#!/usr/bin/env perl
#
# Bezier Surface example
#

use SDL;
use SDLx::App;
use SDL::Event;
use SDL::OpenGL;

my $app = SDLx::App->new( -w => 800, -h => 600, -d => 16, -gl => 1 );

my $knots      = pack "f8",  0,    0,   0,    0,    1,    1,    1,    1;
my $edgePts    = pack "f10", 0,    0,   1,    0,    1,    1,    0,    1, 0, 0;
my $curvePts   = pack "f8",  0.25, 0.5, 0.25, 0.75, 0.75, 0.75, 0.75, 0.5;
my $curveKnots = pack "f8",  0,    0,   0,    0,    1,    1,    1,    1;
my $pwlPts     = pack "f8",  0.75, 0.5, 0.5,  0.25, 0.25, 0.5,  0,    0;

sub init {
	glViewport( 0, 0, 800, 600 );
	glMatrixMode( GL_PROJECTION() );
	glLoadIdentity();
	glFrustum( -0.1, 0.1, -0.075, 0.075, 0.3, 100.0 );
	glMatrixMode( GL_MODELVIEW() );
	glLoadIdentity();
	glTranslate( 0, 0, -15 );
	glClearColor( 0.0, 0.0, 0.0, 0.0 );
	glShadeModel( GL_SMOOTH() );
}

sub initlight {
	glEnable( GL_LIGHTING() );
	glEnable( GL_LIGHT0() );
	glEnable( GL_DEPTH_TEST() );
	glEnable( GL_AUTO_NORMAL() );
	glEnable( GL_NORMALIZE() );
	glLight( GL_LIGHT0(), GL_AMBIENT(),  0.3, 0.3, 0.3, 1.0 );
	glLight( GL_LIGHT0(), GL_POSITION(), 1.0, 0.0, 2.0, 1.0 );
	glMaterial( GL_FRONT(), GL_DIFFUSE(),  0.6, 0.6, 0.6, 1.0 );
	glMaterial( GL_FRONT(), GL_SPECULAR(), 1.0, 1.0, 1.0, 1.0 );
	glMaterial( GL_FRONT(), GL_SHININESS(), 40.0 );
}

my ( $a, $b ) = ( 0, 90 );

my $ctrldata;

sub initpts {
	my @points;
	for my $u ( 0 .. 3 ) {
		for my $v ( 0 .. 3 ) {
			push @points, 2.0 * ( $u - 1.5 );
			push @points, 2.0 * ( $v - 1.5 );
			if ( ( $u == 1 || $u == 2 ) && ( $v == 1 || $v == 2 ) ) {
				push @points, 3.0;
			} else {
				push @points, -3.0;
			}
		}
	}
	$ctrldata = pack "f48", @points;
}

sub display {
	glClear( GL_COLOR_BUFFER_BIT() | GL_DEPTH_BUFFER_BIT() );
	glPushMatrix();
	glRotate( $a % 360, 0,  1, 0 );
	glRotate( $b % 360, -1, 0, 0 );
	glScale( 0.5, 0.5, 0.5 );
	$nurb = gluNewNurbsRenderer();
	gluNurbsProperty( $nurb, GLU_CULLING, GL_TRUE );
	gluBeginSurface($nurb);
	gluNurbsSurface(
		$nurb, 8, $knots, 8, $knots, 4 * 3, 3, $ctrldata, 4, 4,
		GL_MAP2_VERTEX_3
	);

	if ($toggle) {
		gluBeginTrim($nurb);
		gluPwlCurve( $nurb, 5, $edgePts, 2, GLU_MAP1_TRIM_2 );
		gluEndTrim($nurb);
		gluBeginTrim($nurb);
		gluNurbsCurve(
			$nurb, 8, $curveKnots, 2, $curvePts, 4,
			GLU_MAP1_TRIM_2
		);
		gluPwlCurve( $nurb, 3, $pwlPts, 2, GLU_MAP1_TRIM_2 );
		gluEndTrim($nurb);
	}

	gluEndSurface($nurb);

	glPopMatrix();
	$app->sync();
}

init();
initlight();
initpts();
display();

print STDERR <<USAGE;
Press:
q			Quit
t 			Toggle Curve & Trim
f			Toggle Fullscreen
Up/Down/Left/Right	Rotate

USAGE

my $event = SDL::Event->new;
$app->loop(
	{   SDL_QUIT()    => sub { exit(); },
		SDL_KEYDOWN() => sub {
			my ($event) = @_;
			if ( $event->key_sym() == SDLK_f ) {
				$app->fullscreen();
				display();
			} elsif ( $event->key_sym() == SDLK_t ) {
				$toggle = $toggle ? 0 : 1;
				display();
			} elsif ( $event->key_sym() == SDLK_q ) {
				exit();
			} else {
				if ( $event->key_sym() == SDLK_LEFT() ) {
					$a -= 10;
				} elsif ( $event->key_sym() == SDLK_RIGHT() ) {
					$a += 10;
				} elsif ( $event->key_sym() == SDLK_UP() ) {
					$b += 10;
				} elsif ( $event->key_sym() == SDLK_DOWN() ) {
					$b -= 10;
				}
				display();
			}
		},
	}
);