patch.cc

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

 * 		and determine if patch needs to be subdivided
 *--------------------------------------------------------------------------
 */

void
Patch::getstepsize( void )
{
    pspec[0].minstepsize = pspec[1].minstepsize = 0;
    pspec[0].needsSubdivision = pspec[1].needsSubdivision = 0;

    if( mapdesc->isConstantSampling() ) {
	// fixed number of samples per patch in each direction
	// maxsrate is number of s samples per patch
	// maxtrate is number of t samples per patch
        pspec[0].getstepsize( mapdesc->maxsrate );
        pspec[1].getstepsize( mapdesc->maxtrate );

    } else if( mapdesc->isDomainSampling() ) {
	// maxsrate is number of s samples per unit s length of domain
	// maxtrate is number of t samples per unit t length of domain
        pspec[0].getstepsize( mapdesc->maxsrate * pspec[0].range[2] );
        pspec[1].getstepsize( mapdesc->maxtrate * pspec[1].range[2] );

    } else if( ! needsSampling ) {
	pspec[0].singleStep();
	pspec[1].singleStep();
    } else {
	// upper bound on path length between sample points
        REAL tmp[MAXORDER][MAXORDER][MAXCOORDS];
	const int trstride = sizeof(tmp[0]) / sizeof(REAL);
	const int tcstride = sizeof(tmp[0][0]) / sizeof(REAL); 

	assert( pspec[0].order <= MAXORDER );
    
	/* points have been transformed, therefore they are homogeneous */

	int val = mapdesc->project( spts, pspec[0].stride, pspec[1].stride, 
		 &tmp[0][0][0], trstride, tcstride, 
		 pspec[0].order, pspec[1].order ); 
        if( val == 0 ) {
	    // control points cross infinity, therefore partials are undefined
            pspec[0].getstepsize( mapdesc->maxsrate );
            pspec[1].getstepsize( mapdesc->maxtrate );
        } else {
            REAL t1 = mapdesc->getProperty( N_PIXEL_TOLERANCE );
//	    REAL t2 = mapdesc->getProperty( N_ERROR_TOLERANCE );
	    pspec[0].minstepsize = ( mapdesc->maxsrate > 0.0 ) ? 
			(pspec[0].range[2] / mapdesc->maxsrate) : 0.0;
	    pspec[1].minstepsize = ( mapdesc->maxtrate > 0.0 ) ? 
			(pspec[1].range[2] / mapdesc->maxtrate) : 0.0;
	    if( mapdesc->isParametricDistanceSampling() ||
                mapdesc->isObjectSpaceParaSampling() ) {       

                REAL t2;
                t2 = mapdesc->getProperty( N_ERROR_TOLERANCE );
		
		// t2 is upper bound on the distance between surface and tessellant 
		REAL ssv[2], ttv[2];
		REAL ss = mapdesc->calcPartialVelocity( ssv, &tmp[0][0][0], trstride, tcstride, pspec[0].order, pspec[1].order, 2, 0, pspec[0].range[2], pspec[1].range[2], 0 );
		REAL st = mapdesc->calcPartialVelocity(   0, &tmp[0][0][0], trstride, tcstride, pspec[0].order, pspec[1].order, 1, 1, pspec[0].range[2], pspec[1].range[2], -1 );
		REAL tt = mapdesc->calcPartialVelocity( ttv, &tmp[0][0][0], trstride, tcstride, pspec[0].order, pspec[1].order, 0, 2, pspec[0].range[2], pspec[1].range[2], 1 );
	        //make sure that ss st and tt are nonnegative:
 	        if(ss <0) ss = -ss;
	        if(st <0) st = -st;
                if(tt <0) tt = -tt;

