intersect.cc

Mesa is an open-source implementation of the OpenGL specification - a system for rendering interacti

/*
** 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++
 *
 * $Date: 2005/10/28 13:09:23 $ $Revision: 1.3 $
 * $Header: /home/krh/git/sync/mesa-cvs-repo/Mesa/src/glu/sgi/libnurbs/internals/intersect.cc,v 1.3 2005/10/28 13:09:23 brianp Exp $
 */

#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;
	    }