License. You may obtain a copy
+** of the License at Silicon Graphics, Inc., attn: Legal Services, 1600
+** Amphitheatre Parkway, Mountain View, CA 94043-1351, or at:
+**
+** http://oss.sgi.com/projects/FreeB
+**
+** Note that, as provided in the License, the Software is distributed on an
+** "AS IS" basis, with ALL EXPRESS AND IMPLIED WARRANTIES AND CONDITIONS
+** DISCLAIMED, INCLUDING, WITHOUT LIMITATION, ANY IMPLIED WARRANTIES AND
+** CONDITIONS OF MERCHANTABILITY, SATISFACTORY QUALITY, FITNESS FOR A
+** PARTICULAR PURPOSE, AND NON-INFRINGEMENT.
+**
+** Original Code. The Original Code is: OpenGL Sample Implementation,
+** Version 1.2.1, released January 26, 2000, developed by Silicon Graphics,
+** Inc. The Original Code is Copyright (c) 1991-2000 Silicon Graphics, Inc.
+** Copyright in any portions created by third parties is as indicated
+** elsewhere herein. All Rights Reserved.
+**
+** Additional Notice Provisions: The application programming interfaces
+** established by SGI in conjunction with the Original Code are The
+** OpenGL(R) Graphics System: A Specification (Version 1.2.1), released
+** April 1, 1999; The OpenGL(R) Graphics System Utility Library (Version
+** 1.3), released November 4, 1998; and OpenGL(R) Graphics with the X
+** Window System(R) (Version 1.3), released October 19, 1998. This software
+** was created using the OpenGL(R) version 1.2.1 Sample Implementation
+** published by SGI, but has not been independently verified as being
+** compliant with the OpenGL(R) version 1.2.1 Specification.
+*/
+
+/*
+ * intersect.c++
+ *
+ */
+
+#include "glimports.h"
+#include "myassert.h"
+#include "mystdio.h"
+#include "subdivider.h"
+#include "arc.h"
+#include "bin.h"
+#include "backend.h"
+#include "trimvertpool.h"
+
+/*#define NOTDEF*/
+
+enum i_result { INTERSECT_VERTEX, INTERSECT_EDGE };
+
+/* local functions */
+#ifndef NDEBUG // for asserts only
+static int arc_classify( Arc_ptr, int, REAL );
+#endif
+static enum i_result pwlarc_intersect( PwlArc *, int, REAL, int, int[3] );
+
+
+void
+Subdivider::partition( Bin & bin, Bin & left, Bin & intersections,
+ Bin & right, Bin & unknown, int param, REAL value )
+{
+ Bin headonleft, headonright, tailonleft, tailonright;
+
+ for( Arc_ptr jarc = bin.removearc(); jarc; jarc = bin.removearc() ) {
+
+ REAL tdiff = jarc->tail()[param] - value;
+ REAL hdiff = jarc->head()[param] - value;
+
+ if( tdiff > 0.0 ) {
+ if( hdiff > 0.0 ) {
+ right.addarc( jarc );
+ } else if( hdiff == 0.0 ) {
+ tailonright.addarc( jarc );
+ } else {
+ Arc_ptr jtemp;
+ switch( arc_split(jarc, param, value, 0) ) {
+ case 2:
+ tailonright.addarc( jarc );
+ headonleft.addarc( jarc->next );
+ break;
+ case 31:
+ assert( jarc->head()[param] > value );
+ right.addarc( jarc );
+ tailonright.addarc( jtemp = jarc->next );
+ headonleft.addarc( jtemp->next );
+ break;
+ case 32:
+ assert( jarc->head()[param] <= value );
+ tailonright .addarc( jarc );
+ headonleft.addarc( jtemp = jarc->next );
+ left.addarc( jtemp->next );