		if( ss != 0.0 && tt != 0.0 ) {
		    /* printf( "ssv[0] %g ssv[1] %g ttv[0] %g ttv[1] %g\n", 
			ssv[0], ssv[1], ttv[0], ttv[1] ); */
		    REAL ttq = sqrtf( (float) ss );
		    REAL ssq = sqrtf( (float) tt );
		    REAL ds = sqrtf( 4 * t2 * ttq / ( ss * ttq + st * ssq ) );
		    REAL dt = sqrtf( 4 * t2 * ssq / ( tt * ssq + st * ttq ) );
		    pspec[0].stepsize = ( ds < pspec[0].range[2] ) ? ds : pspec[0].range[2];
		    REAL scutoff = 2.0 * t2 / ( pspec[0].range[2] * pspec[0].range[2]);
		    pspec[0].sidestep[0] = (ssv[0] > scutoff) ? sqrtf( 2.0 * t2 / ssv[0] ) : pspec[0].range[2];
		    pspec[0].sidestep[1] = (ssv[1] > scutoff) ? sqrtf( 2.0 * t2 / ssv[1] ) : pspec[0].range[2];
    
		    pspec[1].stepsize = ( dt < pspec[1].range[2] ) ? dt : pspec[1].range[2];
		    REAL tcutoff = 2.0 * t2 / ( pspec[1].range[2] * pspec[1].range[2]);
		    pspec[1].sidestep[0] = (ttv[0] > tcutoff) ? sqrtf( 2.0 * t2 / ttv[0] ) : pspec[1].range[2];
		    pspec[1].sidestep[1] = (ttv[1] > tcutoff) ? sqrtf( 2.0 * t2 / ttv[1] ) : pspec[1].range[2];
		} else if( ss != 0.0 ) {
		    REAL x = pspec[1].range[2] * st;
		    REAL ds = ( sqrtf( x * x + 8.0 * t2 * ss ) - x ) / ss;
		    pspec[0].stepsize = ( ds < pspec[0].range[2] ) ? ds : pspec[0].range[2];
		    REAL scutoff = 2.0 * t2 / ( pspec[0].range[2] * pspec[0].range[2]);
		    pspec[0].sidestep[0] = (ssv[0] > scutoff) ? sqrtf( 2.0 * t2 / ssv[0] ) : pspec[0].range[2];
		    pspec[0].sidestep[1] = (ssv[1] > scutoff) ? sqrtf( 2.0 * t2 / ssv[1] ) : pspec[0].range[2];
		    pspec[1].singleStep();
		} else if( tt != 0.0 ) {
		    REAL x = pspec[0].range[2] * st;
		    REAL dt = ( sqrtf( x * x + 8.0 * t2 * tt ) - x )  / tt;
		    pspec[0].singleStep();
		    REAL tcutoff = 2.0 * t2 / ( pspec[1].range[2] * pspec[1].range[2]);
		    pspec[1].stepsize = ( dt < pspec[1].range[2] ) ? dt : pspec[1].range[2];
		    pspec[1].sidestep[0] = (ttv[0] > tcutoff) ? sqrtf( 2.0 * t2 / ttv[0] ) : pspec[1].range[2];
		    pspec[1].sidestep[1] = (ttv[1] > tcutoff) ? sqrtf( 2.0 * t2 / ttv[1] ) : pspec[1].range[2];
		} else {
		    if( 4.0 * t2  > st * pspec[0].range[2] * pspec[1].range[2] ) {
			pspec[0].singleStep();
			pspec[1].singleStep();
		    } else {
			REAL area = 4.0 * t2 / st;
			REAL ds = sqrtf( area * pspec[0].range[2] / pspec[1].range[2] );
			REAL dt = sqrtf( area * pspec[1].range[2] / pspec[0].range[2] );
			pspec[0].stepsize = ( ds < pspec[0].range[2] ) ? ds : pspec[0].range[2];
			pspec[0].sidestep[0] = pspec[0].range[2];
			pspec[0].sidestep[1] = pspec[0].range[2];
	
