#!/usr/bin/perl

# Copyright (C) 2002 Jonas Jermann
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 2 of the License, or
# (at your option) any later version.
# 
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
# 
# You should have received a copy of the GNU General Public License
# along with this program; if not, write to the Free Software
# Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
# 
# The author may be reached as <jjermann@gmx.net>
# 
# pfy rulez!
# (told me to write it down... ;-)


# modules
use OpenGL ":old",":glutfunctions",":gluconstants",":functions";
use Time::HiRes qw (gettimeofday tv_interval usleep);
use strict; no strict "subs";
use Math::Trig;

# global variables
our ($PI,$tsize,$zsize,$time,$n,$z,$t,@tri2d,@tri3d, @yreal,@options,$cfact,$fps,$xmin,$xmax,$ymin,$ymax,$zmin,$zmax,$tmin,$tmax,$xres,$zres,$tres, $width,$height);


@options = (2,0,0,1);
	# 0(0): 2d
	# 0(1): 3d wire
	# 0(2): 3d solid
	# 1(0): stable
	# 1(1): time-function forward
	# 1(2): time-function backward
	# 2(0): orthographic viewing
	# 2(1): perspective viewing
	# 2(2): stereo viewing
	# 2(3): 2nd way of stereo viewing
	# 3(0): no colours
	# 3(1): color-mode 1
	# 3(2): color-mode 2 (pfy)

# window
$xmin = -5;
$xmax = 5;
$ymin = -5;
$ymax = 4;
$zmin = -5;
$zmax = 5;
$tmin = -4;
$tmax = 4;

# points/axis and misc
$xres = 20;
$zres = 30;
$tres = 30;
$fps = 30;
$cfact = 1.5;

# variables init
$z = $zmin;
$t = $tmin;
$n = 0;
$time = [gettimeofday];
$zsize = 0;
$tsize = 0;
$PI = 3.415926535898;

# main program ;-)
init();
glutMainLoop;


sub init{
    # glut init
    glutInit(@ARGV);
    glutInitDisplayMode(GLUT_DOUBLE | GLUT_RGB | GLUT_DEPTH);
    glutInitWindowSize(1024, 768);
    glutInitWindowPosition(0, 0);
    glutCreateWindow("graph window");
    glutFullScreen();

    # functions
    glutKeyboardFunc(\&keyboard);
    glutDisplayFunc(\&display);
    glutReshapeFunc(\&resize);
    glutIdleFunc(\&idle);

    glClearColor(0,0,0,0);
    glMatrixMode(GL_PROJECTION);

    glOrtho($xmin,$xmax,$ymin,$ymax,$zmin,$zmax);
    glRotatef(-50, 5, -0.5, 0.0);
    glScalef(0.8,0.8,0.8); 

    reset();
}    


sub scolor { 
	if ($options[3] == 1) { glColor3f(0.8*sin($_[0]*$cfact),0.8*sin($_[0]*$cfact+2*$PI/3),0.8*sin($_[0]*$cfact+4*$PI/3)); }
	elsif ($options[3] == 2) { 
		my ($r,$b,$g,$a);
		$r=$b=$g=0; 
		$a=(($_[0]-$ymin)/($ymax-$ymin)*$cfact);
		
		$r=$a*3;
		$r=1 if ($r > 1);
		
		$g=($a*3-1) if ((($a*3-1) > 0));
		$g=1 if ($g > 1);
		
		$b=($a*3-2) if ((($a*3-2) > 0));
		$b=1 if ($b > 1);
		
		glColor3f($r,$g,$b);
	}
}

sub resize{ ($width,$height)=@_; }

sub reset {
    # gl init
    glLoadIdentity();
           
    # window properties
    glFlush();
    
    # calculation
    idle();
}


sub idle {
    my (@tripar,$dim,$x,$y,$j);
    
    if ($options[0] == 0) {$dim=2;} 
    else {$dim=3;}

    if ($zsize < $zres) {
	$x=$xmin;
	for ($j=0; $j<=($dim*$xres-$dim); $j=$j+$dim) {

