#!/usr/bin/perl -w
# This code was created by Jeff Molofee '99
# (ported to SDL by Sam Lantinga '2000)
# (ported to Perl/SDL by Wayne Keenan '2000)
#
# If you've found this code useful, please let me know.
#
# Visit me at www.demonews.com/hosted/nehe

use strict;
use Getopt::Long;
use Data::Dumper;
use Benchmark;

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

my $arg_screen_width  = 640;
my $arg_screen_height = 512;
my $arg_fullscreen    = 0;

GetOptions(
	"width:i"     => \$arg_screen_width,
	"height:i"    => \$arg_screen_height,
	"fullscreen!" => \$arg_fullscreen,

) or die $!;

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

my $light = 0;

my $xrot   = 0; # x rotation
my $yrot   = 0; # y rotation
my $xspeed = 0; # x rotation speed
my $yspeed = 0; # y rotation speed

my $z = -5.0;   # depth into the screen.

my $filter = 1; # Which Filter To Use (nearest/linear/mipmapped) */
my $blend  = 1;

print STDERR "Use b to toggle blend, page up/down to zoom, and arrow keys to rotate\n";

main();
exit;

sub main {
	my $done          = 0;
	my $vidmode_flags = SDL_OPENGL;

	$vidmode_flags |= SDL_FULLSCREEN if $arg_fullscreen;

	my $app = SDLx::App->new(
		-title  => "Jeff Molofee's GL Code Tutorial ... NeHe '99",
		-icon   => "icon.png",
		-flags  => $vidmode_flags,
		-width  => $arg_screen_width,
		-height => $arg_screen_height,
		-opengl => 1,
	);

	SDL::ShowCursor(0);

	my $event = SDL::Event->new;
	$event->set( SDL_SYSWMEVENT, SDL_IGNORE );

	InitGL( $arg_screen_width, $arg_screen_height );

	glEnable(GL_BLEND); # Turn Blending On
	glEnable(GL_LIGHTING);
	glDisable(GL_DEPTH_TEST); # Turn Depth Testing Off

	while ( not $done ) {

		DrawGLScene();

		$app->sync();

		$event->pump;
		$event->poll;

		$done = 1 if ( $event->type == SDL_QUIT );

		if ( $event->type == SDL_KEYDOWN ) {
			my $key = $event->key_sym;

			$done = 1 if ( $key == SDLK_ESCAPE );

			if ( $key == SDLK_f ) {
				printf( "Filter was: %d\n", $filter );
				$filter = 1 + ( ($filter) % 3 );
				printf( "Filter is now: %d\n", $filter );
				$app->delay(100);
			}
			if ( $key == SDLK_b ) {
				printf( "Blend was: %d\n", $blend );
				$blend = $blend ? 0 : 1;
				printf( "Blend is now: %d\n", $blend );
				$app->delay(100);
				if ($blend) {
					glEnable(GL_BLEND); # Turn Blending On
					glEnable(GL_LIGHTING);
					glDisable(GL_DEPTH_TEST); # Turn Depth Testing Off
				} else {
					glDisable(GL_BLEND);      # Turn Blending Off
					glDisable(GL_LIGHTING);
					glEnable(GL_DEPTH_TEST);  # Turn Depth Testing On
				}
			}

			#bit lax:
			$z -= 0.02 if ( $key == SDLK_PAGEUP );
			$z      += 0.02 if ( $key == SDLK_PAGEDOWN );
			$xspeed += 0.02 if ( $key == SDLK_UP );
			$xspeed -= 0.02 if ( $key == SDLK_DOWN );
			$yspeed -= 0.01 if ( $key == SDLK_LEFT );
			$yspeed += 0.01 if ( $key == SDLK_RIGHT );

		}
	}
}

#########################################################################
#Pretty much in original form, but 'Perlised'

sub InitGL {
	my ( $Width, $Height ) = @_;

	glViewport( 0, 0, $Width, $Height );