			pspec[1].stepsize = ( dt < pspec[1].range[2] ) ? dt : pspec[1].range[2];
			pspec[1].sidestep[0] = pspec[1].range[2];
			pspec[1].sidestep[1] = pspec[1].range[2];
		    }
		}	
	    } else if( mapdesc->isPathLengthSampling() ||
		      mapdesc->isObjectSpacePathSampling()) {
		// t1 is upper bound on path length
		REAL msv[2], mtv[2];
		REAL ms = mapdesc->calcPartialVelocity( msv, &tmp[0][0][0], trstride, tcstride, pspec[0].order, pspec[1].order, 1, 0, pspec[0].range[2], pspec[1].range[2], 0 );
		REAL mt = mapdesc->calcPartialVelocity( mtv, &tmp[0][0][0], trstride, tcstride, pspec[0].order, pspec[1].order, 0, 1, pspec[0].range[2], pspec[1].range[2], 1 );
                REAL side_scale = 1.0;

		if( ms != 0.0 ) {
		    if( mt != 0.0 ) {
/*		    REAL d = t1 / ( ms * ms + mt * mt );*/
/*		    REAL ds = mt * d;*/
		    REAL ds = t1 / (2.0*ms);
/*		    REAL dt = ms * d;*/
		    REAL dt = t1 / (2.0*mt); 
			pspec[0].stepsize = ( ds < pspec[0].range[2] ) ? ds : pspec[0].range[2];
			pspec[0].sidestep[0] = ( msv[0] * pspec[0].range[2] > t1 ) ? (side_scale* t1 / msv[0]) : pspec[0].range[2];
			pspec[0].sidestep[1] = ( msv[1] * pspec[0].range[2] > t1 ) ? (side_scale* t1 / msv[1]) : pspec[0].range[2];
	
			pspec[1].stepsize = ( dt < pspec[1].range[2] ) ? dt : pspec[1].range[2];
			pspec[1].sidestep[0] = ( mtv[0] * pspec[1].range[2] > t1 ) ? (side_scale*t1 / mtv[0]) : pspec[1].range[2];
			pspec[1].sidestep[1] = ( mtv[1] * pspec[1].range[2] > t1 ) ? (side_scale*t1 / mtv[1]) : pspec[1].range[2];
		    } else {
			pspec[0].stepsize = ( t1 < ms * pspec[0].range[2] ) ? (t1 / ms) : pspec[0].range[2];
			pspec[0].sidestep[0] = ( msv[0] * pspec[0].range[2] > t1 ) ? (t1 / msv[0]) : pspec[0].range[2];
			pspec[0].sidestep[1] = ( msv[1] * pspec[0].range[2] > t1 ) ? (t1 / msv[1]) : pspec[0].range[2];
	
			pspec[1].singleStep();
		    }
		} else {
		    if( mt != 0.0 ) {
			pspec[0].singleStep();

			pspec[1].stepsize = ( t1 < mt * pspec[1].range[2] ) ? (t1 / mt) : pspec[1].range[2];
			pspec[1].sidestep[0] = ( mtv[0] * pspec[1].range[2] > t1 ) ? (t1 / mtv[0]) : pspec[1].range[2];
			pspec[1].sidestep[1] = ( mtv[1] * pspec[1].range[2] > t1 ) ? (t1 / mtv[1]) : pspec[1].range[2];
		    } else {
			pspec[0].singleStep();
			pspec[1].singleStep();
		    }
		}
	    } else if( mapdesc->isSurfaceAreaSampling() ) {
		// t is the square root of area
/*
		REAL msv[2], mtv[2];
		REAL ms = mapdesc->calcPartialVelocity( msv, &tmp[0][0][0], trstride, tcstride, pspec[0].order, pspec[1].order, 1, 0, pspec[0].range[2], pspec[1].range[2], 0 );
		REAL mt = mapdesc->calcPartialVelocity( mtv, &tmp[0][0][0], trstride, tcstride, pspec[0].order, pspec[1].order, 0, 1, pspec[0].range[2], pspec[1].range[2], 1 );
		if( ms != 0.0 &&  mt != 0.0 ) {
			REAL d = 1.0 / (ms * mt);
			t *= M_SQRT2;
			REAL ds = t * sqrtf( d * pspec[0].range[2] / pspec[1].range[2] );
			REAL dt = t * sqrtf( d * pspec[1].range[2] / pspec[0].range[2] );
			pspec[0].stepsize = ( ds < pspec[0].range[2] ) ? ds : pspec[0].range[2];
			pspec[0].sidestep[0] = ( msv[0] * pspec[0].range[2] > t ) ? (t / msv[0]) : pspec[0].range[2];
			pspec[0].sidestep[1] = ( msv[1] * pspec[0].range[2] > t ) ? (t / msv[1]) : pspec[0].range[2];
	
