#
# Interpolation/least square approximation of curves and surfaces.
#
#					Gershon Elber, March 1994
#
#############################################################################

save_mat = view_mat;

view_mat = scale( vector( 0.6, 0.6, 0.6 ) );
viewobj( view_mat );
viewstate( "PolyAprx", 1 );

ri = iritstate( "RandomInit", 1964 );  # Seed-initiate the randomizer,
free( ri );

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

Len = 1.0;
NumPts = 50;

pl1 = nil();
for ( i = 1, 1, NumPts,
      Pt = ctlpt( E3, ( Random( -3.5, 3.5 ) + Len * i * 2 ) / NumPts,
		      ( Random( -3.5, 3.5 ) + Len * i * -5 ) / NumPts,
		      ( Random( -3.5, 3.5 ) + Len * i * Pi ) / NumPts ):
      snoc( Pt, pl1 ) );

LnFit = linterp( pl1 );
c1 = coerce( nth( LnFit, 1 ) + nth( LnFit, 2 ) * 10, e3 ) +
     coerce( nth( LnFit, 1 ) + nth( LnFit, 2 ) * -10, e3 );
color( c1, red );
interact( list( c1, pl1 ) * sc( 0.2 ) );

pl1 = nil();
for ( i = 1, 1, NumPts,
      Pt = ctlpt( E3, ( Random( -10, 10 ) + Len * i * -6 ) / NumPts,
		      ( Random( -10, 10 ) + Len * i * -1 ) / NumPts,
		      ( Random( -10, 10 ) + Len * i * Pi / 2 ) / NumPts ):
      snoc( Pt, pl1 ) );

LnFit = linterp( pl1 );
c1 = coerce( nth( LnFit, 1 ) + nth( LnFit, 2 ) * 10, e3 ) +
     coerce( nth( LnFit, 1 ) + nth( LnFit, 2 ) * -10, e3 );
color( c1, red );
interact( list( c1, pl1 ) * sc( 0.2 ) );

free( pl1 );
free( LnFit );
free( c1 );
free( Len );
free( NumPts );

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

pl1 = list( ctlpt( P3, 3.0, -0.5, -0.5, 0.0 ),
	    ctlpt( P3, 1.0,  0.7,  0.5, 0.1 ),
	    ctlpt( P3, 1.0, -0.2, -0.5, 0.2 ),
	    ctlpt( P3, 0.8,  0.9,  0.5, 0.3 ),
	    ctlpt( P3, 2.0,  0.1, -0.5, 0.4 ) );

c1 = cinterp( pl1, 3, 3, PARAM_UNIFORM, false );
interact( list( c1, pl1 ) );

c1 = cinterp(  pl1, 3, 4, PARAM_UNIFORM, false );
interact( list( c1, pl1 ) );

c1 = cinterp(  pl1, 3, 5, PARAM_UNIFORM, false );
interact( list( c1, pl1 ) );

c1 = cinterp(  pl1, 4, 4, PARAM_UNIFORM, false );
interact( list( c1, pl1 ) );

c1 = cinterp(  pl1, 4, 0, PARAM_UNIFORM, false );
interact( list( c1, pl1 ) );

c1 = cinterp(  pl1, 5, 5, PARAM_UNIFORM, false );
interact( list( c1, pl1 ) );

c1 = cinterp(  pl1, 5, 7, PARAM_UNIFORM, false );
interact( list( c1, pl1 ) );

save( "interpl1", list( c1, pl1 ) );

free( c1 );
free( pl1 );