	LoadGLTextures(); # Load The Texture(s)

	glEnable(GL_TEXTURE_2D); # Enable Texture Mapping

	glClearColor( 0.0, 0.0, 0.0, 0.0 ); # This Will Clear The Background Color To Black
	glClearDepth(1.0);                  # Enables Clearing Of The Depth Buffer
	glDepthFunc(GL_LESS);               # The Type Of Depth Test To Do
	glEnable(GL_DEPTH_TEST);            # Enables Depth Testing
	glShadeModel(GL_SMOOTH);            # Enables Smooth Color Shading

	glMatrixMode(GL_PROJECTION);
	glLoadIdentity();                   # Reset The Projection Matrix

	gluPerspective( 45.0, $Width / $Height, 0.1, 100.0 ); # Calculate The Aspect Ratio Of The Window

	glMatrixMode(GL_MODELVIEW);

	my $LightAmbient = [ 0.5, 0.5, 0.5, 1.0 ];            # white ambient light at half intensity (rgba) */

	my $LightDiffuse = [ 1.0, 1.0, 1.0, 1.0 ];            # super bright, full intensity diffuse light. */

	my $LightPosition = [ 0.0, 0.0, 2.0, 1.0 ];           # position of light (x, y, z, (position of light)) */

	#setup light number 1
	glLight( GL_LIGHT1, GL_AMBIENT,  @$LightAmbient );    # add lighting. (ambient)
	glLight( GL_LIGHT1, GL_DIFFUSE,  @$LightDiffuse );    # add lighting. (diffuse).
	glLight( GL_LIGHT1, GL_POSITION, @$LightPosition );   # set light position.
	glEnable(GL_LIGHT1);                                  # turn light 1 on.
	                                                      #/* setup blending */
	glBlendFunc( GL_SRC_ALPHA, GL_ONE );                  # Set The Blending Function For Translucency
	glColor( 1.0, 1.0, 1.0, 0.5 );

}

# The main drawing function.
sub DrawGLScene {
	glClear( GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT ); # Clear The Screen And The Depth Buffer
	glLoadIdentity();                                     # Reset The View

	glTranslate( 0.0, 0.0, $z );                          # move z units out from the screen.

	glRotate( $xrot, 1.0, 0.0, 0.0 );                     # Rotate On The X Axis
	glRotate( $yrot, 0.0, 1.0, 0.0 );                     # Rotate On The Y Axis

	glBindTexture( GL_TEXTURE_2D, $filter );              # choose the texture to use.

	glBegin(GL_QUADS);                                    # begin drawing a cube

	# Front Face (note that the texture's corners have to match the quad's corners)
	glNormal( 0.0, 0.0, 1.0 );                            # front face points out of the screen on z.
	glTexCoord( 0.0, 0.0 );
	glVertex( -1.0, -1.0, 1.0 );                          # Bottom Left Of The Texture and Quad
	glTexCoord( 1.0, 0.0 );
	glVertex( 1.0, -1.0, 1.0 );                           # Bottom Right Of The Texture and Quad
	glTexCoord( 1.0, 1.0 );
	glVertex( 1.0, 1.0, 1.0 );                            # Top Right Of The Texture and Quad
	glTexCoord( 0.0, 1.0 );
	glVertex( -1.0, 1.0, 1.0 );                           # Top Left Of The Texture and Quad

	# Back Face
	glNormal( 0.0, 0.0, -1.0 );                           # back face points into the screen on z.
	glTexCoord( 1.0, 0.0 );
	glVertex( -1.0, -1.0, -1.0 );                         # Bottom Right Of The Texture and Quad
	glTexCoord( 1.0, 1.0 );
	glVertex( -1.0, 1.0, -1.0 );                          # Top Right Of The Texture and Quad
	glTexCoord( 0.0, 1.0 );
	glVertex( 1.0, 1.0, -1.0 );                           # Top Left Of The Texture and Quad
	glTexCoord( 0.0, 0.0 );
	glVertex( 1.0, -1.0, -1.0 );                          # Bottom Left Of The Texture and Quad

