arctess.cc

winNT技术操作系统,国外开放的原代码和LIUX一样

/*
** 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.
*/

/*
 * arctessellator.c++
 *
 */

#include "glimports.h"
#include "mystdio.h"
#include "myassert.h"
#include "arctess.h"
#include "bufpool.h"
#include "simplemath.h"
#include "bezierarc.h"
#include "trimvertex.h"
#include "trimvertpool.h"

#define NOELIMINATION

#define steps_function(large, small, rate) (max(1, 1+ (int) ((large-small)/rate)));

/*-----------------------------------------------------------------------------
 * ArcTessellator - construct an ArcTessellator
 *-----------------------------------------------------------------------------
 */

ArcTessellator::ArcTessellator( TrimVertexPool& t, Pool& p ) 
	: pwlarcpool(p), trimvertexpool(t)
{
}

/*-----------------------------------------------------------------------------
 * ~ArcTessellator - destroy an ArcTessellator
 *-----------------------------------------------------------------------------
 */

ArcTessellator::~ArcTessellator( void )
{
}

/*-----------------------------------------------------------------------------
 * bezier - construct a bezier arc and attach it to an Arc
 *-----------------------------------------------------------------------------
 */

void
ArcTessellator::bezier( Arc *arc, REAL s1, REAL s2, REAL t1, REAL t2 )
{
    assert( arc != 0 );
    assert( ! arc->isTessellated() );

#ifndef NDEBUG
    switch( arc->getside() ) {
	case arc_left:
	    assert( s1 == s2 );
	    assert( t2 < t1 );
	    break;
	case arc_right:
	    assert( s1 == s2 );
	    assert( t1 < t2 );
	    break;
	case arc_top:
	    assert( t1 == t2 );
	    assert( s2 < s1 );
	    break;
	case arc_bottom:
	    assert( t1 == t2 );
	    assert( s1 < s2 );
	    break;
	case arc_none:
	    (void) abort();
	    break;
    }
#endif
    
    TrimVertex *p = trimvertexpool.get(2);
    arc->pwlArc = new(pwlarcpool) PwlArc( 2, p );
    p[0].param[0] = s1;
    p[0].param[1] = t1;
    p[1].param[0] = s2;
    p[1].param[1] = t2;
    assert( (s1 == s2) || (t1 == t2) );
    arc->setbezier();
}


/*-----------------------------------------------------------------------------
 * pwl_left - construct a left boundary pwl arc and attach it to an arc
 *-----------------------------------------------------------------------------
 */

void
ArcTessellator::pwl_left( Arc *arc, REAL s, REAL t1, REAL t2, REAL rate )
{
    assert( t2 < t1 );

/*    if(rate <= 0.06) rate = 0.06;*/
/*    int nsteps = 1 + (int) ((t1 - t2) / rate ); */
    int nsteps = steps_function(t1, t2, rate);


    REAL stepsize = (t1 - t2) / (REAL) nsteps;

    TrimVertex *newvert = trimvertexpool.get( nsteps+1 );
    int i;
    for( i = nsteps; i > 0; i-- ) {
	newvert[i].param[0] = s;
	newvert[i].param[1] = t2;
	t2 += stepsize;
    }
    newvert[i].param[0] = s;
    newvert[i].param[1] = t1;

    arc->makeSide( new(pwlarcpool) PwlArc( nsteps+1, newvert ), arc_left );
}

/*-----------------------------------------------------------------------------
 * pwl_right - construct a right boundary pwl arc and attach it to an arc
 *-----------------------------------------------------------------------------
 */

void
ArcTessellator::pwl_right( Arc *arc, REAL s, REAL t1, REAL t2, REAL rate )
{
    assert( t1 < t2 );

/*    if(rate <= 0.06) rate = 0.06;*/

/*    int nsteps = 1 + (int) ((t2 - t1) / rate ); */
    int nsteps = steps_function(t2,t1,rate);
    REAL stepsize = (t2 - t1) / (REAL) nsteps;

    TrimVertex *newvert = trimvertexpool.get( nsteps+1 );
    int i;
    for( i = 0; i < nsteps; i++ ) {
	newvert[i].param[0] = s;
	newvert[i].param[1] = t1;
	t1 += stepsize;
    }
    newvert[i].param[0] = s;
    newvert[i].param[1] = t2;

    arc->makeSide( new(pwlarcpool) PwlArc( nsteps+1, newvert ), arc_right );
}


/*-----------------------------------------------------------------------------
 * pwl_top - construct a top boundary pwl arc and attach it to an arc
 *-----------------------------------------------------------------------------
 */

void
ArcTessellator::pwl_top( Arc *arc, REAL t, REAL s1, REAL s2, REAL rate )
{
    assert( s2 < s1 );