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

ppl1 = nil();
Len = 1.0;
NumPts = 10;
for ( i = 1, 1, NumPts,
      R = random( 0.5, 0.9 ):
      Pt = ctlpt( E2, Len * R * cos( i * 2 * pi / NumPts ),
		      Len * R * sin( i * 2 * pi / NumPts ) ):
      snoc( Pt, ppl1 ) );

c1 = cinterp( ppl1, 3, 3, PARAM_UNIFORM, true );
interact( list( c1, ppl1 ) );

c1 = cinterp(  ppl1, 3, 4, PARAM_UNIFORM, true );
interact( list( c1, ppl1 ) );

c1 = cinterp(  ppl1, 3, 5, PARAM_UNIFORM, true );
interact( list( c1, ppl1 ) );

c1 = cinterp(  ppl1, 4, 4, PARAM_UNIFORM, true );
interact( list( c1, ppl1 ) );

c1 = cinterp(  ppl1, 4, 0, PARAM_UNIFORM, true );
interact( list( c1, ppl1 ) );

c1 = cinterp(  ppl1, 5, 5, PARAM_UNIFORM, true );
interact( list( c1, ppl1 ) );

c1 = cinterp(  ppl1, 5, 7, PARAM_UNIFORM, true );
interact( list( c1, ppl1 ) );

c1 = cinterp(  ppl1, 4, 10, PARAM_UNIFORM, true );
interact( list( c1, ppl1 ) );
save( "interpl2", list( c1, ppl1 ) );

ppl1 = nil();
Len = 1.0;
NumPts = 50;
for ( i = 1, 1, NumPts,
      R = random( 0.5, 0.9 ):
      Pt = ctlpt( P2, 0.5 + R,
		      Len * R * cos( i * 2 * pi / NumPts ),
		      Len * R * sin( i * 2 * pi / NumPts ) ):
      snoc( Pt, ppl1 ) );
free( pt );
free( i );
free( R );

c1 = cinterp( ppl1, 2, 20, PARAM_UNIFORM, true );
interact( list( c1, ppl1 ) );

c1 = cinterp( ppl1, 3, 15, PARAM_UNIFORM, true );
interact( list( c1, ppl1 ) );

c1 = cinterp(  ppl1, 4, 30, PARAM_UNIFORM, true );
interact( list( c1, ppl1 ) );

c1 = cinterp(  ppl1, 4, 50, PARAM_UNIFORM, true );
interact( list( c1, ppl1 ) );
save( "interpl3", list( c1, ppl1 ) );

free( c1 );
free( ppl1 );
free( NumPts );
free( Len );

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

pl2 = nil();
for ( x = 0, 1, 20,
	snoc(point(x / 10 - 1, sin(x * Pi / 5), 0.0), pl2)
    );
free( x );

c2 = cinterp( pl2, 3, 5, PARAM_UNIFORM, false );
interact( list( c2, pl2 ) );

c2 = cinterp( pl2, 3, 7, PARAM_UNIFORM, false );
interact( list( c2, pl2 ) );

c2 = cinterp( pl2, 3, 10, PARAM_UNIFORM, false );
interact( list( c2, pl2 ) );

c2 = cinterp( pl2, 4, 5, PARAM_UNIFORM, false );
interact( list( c2, pl2 ) );

c2 = cinterp( pl2, 4, 7, PARAM_UNIFORM, false );
interact( list( c2, pl2 ) );

c2 = cinterp( pl2, 4, 10, PARAM_UNIFORM, false );
interact( list( c2, pl2 ) );

c2 = cinterp( pl2, 4, 15, PARAM_UNIFORM, false );
interact( list( c2, pl2 ) );

c2 = cinterp( pl2, 4, 20, PARAM_UNIFORM, false );
interact( list( c2, pl2 ) );

c2 = cinterp( pl2, 10, 10, PARAM_UNIFORM, false );
interact( list( c2, pl2 ) );

c2 = cinterp( pl2, 10, 20, PARAM_UNIFORM, false );
interact( list( c2, pl2 ) );
save( "interpl4", list( c2, pl2 ) );

free( c2 );
free( pl2 );