+ break;
+ case 4:
+ right.addarc( jarc );
+ tailonright.addarc( jtemp = jarc->next );
+ headonleft.addarc( jtemp = jtemp->next );
+ left.addarc( jtemp->next );
+ }
+ }
+ } else if( tdiff == 0.0 ) {
+ if( hdiff > 0.0 ) {
+ headonright.addarc( jarc );
+ } else if( hdiff == 0.0 ) {
+ unknown.addarc( jarc );
+ } else {
+ headonleft.addarc( jarc );
+ }
+ } else {
+ if( hdiff > 0.0 ) {
+ Arc_ptr jtemp;
+ switch( arc_split(jarc, param, value, 1) ) {
+ case 2:
+ tailonleft.addarc( jarc );
+ headonright.addarc( jarc->next );
+ break;
+ case 31:
+ assert( jarc->head()[param] < value );
+ left.addarc( jarc );
+ tailonleft.addarc( jtemp = jarc->next );
+ headonright.addarc( jtemp->next );
+ break;
+ case 32:
+ assert( jarc->head()[param] >= value );
+ tailonleft.addarc( jarc );
+ headonright.addarc( jtemp = jarc->next );
+ right.addarc( jtemp->next );
+ break;
+ case 4:
+ left.addarc( jarc );
+ tailonleft.addarc( jtemp = jarc->next );
+ headonright.addarc( jtemp = jtemp->next );
+ right.addarc( jtemp->next );
+ }
+ } else if( hdiff == 0.0 ) {
+ tailonleft.addarc( jarc );
+ } else {
+ left.addarc( jarc );
+ }
+ }
+ }
+ if( param == 0 ) {
+ classify_headonleft_s( headonleft, intersections, left, value );
+ classify_tailonleft_s( tailonleft, intersections, left, value );
+ classify_headonright_s( headonright, intersections, right, value );
+ classify_tailonright_s( tailonright, intersections, right, value );
+ } else {
+ classify_headonleft_t( headonleft, intersections, left, value );
+ classify_tailonleft_t( tailonleft, intersections, left, value );
+ classify_headonright_t( headonright, intersections, right, value );
+ classify_tailonright_t( tailonright, intersections, right, value );
+ }
+}
+
+inline static void
+vert_interp( TrimVertex *n, TrimVertex *l, TrimVertex *r, int p, REAL val )
+{
+ assert( val > l->param[p]);
+ assert( val < r->param[p]);
+
+ n->nuid = l->nuid;
+
+ n->param[p] = val;
+ if( l->param[1-p] != r->param[1-p] ) {
+ REAL ratio = (val - l->param[p]) / (r->param[p] - l->param[p]);
+ n->param[1-p] = l->param[1-p] +
+ ratio * (r->param[1-p] - l->param[1-p]);
+ } else {
+ n->param[1-p] = l->param[1-p];
+ }
+}
+
+int
+Subdivider::arc_split( Arc_ptr jarc, int param, REAL value, int dir )
+{
+ int maxvertex = jarc->pwlArc->npts;
+ Arc_ptr jarc1;
+ TrimVertex* v = jarc->pwlArc->pts;
+
+ int loc[3];
+ switch( pwlarc_intersect( jarc->pwlArc, param, value, dir, loc ) ) {
+
+ // When the parameter value lands on a vertex, life is sweet
+ case INTERSECT_VERTEX: {
+ jarc1 = new(arcpool) Arc( jarc, new( pwlarcpool) PwlArc( maxvertex-loc[1], &v[loc[1]] ) );
+ jarc->pwlArc->npts = loc[1] + 1;
+ jarc1->next = jarc->next;
+ jarc1->next->prev = jarc1;
+ jarc->next = jarc1;
+ jarc1->prev = jarc;
+ assert(jarc->check() != 0);
+ return 2;
+ }
+
+ // When the parameter value intersects an edge, we have to
+ // interpolate a new vertex. There are special cases
+ // if the new vertex is adjacent to one or both of the
+ // endpoints of the arc.