/*    if(rate <= 0.06) rate = 0.06;*/

/*    int nsteps = 1 + (int) ((s1 - s2) / rate ); */
    int nsteps = steps_function(s1,s2,rate);
    REAL stepsize = (s1 - s2) / (REAL) nsteps;

    TrimVertex *newvert = trimvertexpool.get( nsteps+1 );
    int i;
    for( i = nsteps; i > 0; i-- ) {
	newvert[i].param[0] = s2;
	newvert[i].param[1] = t;
	s2 += stepsize;
    }
    newvert[i].param[0] = s1;
    newvert[i].param[1] = t;

    arc->makeSide( new(pwlarcpool) PwlArc( nsteps+1, newvert ), arc_top );
}

/*-----------------------------------------------------------------------------
 * pwl_bottom - construct a bottom boundary pwl arc and attach it to an arc
 *-----------------------------------------------------------------------------
 */

void
ArcTessellator::pwl_bottom( Arc *arc, REAL t, REAL s1, REAL s2, REAL rate )
{
    assert( s1 < s2 );

/*    if(rate <= 0.06) rate = 0.06;*/

/*    int nsteps = 1 + (int) ((s2 - s1) / rate ); */
    int nsteps = steps_function(s2,s1,rate);
    REAL stepsize = (s2 - s1) / (REAL) nsteps;

    TrimVertex *newvert = trimvertexpool.get( nsteps+1 );
    int i;
    for( i = 0; i < nsteps; i++ ) {
	newvert[i].param[0] = s1;
	newvert[i].param[1] = t;
	s1 += stepsize;
    }
    newvert[i].param[0] = s2;
    newvert[i].param[1] = t;

    arc->makeSide( new(pwlarcpool) PwlArc( nsteps+1, newvert ), arc_bottom );
}

/*-----------------------------------------------------------------------------
 * pwl - construct a pwl arc and attach it to an arc
 *-----------------------------------------------------------------------------
 */

void
ArcTessellator::pwl( Arc *arc, REAL s1, REAL s2, REAL t1, REAL t2, REAL rate )
{

/*    if(rate <= 0.06) rate = 0.06;*/

    int snsteps = 1 + (int) (glu_abs(s2 - s1) / rate );
    int tnsteps = 1 + (int) (glu_abs(t2 - t1) / rate );
    int nsteps = max(1,max( snsteps, tnsteps ));

    REAL sstepsize = (s2 - s1) / (REAL) nsteps;
    REAL tstepsize = (t2 - t1) / (REAL) nsteps;
    TrimVertex *newvert = trimvertexpool.get( nsteps+1 );
    long i;
    for( i = 0; i < nsteps; i++ ) {
	newvert[i].param[0] = s1;
	newvert[i].param[1] = t1;
	s1 += sstepsize;
	t1 += tstepsize;
    }
    newvert[i].param[0] = s2;
    newvert[i].param[1] = t2;

    /* arc->makeSide( new(pwlarcpool) PwlArc( nsteps+1, newvert ), arc_bottom ); */
    arc->pwlArc = new(pwlarcpool) PwlArc( nsteps+1, newvert );

    arc->clearbezier();
    arc->clearside( );
}


/*-----------------------------------------------------------------------------
 * tessellateLinear - constuct a linear pwl arc and attach it to an Arc
 *-----------------------------------------------------------------------------
 */

void
ArcTessellator::tessellateLinear( Arc *arc, REAL geo_stepsize, REAL arc_stepsize, int isrational )
{
    assert( arc->pwlArc == NULL );
    REAL s1, s2, t1, t2;

    //we don't need to scale by arc_stepsize if the trim curve
    //is piecewise linear. Reason: In pwl_right, pwl_left, pwl_top, pwl_left,
    //and pwl, the nsteps is computed by deltaU (or V) /stepsize. 
    //The quantity deltaU/arc_stepsize doesn't have any meaning. And
    //it causes problems: see bug 517641
    REAL stepsize = geo_stepsize; /* * arc_stepsize*/;

    BezierArc *b = arc->bezierArc;

    if( isrational ) {
	s1 = b->cpts[0] / b->cpts[2];
	t1 = b->cpts[1] / b->cpts[2];
	s2 = b->cpts[b->stride+0] / b->cpts[b->stride+2];
	t2 = b->cpts[b->stride+1] / b->cpts[b->stride+2];
    } else {
	s1 = b->cpts[0];
	t1 = b->cpts[1];
	s2 = b->cpts[b->stride+0];
	t2 = b->cpts[b->stride+1];
    }