	# Top Face
	glNormal( 0.0, 1.0, 0.0 );                            # top face points up on y.
	glTexCoord( 0.0, 1.0 );
	glVertex( -1.0, 1.0, -1.0 );                          # Top Left Of The Texture and Quad
	glTexCoord( 0.0, 0.0 );
	glVertex( -1.0, 1.0, 1.0 );                           # Bottom Left Of The Texture and Quad
	glTexCoord( 1.0, 0.0 );
	glVertex( 1.0, 1.0, 1.0 );                            # Bottom Right Of The Texture and Quad
	glTexCoord( 1.0, 1.0 );
	glVertex( 1.0, 1.0, -1.0 );                           # Top Right Of The Texture and Quad

	# Bottom Face
	glNormal( 0.0, -1.0, 0.0 );                           # bottom face points down on y.
	glTexCoord( 1.0, 1.0 );
	glVertex( -1.0, -1.0, -1.0 );                         # Top Right Of The Texture and Quad
	glTexCoord( 0.0, 1.0 );
	glVertex( 1.0, -1.0, -1.0 );                          # Top Left Of The Texture and Quad
	glTexCoord( 0.0, 0.0 );
	glVertex( 1.0, -1.0, 1.0 );                           # Bottom Left Of The Texture and Quad
	glTexCoord( 1.0, 0.0 );
	glVertex( -1.0, -1.0, 1.0 );                          # Bottom Right Of The Texture and Quad

	# Right face
	glNormal( 1.0, 0.0, 0.0 );                            # right face points right on x.
	glTexCoord( 1.0, 0.0 );
	glVertex( 1.0, -1.0, -1.0 );                          # Bottom Right Of The Texture and Quad
	glTexCoord( 1.0, 1.0 );
	glVertex( 1.0, 1.0, -1.0 );                           # Top Right Of The Texture and Quad
	glTexCoord( 0.0, 1.0 );
	glVertex( 1.0, 1.0, 1.0 );                            # Top Left Of The Texture and Quad
	glTexCoord( 0.0, 0.0 );
	glVertex( 1.0, -1.0, 1.0 );                           # Bottom Left Of The Texture and Quad

	# Left Face
	glNormal( -1.0, 0.0, 0.0 );                           # left face points left on x.
	glTexCoord( 0.0, 0.0 );
	glVertex( -1.0, -1.0, -1.0 );                         # Bottom Left Of The Texture and Quad
	glTexCoord( 1.0, 0.0 );
	glVertex( -1.0, -1.0, 1.0 );                          # Bottom Right Of The Texture and Quad
	glTexCoord( 1.0, 1.0 );
	glVertex( -1.0, 1.0, 1.0 );                           # Top Right Of The Texture and Quad
	glTexCoord( 0.0, 1.0 );
	glVertex( -1.0, 1.0, -1.0 );                          # Top Left Of The Texture and Quad

	glEnd();                                              # done with the polygon.

	$xrot += $xspeed;                                     # X Axis Rotation
	$yrot += $yspeed;                                     # Y Axis Rotation

}

sub LoadGLTextures {

	# Load Texture

	my ( $pixels, $width, $height, $size ) = ImageLoad("Data/glass.bmp");

	# Create Texture

	glGenTextures(3);

	# texture 1 (poor quality scaling)
	glBindTexture( GL_TEXTURE_2D, 1 ); # 2d texture (x and y size)

	glTexParameter( GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST ); # cheap scaling when image bigger than texture
	glTexParameter( GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST ); # cheap scaling when image smalled than texture