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

view_mat = roty(30) * rotx(50) * scale( vector( 0.5, 0.5, 0.5 ) );
viewobj(view_mat);

pl3 = nil();
for ( x = 0, 1, 30,
	snoc( point( ( x / 15 - 1 ) * cos( x ),
		     ( x / 15 - 1 ) * sin( x ),
		     x / 15 - 1 ),
	      pl3 )
    );
free( x );

c3a = cinterp( pl3, 3, 5, PARAM_UNIFORM, false );
color(c3a, magenta);
c3b = cinterp( pl3, 3, 5, PARAM_CHORD, false );
color(c3b, red);
c3c = cinterp( pl3, 3, 5, PARAM_CENTRIP, false );
color(c3c, cyan);
c3d = cinterp( pl3, 3, 5, PARAM_NIELFOL, false );
color(c3d, yellow);
interact( list( c3a, c3b, c3c, c3d, pl3 ) );

c3a = cinterp( pl3, 3, 10, PARAM_UNIFORM, false );
color(c3a, magenta);
c3b = cinterp( pl3, 3, 10, PARAM_CHORD, false );
color(c3b, red);
c3c = cinterp( pl3, 3, 10, PARAM_CENTRIP, false );
color(c3c, cyan);
c3d = cinterp( pl3, 3, 10, PARAM_NIELFOL, false );
color(c3d, yellow);
interact( list( c3a, c3b, c3c, c3d, pl3 ) );

c3a = cinterp( pl3, 3, 20, PARAM_UNIFORM, false );
color(c3a, magenta);
c3b = cinterp( pl3, 3, 20, PARAM_CHORD, false );
color(c3b, red);
c3c = cinterp( pl3, 3, 20, PARAM_CENTRIP, false );
color(c3c, cyan);
c3d = cinterp( pl3, 3, 20, PARAM_NIELFOL, false );
color(c3d, yellow);
interact( list( c3a, c3b, c3c, c3d, pl3 ) );

c3a = cinterp( pl3, 5, 5, PARAM_UNIFORM, false );
color(c3a, magenta);
c3b = cinterp( pl3, 5, 5, PARAM_CHORD, false );
color(c3b, red);
c3c = cinterp( pl3, 5, 5, PARAM_CENTRIP, false );
color(c3c, cyan);
c3d = cinterp( pl3, 5, 5, PARAM_NIELFOL, false );
color(c3d, yellow);
interact( list( c3a, c3b, c3c, c3d, pl3 ) );

c3a = cinterp( pl3, 5, 10, PARAM_UNIFORM, false );
color(c3a, magenta);
c3b = cinterp( pl3, 5, 10, PARAM_CHORD, false );
color(c3b, red);
c3c = cinterp( pl3, 5, 10, PARAM_CENTRIP, false );
color(c3c, cyan);
c3d = cinterp( pl3, 5, 10, PARAM_NIELFOL, false );
color(c3d, yellow);
interact( list( c3a, c3b, c3c, c3d, pl3 ) );

c3a = cinterp( pl3, 5, 20, PARAM_UNIFORM, false );
color(c3a, magenta);
c3b = cinterp( pl3, 5, 20, PARAM_CHORD, false );
color(c3b, red);
c3c = cinterp( pl3, 5, 20, PARAM_CENTRIP, false );
color(c3c, cyan);
c3d = cinterp( pl3, 5, 20, PARAM_NIELFOL, false );
color(c3d, yellow);
interact( list( c3a, c3b, c3c, c3d, pl3 ) );

c3a = cinterp( pl3, 5, 25, PARAM_UNIFORM, false );
color(c3a, magenta);
c3b = cinterp( pl3, 5, 25, PARAM_CHORD, false );
color(c3b, red);
c3c = cinterp( pl3, 5, 25, PARAM_CENTRIP, false );
color(c3c, cyan);
#c3d = cinterp( pl3, 5, 25, PARAM_NIELFOL, false );
color(c3d, yellow);
interact( list( c3a, c3b, c3c, c3d, pl3 ) );

save( "interpl5", list( c3a, c3b, c3c, c3d, pl3 ) );

free( c3a );
free( c3b );
free( c3c );
free( c3d );
free( pl3 );