+ case INTERSECT_EDGE: {
+ int i, j;
+ if( dir == 0 ) {
+ i = loc[0];
+ j = loc[2];
+ } else {
+ i = loc[2];
+ j = loc[0];
+ }
+
+#ifndef NOTDEF
+ // The split is between vertices at index j and i, in that
+ // order (j < i)
+
+ // JEB: This code is my idea of how to do the split without
+ // increasing the number of links. I'm doing this so that
+ // the is_rect routine can recognize rectangles created by
+ // subdivision. In exchange for simplifying the curve list,
+ // however, it costs in allocated space and vertex copies.
+
+ TrimVertex *newjunk = trimvertexpool.get(maxvertex -i+1 /*-j*/);
+ int k;
+ for(k=0; k<maxvertex-i; k++)
+ {
+ newjunk[k+1] = v[i+k];
+ newjunk[k+1].nuid = jarc->nuid;
+ }
+
+ TrimVertex *vcopy = trimvertexpool.get(maxvertex);
+ for(k=0; k<maxvertex; k++)
+ {
+ vcopy[k].param[0] = v[k].param[0];
+ vcopy[k].param[1] = v[k].param[1];
+ }
+ jarc->pwlArc->pts=vcopy;
+
+ v[i].nuid = jarc->nuid;
+ v[j].nuid = jarc->nuid;
+ vert_interp( &newjunk[0], &v[loc[0]], &v[loc[2]], param, value );
+
+ if( showingDegenerate() )
+ backend.triangle( &v[i], &newjunk[0], &v[j] );
+
+ vcopy[j+1].param[0]=newjunk[0].param[0];
+ vcopy[j+1].param[1]=newjunk[0].param[1];
+
+
+ jarc1 = new(arcpool) Arc( jarc,
+ new(pwlarcpool) PwlArc(maxvertex-i+1 , newjunk ) );
+
+ jarc->pwlArc->npts = j+2;
+ jarc1->next = jarc->next;
+ jarc1->next->prev = jarc1;
+ jarc->next = jarc1;
+ jarc1->prev = jarc;
+ assert(jarc->check() != 0);
+
+ return 2;
+#endif //not NOTDEF
+ // JEB: This is the original version:
+#ifdef NOTDEF
+ Arc_ptr jarc2, jarc3;
+
+ TrimVertex *newjunk = trimvertexpool.get(3);
+ v[i].nuid = jarc->nuid;
+ v[j].nuid = jarc->nuid;
+ newjunk[0] = v[j];
+ newjunk[2] = v[i];
+ vert_interp( &newjunk[1], &v[loc[0]], &v[loc[2]], param, value );
+
+ if( showingDegenerate() )
+ backend.triangle( &newjunk[2], &newjunk[1], &newjunk[0] );
+
+ // New vertex adjacent to both endpoints
+ if (maxvertex == 2) {
+ jarc1 = new(arcpool) Arc( jarc, new(pwlarcpool) PwlArc( 2, newjunk+1 ) );
+ jarc->pwlArc->npts = 2;
+ jarc->pwlArc->pts = newjunk;
+ jarc1->next = jarc->next;
+ jarc1->next->prev = jarc1;
+ jarc->next = jarc1;
+ jarc1->prev = jarc;
+ assert(jarc->check() != 0);
+
+ return 2;
+
+ // New vertex adjacent to ending point of arc
+ } else if (maxvertex - j == 2) {
+ jarc1 = new(arcpool) Arc( jarc, new(pwlarcpool) PwlArc( 2, newjunk ) );
+ jarc2 = new(arcpool) Arc( jarc, new(pwlarcpool) PwlArc( 2, newjunk+1 ) );
+ jarc->pwlArc->npts = maxvertex-1;
+ jarc2->next = jarc->next;
+ jarc2->next->prev = jarc2;
+ jarc->next = jarc1;
+ jarc1->prev = jarc;
+ jarc1->next = jarc2;
+ jarc2->prev = jarc1;