			pspec[1].stepsize = ( dt < pspec[1].range[2] ) ? dt : pspec[1].range[2];
			pspec[1].sidestep[0] = ( mtv[0] * pspec[1].range[2] > t ) ? (t / mtv[0]) : pspec[1].range[2];
			pspec[1].sidestep[1] = ( mtv[1] * pspec[1].range[2] > t ) ? (t / mtv[1]) : pspec[1].range[2];
		} else {
		    pspec[0].singleStep();
		    pspec[1].singleStep();
		}
*/
	    } else {
		pspec[0].singleStep();
		pspec[1].singleStep();
	    }
	}
    }

#ifdef DEBUG
    _glu_dprintf( "sidesteps %g %g %g %g, stepsize %g %g\n",
	pspec[0].sidestep[0], pspec[0].sidestep[1],
	pspec[1].sidestep[0], pspec[1].sidestep[1],
	pspec[0].stepsize, pspec[1].stepsize );
#endif

    if( mapdesc->minsavings != N_NOSAVINGSSUBDIVISION ) {
	REAL savings = 1./(pspec[0].stepsize * pspec[1].stepsize) ;
	savings-= (2./( pspec[0].sidestep[0] + pspec[0].sidestep[1] )) * 
		  (2./( pspec[1].sidestep[0] + pspec[1].sidestep[1] ));
    
	savings *= pspec[0].range[2] * pspec[1].range[2];
	if( savings > mapdesc->minsavings ) {
	    pspec[0].needsSubdivision = pspec[1].needsSubdivision = 1;
	}
    }

    if( pspec[0].stepsize < pspec[0].minstepsize )  pspec[0].needsSubdivision =  1;
    if( pspec[1].stepsize < pspec[1].minstepsize )  pspec[1].needsSubdivision =  1;
    needsSampling = (needsSampling ? needsSamplingSubdivision() : 0);
}

void
Patchspec::singleStep()
{
    stepsize =  sidestep[0] =  sidestep[1] = glu_abs(range[2]);
}

void 
Patchspec::getstepsize( REAL max ) // max is number of samples for entire patch
{
    stepsize = ( max >= 1.0 ) ? range[2] / max : range[2];
    if (stepsize < 0.0) {
       stepsize = -stepsize;
    }
    sidestep[0]	=  sidestep[1] = minstepsize = stepsize;
}

int
Patch::needsSamplingSubdivision( void )
{
    return (pspec[0].needsSubdivision || pspec[1].needsSubdivision) ? 1 : 0;
}

int
Patch::needsNonSamplingSubdivision( void )
{
    return notInBbox;
}

int
Patch::needsSubdivision( int param )
{
    return pspec[param].needsSubdivision;
}

int
Patch::cullCheck( void )
{
    if( cullval == CULL_ACCEPT ) 
	cullval = mapdesc->cullCheck( cpts, pspec[0].order,  pspec[0].stride,
					    pspec[1].order,  pspec[1].stride );
    return cullval;
}