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

pl4 = nil();
for ( x = 0, 1, 100,
	snoc(point(cos(x / 5), sin(x / 5), x / 50 - 1), pl4)
    );
free( x );

c4 = cinterp( pl4, 3, 5, PARAM_UNIFORM, false );
interact( list( c4, pl4 ) );

c4 = cinterp( pl4, 3, 10, PARAM_UNIFORM, false );
interact( list( c4, pl4 ) );

c4 = cinterp( pl4, 3, 21, PARAM_UNIFORM, false );
interact( list( c4, pl4 ) );

c4 = cinterp( pl4, 5, 5, PARAM_UNIFORM, false );
interact( list( c4, pl4 ) );

c4 = cinterp( pl4, 5, 10, PARAM_UNIFORM, false );
interact( list( c4, pl4 ) );

c4 = cinterp( pl4, 5, 21, PARAM_UNIFORM, false );
interact( list( c4, pl4 ) );
save( "interpl6", list( c4, pl4 ) );

free( c4 );
free( pl4 );

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

view_mat = scale( vector( 0.7, 0.7, 0.7 ) );
viewobj( view_mat );

pl5 = nil();
for ( x = 0, 1, 4,
	t = ( x / 2 ) - 1:
	snoc( point( t * t * t, t * t * t * t * t, 0.0 ), pl5 )
    );
free( x );
free( t );

c5a = cinterp( pl5, 3, 3, PARAM_UNIFORM, false );
color(c5a, magenta);
c5b = cinterp( pl5, 3, 3, PARAM_CHORD, false );
color(c5b, red);
c5c = cinterp( pl5, 3, 3, PARAM_CENTRIP, false );
color(c5c, cyan);
c5d = cinterp( pl5, 3, 3, PARAM_NIELFOL, false );
color(c5d, yellow);
interact( list( c5a, c5b, c5c, c5d, pl5 ) );

c5a = cinterp( pl5, 3, 4, PARAM_UNIFORM, false );
color(c5a, magenta);
c5b = cinterp( pl5, 3, 4, PARAM_CHORD, false );
color(c5b, red);
c5c = cinterp( pl5, 3, 4, PARAM_CENTRIP, false );
color(c5c, cyan);
c5d = cinterp( pl5, 3, 4, PARAM_NIELFOL, false );
color(c5d, yellow);
interact( list( c5a, c5b, c5c, c5d, pl5 ) );

c5a = cinterp( pl5, 3, 5, PARAM_UNIFORM, false );
color(c5a, magenta);
c5b = cinterp( pl5, 3, 5, PARAM_CHORD, false );
color(c5b, red);
c5c = cinterp( pl5, 3, 5, PARAM_CENTRIP, false );
color(c5c, cyan);
c5d = cinterp( pl5, 3, 5, PARAM_NIELFOL, false );
color(c5d, yellow);
interact( list( c5a, c5b, c5c, c5d, pl5 ) );
save( "interpl7", list( c5a, c5b, c5c, c5d, pl5 ) );

free( c5a );
free( c5b );
free( c5c );
free( c5d );
free( pl5 );

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

view_mat = scale( vector( 0.7, 0.7, 0.7 ) );
viewobj( view_mat );

cbzr = cbezier( list( ctlpt( E3, -0.5,  0.7,  0.2 ),
		      ctlpt( E3, -0.3, -0.8,  1.0 ),
		      ctlpt( E3,  0.1, -0.9, -2.0 ),
		      ctlpt( E3,  0.3,  0.9,  1.0 ),
		      ctlpt( E3,  0.6,  0.1,  0.1 ) ) );
color( cbzr, green );

pl6 = nil();
for ( x = 0, 1, 4,
	snoc(ceval(cbzr, x / 4), pl6)
    );