+ assert(jarc->check() != 0);
+ return 31;
+
+ // New vertex adjacent to starting point of arc
+ } else if (i == 1) {
+ jarc1 = new(arcpool) Arc( jarc, new(pwlarcpool) PwlArc( 2, newjunk+1 ) );
+ jarc2 = new(arcpool) Arc( jarc,
+ new(pwlarcpool) PwlArc( maxvertex-1, &jarc->pwlArc->pts[1] ) );
+ jarc->pwlArc->npts = 2;
+ jarc->pwlArc->pts = newjunk;
+ jarc2->next = jarc->next;
+ jarc2->next->prev = jarc2;
+ jarc->next = jarc1;
+ jarc1->prev = jarc;
+ jarc1->next = jarc2;
+ jarc2->prev = jarc1;
+ assert(jarc->check() != 0);
+ return 32;
+
+ // It's somewhere in the middle
+ } else {
+ jarc1 = new(arcpool) Arc( jarc, new(pwlarcpool) PwlArc( 2, newjunk ) );
+ jarc2 = new(arcpool) Arc( jarc, new(pwlarcpool) PwlArc( 2, newjunk+1 ) );
+ jarc3 = new(arcpool) Arc( jarc, new(pwlarcpool) PwlArc( maxvertex-i, v+i ) );
+ jarc->pwlArc->npts = j + 1;
+ jarc3->next = jarc->next;
+ jarc3->next->prev = jarc3;
+ jarc->next = jarc1;
+ jarc1->prev = jarc;
+ jarc1->next = jarc2;
+ jarc2->prev = jarc1;
+ jarc2->next = jarc3;
+ jarc3->prev = jarc2;
+ assert(jarc->check() != 0);
+ return 4;
+ }
+#endif // NOTDEF
+ }
+ default:
+ return -1; //picked -1 since it's not used
+ }
+}
+
+/*----------------------------------------------------------------------------
+ * pwlarc_intersect - find intersection of pwlArc and isoparametric line
+ *----------------------------------------------------------------------------
+ */
+
+static enum i_result
+pwlarc_intersect(
+ PwlArc *pwlArc,
+ int param,
+ REAL value,
+ int dir,
+ int loc[3] )
+{
+ assert( pwlArc->npts > 0 );
+
+ if( dir ) {
+ TrimVertex *v = pwlArc->pts;
+ int imin = 0;
+ int imax = pwlArc->npts - 1;
+ assert( value > v[imin].param[param] );
+ assert( value < v[imax].param[param] );
+ while( (imax - imin) > 1 ) {
+ int imid = (imax + imin)/2;
+ if( v[imid].param[param] > value )
+ imax = imid;
+ else if( v[imid].param[param] < value )
+ imin = imid;
+ else {
+ loc[1] = imid;
+ return INTERSECT_VERTEX;
+ }
+ }
+ loc[0] = imin;
+ loc[2] = imax;
+ return INTERSECT_EDGE;
+ } else {
+ TrimVertex *v = pwlArc->pts;
+ int imax = 0;
+ int imin = pwlArc->npts - 1;
+ assert( value > v[imin].param[param] );
+ assert( value < v[imax].param[param] );
+ while( (imin - imax) > 1 ) {
+ int imid = (imax + imin)/2;
+ if( v[imid].param[param] > value )
+ imax = imid;
+ else if( v[imid].param[param] < value )
+ imin = imid;
+ else {
+ loc[1] = imid;
+ return INTERSECT_VERTEX;
+ }
+ }
+ loc[0] = imin;
+ loc[2] = imax;
+ return INTERSECT_EDGE;
+ }
+}
+
+/*----------------------------------------------------------------------------
+ * arc_classify - determine which side of a line a jarc lies
