#
# Silhouette test,  Gershon Elber 2002
#

save_res = resolution;

#############################################################################

SphDirs = list(
    point(  0.190702792257, -0.981542113237,  0.014405687340 ),
    point( -0.262428475544, -0.649809330702, -0.713357643224 ),
    point( -0.757185248658, -0.608582364395,  0.237272003666 ),
    point( -0.426304692402, -0.610978642479,  0.667060271837 ),
    point( -0.189071986824, -0.218912631273,  0.957250772975 ),
    point(  0.182211644948, -0.480793872848, -0.857692349702 ),
    point(  0.634234739468, -0.476225292310, -0.609061378986 ),
    point(  0.138573494740, -0.549335450865,  0.824031520635 ),
    point( -0.850272424519,  0.111690244637, -0.514355996624 ),
    point(  0.936054584570, -0.269206611440, -0.226560398005 ),
    point(  0.492522636428, -0.774523432367,  0.396906669252 ),
    point(  0.788703111932,  0.550208870322,  0.274258271791 ),
    point( -0.664067581296,  0.737143325619,  0.125035848469 ),
    point(  0.908638719469,  0.328001374379, -0.258439110592 ),
    point( -0.006195661612, -0.877383494750,  0.479749742895 ),
    point( -0.819451977499,  0.333629559726,  0.466036234051 ),
    point( -0.696725696325,  0.591963326558, -0.405157651752 ),
    point(  0.414521381259,  0.854920409620,  0.311902415007 ),
    point(  0.384615663439, -0.031426819973, -0.922541676089 ),
    point( -0.937710540369, -0.274158137850, -0.213392259553 ),
    point( -0.430031680502,  0.658785398118,  0.617312361486 ),
    point( -0.706191943958, -0.216149516404,  0.674219788052 ),
    point( -0.677302779630, -0.673867987469, -0.295233598910 ),
    point(  0.664067581296, -0.737143325619, -0.125035848469 ),
    point(  0.780043087900,  0.018379859626, -0.625455801375 ),
    point(  0.785617635585,  0.069047058932,  0.614847487770 ),
    point( -0.385449560359, -0.908763646148,  0.159928955138 ),
    point( -0.195297921076, -0.124718904495, -0.972781535238 ),
    point( -0.173958390951,  0.950530200265,  0.257353481837 ),
    point(  0.865198533051, -0.418355681002,  0.276423626579 ),
    point(  0.537705024704,  0.487319524400, -0.688035599887 ),
    point( -0.495700722560,  0.200530692004,  0.845025581308 ),
    point(  0.185202008113,  0.976284513250, -0.112110496499 ),
    point(  0.183002784848,  0.796911788173, -0.575709632598 ),
    point( -0.959049434401, -0.117280879058,  0.257816554978 ),
    point(  0.512413094752,  0.451499290764,  0.730466431938 ),
    point( -0.210907729343, -0.928675550967, -0.305089577101 ),
    point( -0.952798985876,  0.300218523480, -0.045198772103 ),
    point(  0.261558843777, -0.832393043675, -0.488578336313 ),
    point( -0.493113175035,  0.232372513972, -0.838356969878 ),
    point(  0.984755155630,  0.069671915844,  0.159383517690 ),
    point(  0.645784916356,  0.732241481543, -0.216296676546 ),
    point(  0.077671655454,  0.342571749352, -0.936275444925 ),
    point( -0.623813427053, -0.327840173617, -0.709491104819 ),
    point(  0.306698252447,  0.001059786417,  0.951806208119 ),
    point( -0.307305398397,  0.917119164951, -0.253881523386 ),
    point( -0.278146702796,  0.658472941257, -0.699319522828 ),
    point(  0.076424998231,  0.747313388623,  0.660062055103 ),
    point( -0.030075983144,  0.348389756866,  0.936867125332 ),
    point(  0.591635780409, -0.378209760413,  0.711986291222 ) );

c = cbspline( 3,
	      list( ctlpt( e2,  0.8,  1.0 ),
		    ctlpt( e2,  1.0,  0.8 ),
		    ctlpt( e2,  1.0, -0.8 ),
		    ctlpt( e2,  0.8, -1.0 ),
		    ctlpt( e2, -0.8, -1.0 ),
		    ctlpt( e2, -1.0, -0.8 ),
		    ctlpt( e2, -1.0,  0.8 ),
		    ctlpt( e2, -0.8,  1.0 ) ),
	      list( kv_periodic ) );

s = sFromCrvs( list( c,
		     c * sc( 0.7 ) * tz( 0.65 ),
		     c * sx( 0.65 ) * sy( 0.75 ) * tz( 0.7 ),
		     c * sc( 1.7 ) * tz( 1.1 ),
		     c * tz( 1.5 ) ),
	       3, kv_open );
color( s, yellow );

resolution = 70;

Silhs = nil();
# Loop with step one for slower, more complete result.
for ( i = 1, 2, sizeof( SphDirs ),
    # printf( "Processing vector %d\\n", list( i ) ):
    snoc( silhouette( s, coerce( nth( SphDirs, i ), vector_type ), true ),
	  silhs ) );
interact( list( s, Silhs ) );

save( "silh1", list( s, Silhs ) );

free( i );
free( c );
free( s );
free( Silhs );
free( SphDirs );

#############################################################################

s = torusSrf( 1, 0.3 );
color( s, magenta );

ViewMatFromViewDir = function( V ):
    return = RotZ2V( V )^-1 * rz( 90 ) * sc( 0.7 );

SilAndSilInfl = function( S, V ): Sil: Pts: E3Pts: i: p: view_mat_sil:
    Sil = silhouette( S, V, true ):
    color( Sil, yellow ):

    Pts = SSilInfl( S, V, 0.5, -1e-6 ):

    E3Pts = nil():

    for (i = 1, 1, sizeof( Pts ),
        p = nth( Pts, i ):
        snoc( coerce( seval( S, coord( p, 0 ), coord( p, 1 ) ), E3 ),
	      E3Pts ) ):
    color( E3Pts, cyan ):
    printf( "Detected %d silhouette high order contact points.\\n",
	    list( sizeof( E3Pts ) ) ):

    view_mat_sil = ViewMatFromViewDir( V ):

    return = list( E3Pts, Sil, view_mat_sil );

interact( All = list( axes, s, SilAndSilInfl( s, vector( 3, 1, 0.8 ) ) ) );

interact( All = list( axes, s, SilAndSilInfl( s, vector( 1, 1, 0.3 ) ) ) );

interact( All = list( axes, s, SilAndSilInfl( s, vector( 1, 2, 0.1 ) ) ) );

save( "silh2", All );
 
free( All );
free( s );

#############################################################################

resolution = save_res;