c6a = cinterp( pl6, 5, 5, list( list( 0, 0.25, 0.5, 0.75, 1 ),
			        list( kv_open ) ), false );
color(c6a, magenta);
c6b = cinterp( pl6, 5, 5, list( list( 0, 0.2, 0.3, 0.5, 1 ),
			        list( kv_open ) ), false );
color(c6b, red);
c6c = cinterp( pl6, 5, 5, list( list( 0, 0.3, 0.7, 0.9, 1 ),
			        list( kv_open ) ), false );
color(c6c, cyan);
c6d = cinterp( pl6, 5, 5, list( list( 0, 0.2, 0.3, 0.4, 0.5 ),
			        list( kv_open ) ), false );
color(c6d, yellow);
interact( list( cbzr, c6a, c6b, c6c, c6d, pl6 ) );
save( "interpl8", list( cbzr, c6a, c6b, c6c, c6d, pl6 ) );


c6a = cinterp( pl6, 5, 5, list( list( 0, 0.25, 0.5, 0.75, 1 ),
			        list( kv_open ) ), false );
color(c6a, magenta);
c6b = cinterp( pl6, 5, 5, list( list( 0, 0.25, 0.5, 0.75, 1 ),
			        list( -4, -3, -2, -1, 0, 1, 2, 3, 4, 5 ) ), false );
color(c6b, magenta);
c6c = cinterp( pl6, 3, 5, list( list( 0, 0.25, 0.5, 0.75, 1 ),
			        list( 0, 0, 0, 1/3, 2/3, 1, 1, 1 ) ), false );
color(c6c, cyan);
c6d = cinterp( pl6, 3, 5, list( list( 0, 0.25, 0.5, 0.75, 1 ),
			        list( 0, 0, 0, 0.2, 0.8, 1, 1, 1 ) ), false );
color(c6d, yellow);
interact( list( cbzr, c6a, c6b, c6c, c6d, pl6 ) );
save( "interpl9", list( cbzr, c6a, c6b, c6c, c6d, pl6 ) );

c6a = cinterp( pl6, 3, 3, PARAM_UNIFORM, false );
color(c6a, magenta);
c6b = cinterp( pl6, 3, 3, PARAM_CHORD, false );
color(c6b, red);
c6c = cinterp( pl6, 3, 3, PARAM_CENTRIP, false );
color(c6c, cyan);
c6d = cinterp( pl6, 3, 3, PARAM_NIELFOL, false );
color(c6d, yellow);
interact( list( cbzr, c6a, c6b, c6c, c6d, pl6 ) );

c6a = cinterp( pl6, 3, 4, PARAM_UNIFORM, false );
color(c6a, magenta);
c6b = cinterp( pl6, 3, 4, PARAM_CHORD, false );
color(c6b, red);
c6c = cinterp( pl6, 3, 4, PARAM_CENTRIP, false );
color(c6c, cyan);
c6d = cinterp( pl6, 3, 4, PARAM_NIELFOL, false );
color(c6d, yellow);
interact( list( cbzr, c6a, c6b, c6c, c6d, pl6 ) );

c6a = cinterp( pl6, 3, 5, PARAM_UNIFORM, false );
color(c6a, magenta);
c6b = cinterp( pl6, 3, 5, PARAM_CHORD, false );
color(c6b, red);
c6c = cinterp( pl6, 3, 5, PARAM_CENTRIP, false );
color(c6c, cyan);
c6d = cinterp( pl6, 3, 5, PARAM_NIELFOL, false );
color(c6d, yellow);
interact( list( cbzr, c6a, c6b, c6c, c6d, pl6 ) );

c6a = cinterp( pl6, 5, 5, PARAM_UNIFORM, false );
color(c6a, magenta);
c6b = cinterp( pl6, 5, 5, PARAM_CHORD, false );
color(c6b, red);
c6c = cinterp( pl6, 5, 5, PARAM_CENTRIP, false );
color(c6c, cyan);
c6d = cinterp( pl6, 5, 5, PARAM_NIELFOL, false );
color(c6d, yellow);
interact( list( cbzr, c6a, c6b, c6c, c6d, pl6 ) );
save( "interp10", list( cbzr, c6a, c6b, c6c, c6d, pl6 ) );

free( cbzr );
free( c6a );
free( c6b );
free( c6c );
free( c6d );
free( pl6 );