+ *----------------------------------------------------------------------------
+ */
+
+#ifndef NDEBUG // for asserts only
+static int
+arc_classify( Arc_ptr jarc, int param, REAL value )
+{
+ REAL tdiff, hdiff;
+ if( param == 0 ) {
+ tdiff = jarc->tail()[0] - value;
+ hdiff = jarc->head()[0] - value;
+ } else {
+ tdiff = jarc->tail()[1] - value;
+ hdiff = jarc->head()[1] - value;
+ }
+
+ if( tdiff > 0.0 ) {
+ if( hdiff > 0.0 ) {
+ return 0x11;
+ } else if( hdiff == 0.0 ) {
+ return 0x12;
+ } else {
+ return 0x10;
+ }
+ } else if( tdiff == 0.0 ) {
+ if( hdiff > 0.0 ) {
+ return 0x21;
+ } else if( hdiff == 0.0 ) {
+ return 0x22;
+ } else {
+ return 0x20;
+ }
+ } else {
+ if( hdiff > 0.0 ) {
+ return 0x01;
+ } else if( hdiff == 0.0 ) {
+ return 0x02;
+ } else {
+ return 0;
+ }
+ }
+}
+#endif
+
+void
+Subdivider::classify_tailonleft_s( Bin& bin, Bin& in, Bin& out, REAL val )
+{
+ /* tail at left, head on line */
+ Arc_ptr j;
+
+ while( (j = bin.removearc()) != NULL ) {
+ assert( arc_classify( j, 0, val ) == 0x02 );
+ j->clearitail();
+
+ REAL diff = j->next->head()[0] - val;
+ if( diff > 0.0 ) {
+ in.addarc( j );
+ } else if( diff < 0.0 ) {
+ if( ccwTurn_sl( j, j->next ) )
+ out.addarc( j );
+ else
+ in.addarc( j );
+ } else {
+ if( j->next->tail()[1] > j->next->head()[1] )
+ in.addarc(j);
+ else
+ out.addarc(j);
+ }
+ }
+}
+
+void
+Subdivider::classify_tailonleft_t( Bin& bin, Bin& in, Bin& out, REAL val )
+{
+ /* tail at left, head on line */
+ Arc_ptr j;
+
+ while( (j = bin.removearc()) != NULL ) {
+ assert( arc_classify( j, 1, val ) == 0x02 );
+ j->clearitail();
+
+ REAL diff = j->next->head()[1] - val;
+ if( diff > 0.0 ) {
+ in.addarc( j );
+ } else if( diff < 0.0 ) {
+ if( ccwTurn_tl( j, j->next ) )
+ out.addarc( j );
+ else
+ in.addarc( j );
+ } else {
+ if (j->next->tail()[0] > j->next->head()[0] )
+ out.addarc( j );
+ else
+ in.addarc( j );
+ }
+ }
+}
+
+void
+Subdivider::classify_headonleft_s( Bin& bin, Bin& in, Bin& out, REAL val )
+{
+ /* tail on line, head at left */
+ Arc_ptr j;
+
+ while( (j = bin.removearc()) != NULL ) {
+ assert( arc_classify( j, 0, val ) == 0x20 );
+
+ j->setitail();
+
+ REAL diff = j->prev->tail()[0] - val;
+ if( diff > 0.0 ) {
+ out.addarc( j );
+ } else if( diff < 0.0 ) {
+ if( ccwTurn_sl( j->prev, j ) )
+ out.addarc( j );
+ else
+ in.addarc( j );
+ } else {
+ if( j->prev->tail()[1] > j->prev->head()[1] )
+ in.addarc( j );
+ else
+ out.addarc( j );
+ }
+ }
+}
+
+void
+Subdivider::classify_headonleft_t( Bin& bin, Bin& in, Bin& out, REAL val )
+{
+ /* tail on line, head at left */
+ Arc_ptr j;
+
+ while( (j = bin.removearc()) != NULL ) {