	    $yreal[0] = "2*cos(t*sqrt(z*z+x*x)-2*atan(x/z))";
	    $yreal[1] = "(cos(t*sqrt(z*z+x*x))-sin(t*sqrt(z*z+x*x)))*exp(-sqrt(z*z+x*x))*5";
	    $yreal[2] = "0.1*z*sin(t*(z-x))-x*cos(z*x-t)";
	    $yreal[3] = "sqrt(t*(1-z*z-x*x))";
	    $yreal[4] = "sin(x*x+z*z+t*t)";

    	    $yreal[$n] =~ s/(?<!\w)([xzt])(?!\w)/\$$1$2/g;
    	    $yreal[$n] =~ s/PI/\$PI/g;

	    $y = eval ($yreal[$n]);
    	    $tripar[$j]=$x;
    	    $tripar[$j+1]=$y;
    	    if ($dim == 3) {$tripar[$j+2]=$z;}
    	    $x += ($xmax-$xmin)/($xres-1); 
	}

	$j = 0;
	if ($dim == 3) { $z += ($zmax-$zmin)/($zres-1); $zsize++; }
	elsif ($dim == 2) { $zsize = $zres + 1;}
	
	if ($dim == 3) { unshift(@tri3d,@tripar); splice(@tri3d,(9*$xres*$zres)); if ($zsize == $zres) { display();} }
	else { unshift(@tri2d,@tripar); splice(@tri2d,(2*$xres)); display(); } 
    }
    elsif (($options[1] == 1) and ($tsize < $tres)) { $zsize=0;	$z=$zmin; $t += ($tmax-$tmin)/($tres-1); $tsize++; }
    elsif (($options[1] == 2) and ($tsize > 0)) { $zsize=0; $z=$zmin; $t -= ($tmax-$tmin)/($tres-1); $tsize--; }
    elsif ($options[1] == 1) { $options[1]=2; }
    elsif ($options[1] == 2) { $options[1]=1; }
    
}
    

sub display {
    my ($h,$i);

    if (tv_interval($time)<(1/$fps)) { usleep (1/120); return; }
    $time = [gettimeofday];
    glClear (GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
    glColor3f(0.8,0.8,0.8);
    
    # display2d()
    if ($options[0] == 0) {
	glBegin(GL_LINE_STRIP); {
	    if ($options[3] > 0) {scolor($tri2d[1]); }
	    glVertex2f($tri2d[0],$tri2d[1]);
	    for ($i=2; $i<=(2*$xres-2); $i=$i+2) { 
	    	if ($options[3] > 0) {scolor($tri2d[$i+1]); }
	    	glVertex2f($tri2d[$i],$tri2d[$i+1]); }
	} glEnd();
    }
 
    
    # display3d_wire()
    elsif ($options[0] == 1) {
	for $h (0..($zsize-2)) {
	    glBegin(GL_LINE_STRIP); {
	    	# jeweils um einen Punkt springen
	    	for ($i=0; $i<=(3*$xres-4); $i=$i+3) {
		    my $basec = $i+1+3*$h*$xres;
		    # left bottom
		    if ($options[3] > 0) {scolor($tri3d[$basec]); }
		    glVertex3f($tri3d[$basec-1],$tri3d[$basec],$tri3d[$basec+1]);
		    # left top
		    if ($options[3] > 0) {scolor($tri3d[$basec+3*$xres]); }
		    glVertex3f($tri3d[$basec-1+3*$xres],$tri3d[$basec+3*$xres],$tri3d[$basec+1+3*$xres]);
		    # rigth top
		    if ($options[3] > 0) {scolor($tri3d[$basec+3+3*$xres]); }
		    glVertex3f($tri3d[$basec+2+3*$xres],$tri3d[$basec+3+3*$xres],$tri3d[$basec+4+3*$xres]);
		    # left bottom
		    if ($options[3] > 0) {scolor($tri3d[$basec]); }
		    glVertex3f($tri3d[$basec-1],$tri3d[$basec],$tri3d[$basec+1]); }
		    if ($options[3] > 0) {scolor($tri3d[3*$xres-2+3*$h*$xres]); }
		    glVertex3f($tri3d[3*$xres-3+3*$h*$xres],$tri3d[3*$xres-2+3*$h*$xres],$tri3d[3*$xres-1+3*$h*$xres]); 
		    if ($options[3] > 0) {scolor($tri3d[3*$xres-2+3*$h*$xres+3*$xres]); }
		    glVertex3f($tri3d[3*$xres-3+3*$h*$xres+3*$xres],$tri3d[3*$xres-2+3*$h*$xres+3*$xres],$tri3d[3*$xres-1+3*$h*$xres+3*$xres]); 
	    } glEnd();
	}
    }