#############################################################################
EchoSrc = iritState( "EchoSource", false );
include( "gersktch" );
EchoSrc = iritState( "EchoSource", EchoSrc );
free( EchoSrc );
color( gershon, red );

gershon_a = cinterp( gershon, 3, 3, PARAM_UNIFORM, false );
color(gershon_a, green);
interact( list( gershon, gershon_a ) );

gershon_b = cinterp( gershon, 3, 6, PARAM_UNIFORM, false );
color(gershon_b, green);
interact( list( gershon, gershon_b ) );

gershon_c = cinterp( gershon, 3, 12, PARAM_UNIFORM, false );
color(gershon_c, green);
interact( list( gershon, gershon_c ) );

gershon_d = cinterp( gershon, 3, 24, PARAM_UNIFORM, false );
color(gershon_d, green);
interact( list( gershon, gershon_d ) );

gershon_e = cinterp( gershon, 3, 48, PARAM_UNIFORM, false );
color(gershon_e, green);
interact( list( gershon, gershon_e ) );

gershon_f = cinterp( gershon, 3, 96, PARAM_UNIFORM, false );
color(gershon_f, green);
interact( list( gershon, gershon_f ) );
save( "interp11", list( gershon, gershon_f ) );

free( gershon );
free( gershon_a );
free( gershon_b );
free( gershon_c );
free( gershon_d );
free( gershon_e );
free( gershon_f );

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

DerivPt1 = ctlpt( E2,  1, 0 );
DerivPt2 = ctlpt( E2,  5, 5 );
attrib( DerivPt1, "derivative", 1 );
attrib( DerivPt2, "derivative", 1 );
pll = list( ctlpt( E2, -0.5,  0.7 ),
	    ctlpt( E2, -0.3, -0.8 ),
	    Pt1 = ctlpt( E2,  0.0,  0.0 ),
	    ctlpt( E2,  0.3,  0.9 ),
	    Pt2 = ctlpt( E2,  0.6,  0.1 ),
	    DerivPt1,
	    DerivPt2 );
c7 = cinterp( pll, 5, 7, list( list( 0, 0.15, 0.5, 0.87, 1.0, 0.5, 1.0 ),
			       list( kv_open ) ), false );

DeriveVecs = list( arrow3d( Pt1, coerce( DerivPt1, vector_type ),
		   0.2, 0.005, 0.05, 0.015 ),
		   arrow3d( Pt2, coerce( DerivPt2, vector_type ),
		   0.5, 0.01, 0.1, 0.03 ) );
color( DeriveVecs, red );
interact( list( c7, Pll, DeriveVecs ) );
save( "interp12", list( c7, Pll, DeriveVecs ) );

free( DeriveVecs );
free( DerivPt1 );
free( DerivPt2 );
free( Pt1 );
free( Pt2 );
free( Pll );
free( c7 );

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

view_mat = rotz(50) * rotx(-60) * scale( vector( 0.2, 0.2, 0.2 ) );
viewobj(view_mat);

pl = nil();
pll = nil();
for ( x = -5, 1, 5,
      pl = nil():
      for ( y = -5, 1, 5,
	    snoc( point( x, y, sin( x * Pi / 2 ) * cos( y * Pi / 2 ) ),
		  pl )
	  ):
      snoc( pl, pll ) );
free( x );
free( y );

s1 = -sinterp( pll, 3, 3, 3, 3, PARAM_UNIFORM );
interact( list( pll, s1 ) );

s1 = -sinterp( pll, 3, 3, 0, 0, PARAM_UNIFORM );
interact( list( pll, s1 ) );

s1 = -sinterp( pll, 3, 3, 4, 11, PARAM_UNIFORM );
interact( list( pll, s1 ) );

s1 = -sinterp( pll, 3, 3, 11, 11, PARAM_UNIFORM );
interact( list( pll, s1 ) );

save( "interp13", list( pll, s1 ) );

free( pl );
free( pll );
free( s1 );