+ assert( arc_classify( j, 1, val ) == 0x20 );
+ j->setitail();
+
+ REAL diff = j->prev->tail()[1] - val;
+ if( diff > 0.0 ) {
+ out.addarc( j );
+ } else if( diff < 0.0 ) {
+ if( ccwTurn_tl( j->prev, j ) )
+ out.addarc( j );
+ else
+ in.addarc( j );
+ } else {
+ if( j->prev->tail()[0] > j->prev->head()[0] )
+ out.addarc( j );
+ else
+ in.addarc( j );
+ }
+ }
+}
+
+
+void
+Subdivider::classify_tailonright_s( Bin& bin, Bin& in, Bin& out, REAL val )
+{
+ /* tail at right, head on line */
+ Arc_ptr j;
+
+ while( (j = bin.removearc()) != NULL ) {
+ assert( arc_classify( j, 0, val ) == 0x12);
+
+ j->clearitail();
+
+ REAL diff = j->next->head()[0] - val;
+ if( diff > 0.0 ) {
+ if( ccwTurn_sr( j, j->next ) )
+ out.addarc( j );
+ else
+ in.addarc( j );
+ } else if( diff < 0.0 ) {
+ in.addarc( j );
+ } else {
+ if( j->next->tail()[1] > j->next->head()[1] )
+ out.addarc( j );
+ else
+ in.addarc( j );
+ }
+ }
+}
+
+void
+Subdivider::classify_tailonright_t( Bin& bin, Bin& in, Bin& out, REAL val )
+{
+ /* tail at right, head on line */
+ Arc_ptr j;
+
+ while( (j = bin.removearc()) != NULL ) {
+ assert( arc_classify( j, 1, val ) == 0x12);
+
+ j->clearitail();
+
+ REAL diff = j->next->head()[1] - val;
+ if( diff > 0.0 ) {
+ if( ccwTurn_tr( j, j->next ) )
+ out.addarc( j );
+ else
+ in.addarc( j );
+ } else if( diff < 0.0 ) {
+ in.addarc( j );
+ } else {
+ if( j->next->tail()[0] > j->next->head()[0] )
+ in.addarc( j );
+ else
+ out.addarc( j );
+ }
+ }
+}
+
+void
+Subdivider::classify_headonright_s( Bin& bin, Bin& in, Bin& out, REAL val )
+{
+ /* tail on line, head at right */
+ Arc_ptr j;
+
+ while( (j = bin.removearc()) != NULL ) {
+ assert( arc_classify( j, 0, val ) == 0x21 );
+
+ j->setitail();
+
+ REAL diff = j->prev->tail()[0] - val;
+ if( diff > 0.0 ) {
+ if( ccwTurn_sr( j->prev, j ) )
+ out.addarc( j );
+ else
+ in.addarc( j );
+ } else if( diff < 0.0 ) {
+ out.addarc( j );
+ } else {
+ if( j->prev->tail()[1] > j->prev->head()[1] )
+ out.addarc( j );
+ else
+ in.addarc( j );
+ }
+ }
+}
+
+void
+Subdivider::classify_headonright_t( Bin& bin, Bin& in, Bin& out, REAL val )
+{
+ /* tail on line, head at right */
+ Arc_ptr j;
+
+ while( (j = bin.removearc()) != NULL ) {
+ assert( arc_classify( j, 1, val ) == 0x21 );
+
+ j->setitail();
+
+ REAL diff = j->prev->tail()[1] - val;
+ if( diff > 0.0 ) {
+ if( ccwTurn_tr( j->prev, j ) )
+ out.addarc( j );
+ else
+ in.addarc( j );
+ } else if( diff < 0.0 ) {
+ out.addarc( j );
+ } else {
+ if( j->prev->tail()[0] > j->prev->head()[0] )
+ in.addarc( j );
+ else
+ out.addarc( j );
+ }
+ }
+}
+
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