    
    # display3d_solid()
    elsif ($options[0] == 2) {
        $time = [gettimeofday];
        glBegin(GL_TRIANGLES);
        {
	    for $h (0..($zsize-2)) {
		for ($i=0; $i<=(3*$xres-4); $i=$i+3) {
		    my $basec = $i+1+3*$h*$xres;
		    # left bottom
		    if ($options[3] > 0) {scolor($tri3d[$basec]); }
		    glVertex3f($tri3d[$basec-1],$tri3d[$basec],$tri3d[$basec+1]);
		    # left top
		    if ($options[3] > 0) {scolor($tri3d[$basec+3*$xres]); }
		    glVertex3f($tri3d[$basec+3*$xres-1],$tri3d[$basec+3*$xres],$tri3d[$basec+3*$xres+1]); 
		    # right bottom
		    if ($options[3] > 0) {scolor($tri3d[$basec+3]); }
		    glVertex3f($tri3d[$basec+2],$tri3d[$basec+3],$tri3d[$basec+4]); 
		    # left top
		    if ($options[3] > 0) {scolor($tri3d[$basec+3*$xres]); }
		    glVertex3f($tri3d[$basec+3*$xres-1],$tri3d[$basec+3*$xres],$tri3d[$basec+3*$xres+1]); 
		    # right top
		    if ($options[3] > 0) {scolor($tri3d[$basec+3*$xres+3]); }
		    glVertex3f($tri3d[$basec+3*$xres+2],$tri3d[$basec+3*$xres+3],$tri3d[$basec+3*$xres+4]); 
		    # right bottom
		    if ($options[3] > 0) {scolor($tri3d[$basec+3]); }
		    glVertex3f($tri3d[$basec+2],$tri3d[$basec+3],$tri3d[$basec+4]); 
		}
	    }
	} glEnd();
    }

	
    
    glFlush();
    glutSwapBuffers();    
}


sub keyboard {
    my ($key) = @_; $key = chr($key);
    