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

view_mat = rotz(50) * rotx(-60) * scale( vector( 0.7, 0.7, 0.7 ) );
viewobj(view_mat);

pl = nil();
pll = nil();
for ( x = -5, 1, 5,
      pl = nil():
      xx = x * Pi / 5:
      for ( y = -5, 1, 5,
	    yy = y * Pi / 10:
	    snoc( point( cos( xx ) * cos( yy ),
		         sin( xx ) * cos( yy ),
		         sin( yy ) ),
		 pl)
	  ):
      snoc( pl, pll ) );
free( x );
free( xx );
free( y );
free( yy );

s2 = -sinterp( pll, 3, 3, 6, 6, PARAM_UNIFORM );
interact( list( pll, s2 ) );

s2 = -sinterp( pll, 3, 3, 11, 11, PARAM_UNIFORM );
interact( list( pll, s2 ) );

save( "interp14", list( pll, s2 ) );

free( pl );
free( pll );
free( s2 );

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

pl = nil();
pll = nil();
for ( x = -10, 1, 10,
      pl = nil():
      xx = x * Pi / 10:
      for ( y = -10, 1, 10,
	    yy = y * Pi / 20:
	    snoc( point( cos( xx )^3 * cos( yy )^3,
		         sin( xx )^3 * cos( yy )^3,
		         sin( yy )^3 ),
		 pl)
	  ):
      snoc( pl, pll ) );
free( x );
free( xx );
free( y );
free( yy );

s3 = -sinterp( pll, 3, 3, 11, 11, PARAM_UNIFORM );
interact( list( pll, s3 ) );

s3 = -sinterp( pll, 3, 3, 21, 21, PARAM_UNIFORM );
interact( list( pll, s3 ) );

save( "interp15", list( pll, s3 ) );

free( pl );
free( pll );
free( s3 );

#############################################################################
# Scattered Data Interpolation.
#############################################################################

pl = list( ctlpt( E3, 0, 0, 0 ),
	   ctlpt( E3, 0, 1, 0 ),
	   ctlpt( E3, 1, 0, 0 ),
	   ctlpt( E3, 1, 1, 0 ) );
for ( x = 0, 90, 270,
    xx = x * Pi / 180:
    snoc( ctlpt( E3, 0.3 * cos( xx ) + 0.5, 0.3 * sin( xx ) + 0.5, 1.0 ), pl ) );
free( x );
free( xx );

s4 = coerce( sinterp( pl, 3, 3, 3, 3, PARAM_UNIFORM ), e3 )
	* rotx( -90 ) * roty( -90 );

interact( list( axes, s4, pl ) );
save( "interp16", list( axes, s4, pl ) );

free( s4 );
free( pl );

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

size = 8;
pl = nil();
for ( x = -size, 2, size,
    for ( y = -size, 2, size,
	snoc( ctlpt( E3, (x + size) / (2 * size), (y + size) / (2 * size),
		     cos( x / 5 ) * sin( y / 5 ) ),
	      pl ) ) );

free( size );
free( x );
free( y );

s5 = coerce( sinterp( pl, 3, 3, 6, 6, PARAM_UNIFORM ), e3 )
	* rotx( -90 ) * roty( -90 );
interact( list( pl, s5 ) );
save( "interp17", list( pl, s5 ) );

free( s5 );
free( pl );

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

pl = nil();
for ( teta = -5, 1, 5,
    t = teta * Pi / 10:
    for ( phi = 0, 1, 9,
	p = phi * 2 * Pi / 9:
	snoc( ctlpt( E5, (teta + 5) / 10,
		         phi / 9,
		         cos( t ) * cos( p ),
		         cos( t ) * sin( p ),
			 sin( t ) ),
	      pl ) ) );

free( p );
free( phi );
free( t );
free( teta );

s6 = -sinterp( pl, 3, 3, 7, 7, PARAM_UNIFORM );
interact( s6 ); # We cannot view pl as it is in E5 space (u, v, x, y, z)
save( "interp18", list( s6 ) );

free( s6 );
free( pl );

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

view_mat = save_mat;