texture-display

#!/usr/bin/env perl
use strict;
use warnings;
use 5.010;

use OpenGL qw(:all);
use Math::Trig;
use Time::HiRes qw(sleep time);

####### GL HANDLERS
sub handler_resize {
	glViewport(0, 0, $_[0], $_[1]);
}

sub handler_idle {
	handler_render();

	glFlush();
	glutSwapBuffers();
	sleep(1 / 50);
}

sub init_gl {
	glutInit();
	glutInitDisplayMode(GLUT_DOUBLE | GLUT_RGBA | GLUT_DEPTH);
	glutInitWindowSize(512, 512);
	glutCreateWindow($_[0]);

	glutReshapeFunc   (\&handler_resize);
	glutIdleFunc      (\&handler_idle);
	glutDisplayFunc   (\&handler_render);
}

sub init_vp {
	glClearColor(0.0, 0.0, 0.0, 0.0);
	glColor3f(1.0, 1.0, 1.0);

	glMatrixMode(GL_PROJECTION);
	glOrtho(-1.0, 1.0, 1.0, -1.0, 1, -1);
	glMatrixMode(GL_TEXTURE);
	glMatrixMode(GL_MODELVIEW);

	glEnable(GL_TEXTURE_2D);
}

sub handler_render {
	# ...
	glClear(GL_COLOR_BUFFER_BIT);
	glLoadIdentity();

	glPushMatrix();
	glBegin(GL_QUADS);
		glTexCoord2f(0, 0); glVertex2f(-1, -1);
		glTexCoord2f(0, 1); glVertex2f(-1,  1);
		glTexCoord2f(1, 1); glVertex2f( 1,  1);
		glTexCoord2f(1, 0); glVertex2f( 1, -1);
	glEnd();
	glPopMatrix();
}


# load the data
my $data = do { local $/; open(my $fh, "<", $ARGV[0]) or die("Can't open $ARGV[0]: $!"); <$fh>; };

# texture resolution:
my $res;

if (defined($ARGV[1])) {
	# if specified by user, use that value.
	$res = $ARGV[1];
	print "texture resolution: $res (user defined)\n";
} elsif ($ARGV[0] =~ /-(\d+)$/) {
	# otherwise, derive from filename (files generated by dizzy contain that info)
	$res = $1;
	print "texture resolution: $res (from filename)\n";
} elsif (sqrt(length($data)) == int(sqrt(length($data)))) {
	# or from file size?
	$res = sqrt(length($data));
	print "texture resolution: $res (from filesize)\n";
} else {
	print "unknown texture resolution, please specify as second argument.\n";
	exit(1);
}

# init stuff

init_gl("file=$ARGV[0] res=$res");
init_vp();

# allocate new texture ID
my $new_texture = (glGenTextures_p(1))[0];
glBindTexture(GL_TEXTURE_2D, $new_texture);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);

glTexImage2D_s(
	GL_TEXTURE_2D, 0,
	GL_LUMINANCE,
	$res, $res,
	0,
	GL_LUMINANCE,
	GL_FLOAT,
	$data
);

glutMainLoop();