    # misc
    if   ($key=~/q/i){ exit(); }
    elsif($key=~/m/i){ screenshot(); }
    elsif($key=~/3/i){ $cfact=$cfact*0.98; }
    elsif($key=~/4/i){ $cfact=$cfact*1.02; }
    # function change
    elsif($key=~/n/i){ $n++; $zsize=0; $z=$zmin; }
    elsif(($key=~/b/i) and ($n > 0)){ $n--; $zsize=0; $z=$zmin; }
    # mode change
    elsif(($key=~/1/i) and ($options[0]>0)){ $options[0]--; $zsize=0; $z=$zmin; }
    elsif(($key=~/2/i) and ($options[0]<2)){ $options[0]++; $zsize=0; $z=$zmin; }
    elsif($key=~/c/i) { 
	if ($options[3] < 3) { $options[3]++; }
	if ($options[3] >=3) { $options[3]=0; } }
    elsif($key=~/t/i) { 
	if ($options[1] == 0) { $options[1]=1; }
	else { $options[1]=0; } }
    # Seeking
    elsif($key=~/x/i) { $zsize=0; $z=$zmin;
    	if (($options[1] > 0) and ($tsize <= ($tres-5))) { $t += 5*($tmax-$tmin)/($tres-1); $tsize=$tsize+5; }
	elsif ($tsize < $tres) { $t += ($tmax-$tmin)/($tres-1); $tsize++; } } 
    elsif($key=~/y/i) { $zsize=0; $z=$zmin; 
    	if (($options[1] > 0) and ($tsize >= 5)) { $t -= 5*($tmax-$tmin)/($tres-1); $tsize=$tsize-5; }
	elsif ($tsize > 0) { $t -= ($tmax-$tmin)/($tres-1); $tsize--; } } 
    # resolution (! BUGGY !)
    elsif($key=~/u/i){ $t=$tmin; $z=$zmin; $xres=int($xres*1.1+0.9); $zres=int($zres*1.1+0.9); }
    elsif($key=~/z/i){ $t=$tmin; $z=$zmin; $xres=int($xres*0.91+0.2); $zres=int($zres*0.91+0.2); }
    elsif($key=~/j/i){ $t=$tmin; $z=$zmin; $tsize=0; $zsize=0; $tres=int($tres*1.1+0.9); }
    elsif($key=~/h/i){ $t=$tmin; $z=$zmin; $tsize=0; $zsize=0; $tres=int($tres*0.91+0.2); }
    # rotation
    elsif($key=~/w/i){ glRotatef(3, 1, 0, 0); }
    elsif($key=~/s/i){ glRotatef(-3, 1, 0, 0); }
    elsif($key=~/a/i){ glRotatef(3, 0, 1, 0); }
    elsif($key=~/d/i){ glRotatef(-3, 0, 1, 0); }
    # translation
    elsif($key=~/\ü/i){ glTranslatef(0, 0.5, 0); }
    elsif($key=~/\ä/i){ glTranslatef(0, -0.5, 0); }
    elsif($key=~/\ö/i){ glTranslatef(-0.5, 0, 0); }
    elsif($key=~/\$/i){ glTranslatef(0.5, 0, 0); }
    # Scaling
    elsif($key=~/r/i){ glScalef(1.1,1.1,1.1); }
    elsif($key=~/e/i){ glScalef(0.91,0.91,0.91); }

    # repaint the window
#    display(); 
idle();
}


sub getheader{
    my ($width,$height) = @_;
    my ($header);

    $header =  pack("s",hex("4d42"));	        #signature
    $header .= pack("i",$width*$height*3+hex(36));#size (inc header)
    $header .= pack("s",0);			#reserved
    $header .= pack("s",0);			#reserved
    $header .= pack("i",hex(36));		#offset
    $header .= pack("i",40);		        #size of BITMAPINFOHEADER structure, must be 40
    $header .= pack("i",$width);		#width
    $header .= pack("i",$height);		#hight
    $header .= pack("s",1);			#number of planes in the image, must be 1
    $header .= pack("s",24);	                #bites per pixel
    $header .= pack("i",0);			#compression type (0=none, 1=RLE-8, 2=RLE-4)
    $header .= pack("i",$width*$height*3);	#size of image data
    $header .= pack("i",0);			#horizontal resolution in pixels per meter (unreliable)
    $header .= pack("i",0);			#vertical resolution in pixels per meter (unreliable)
    $header .= pack("i",0);			#number of colors in image, or zero
    $header .= pack("i",0);			#number of important colors, or zero

    return $header;
}


sub screenshot {
    my $num = 1;
    my $i;
    $num++ while(-f "image$num.bmp");

    if(open(IMAGE,">image$num.bmp")){
        print IMAGE getheader($width,$height);
        my @pixels=glReadPixels_p(0, 0,$width,$height, GL_RGB,GL_UNSIGNED_INT);
        #{print (IMAGE pack("B*", $i )); }for $i (@pixels);
        for $i (0..(($#pixels-1)/3)){
            my ($red, $green, $blue) = ($pixels[$i*3],$pixels[$i*3+1],$pixels[$i*3+2]);
            print IMAGE pack("B B B",$blue,$green,$red); }
        #for $pixel (@pixels){ print IMAGE pack ("B*",$pixel);}
        close(IMAGE);
    }
}