	# 2d texture, level of detail 0 (normal), 3 components (red, green, blue), x size from image, y size from image,
	# border 0 (normal), rgb color data, unsigned byte data, and finally the data itself.
	#glTexImage2D(GL_TEXTURE_2D, 0, 3, image1->w, image1->h, 0, GL_RGB, GL_UNSIGNED_BYTE, image1->pixels);

	glTexImage2D( GL_TEXTURE_2D,
		0,                                                              #level (0 normal, heighr is form mip-mapping)
		3,                                                              #internal format (3=GL_RGB)
		$width, $height,
		0,                                                              # border
		GL_RGB,                                                         #format RGB color data
		GL_UNSIGNED_BYTE,                                               #unsigned bye data
		$pixels
	);                                                                  #ptr to texture data

	# texture 2 (linear scaling)
	glBindTexture( GL_TEXTURE_2D, 2 );                                  # 2d texture (x and y size)
	glTexParameter( GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR );  # scale linearly when image bigger than texture
	glTexParameter( GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR );  # scale linearly when image smalled than texture
	   #glTexImage2D(GL_TEXTURE_2D, 0, 3, image1->w, image1->h, 0, GL_RGB, GL_UNSIGNED_BYTE, image1->pixels);

	glTexImage2D( GL_TEXTURE_2D,
		0, #level (0 normal, heighr is form mip-mapping)
		3, #internal format (3=GL_RGB)
		$width, $height,
		0,                # border
		GL_RGB,           #format RGB color data
		GL_UNSIGNED_BYTE, #unsigned bye data
		$pixels
	);                    #ptr to texture data

	# texture 3 (mipmapped scaling)
	glBindTexture( GL_TEXTURE_2D, 3 ); # 2d texture (x and y size)
	glTexParameter( GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR ); # scale linearly when image bigger than texture
	glTexParameter( GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER,
		GL_LINEAR_MIPMAP_NEAREST
	); # scale linearly + mipmap when image smalled than texture
	   #glTexImage2D(GL_TEXTURE_2D, 0, 3, image1->w, image1->h, 0, GL_RGB, GL_UNSIGNED_BYTE, image1->pixels);

	glTexImage2D( GL_TEXTURE_2D,
		0, #level (0 normal, heighr is form mip-mapping)
		3, #internal format (3=GL_RGB)
		$width, $height,
		0,                # border
		GL_RGB,           #format RGB color data
		GL_UNSIGNED_BYTE, #unsigned bye data
		$pixels
	);                    #ptr to texture data

	# 2d texture, 3 colors, width, height, RGB in that order, byte data, and the data.
	gluBuild2DMipmaps( GL_TEXTURE_2D, 3, $width, $height, GL_RGB,
		GL_UNSIGNED_BYTE, $pixels
	);

	my $glerr = glGetError();
	die "Problem setting up 2d Texture (dimensions not a power of 2?)):" . gluErrorString($glerr) . "\n"
		if $glerr;

}

#somthing needs to keep the ref count alive for objects which represents data in C space (they have no ref count):
my @ref = ();

sub ImageLoad {
	my $filename = shift;

	my $surface = SDL::Surface->new( -name => $filename ); #makes use of SDL: BMP loader.

	my $width   = $surface->width();
	my $height  = $surface->height();
	my $bytespp = $surface->bytes_per_pixel();
	my $size    = $width * $height * $bytespp;

	my $surface_pixels = $surface->pixels();
	my $surface_size   = $width * $height * $surface->bytes_per_pixel();
	my $raw_pixels     = reverse $surface_pixels;

	#do a conversion (the pixel data is accessable as a simple string)

	my $pixels     = $raw_pixels;
	my $pre_conv   = $pixels;
	my $new_pixels = "";
	for ( my $y = 0; $y < $height; $y++ ) {
		my $y_pos = $y * $width * $bytespp;                       #calculate offset into the image (a string)
		my $row = substr( $pre_conv, $y_pos, $width * $bytespp ); #extract 1 pixel row
		$row =~ s/\G(.)(.)(.)/$3$2$1/gms;                         #turn the BMP BGR order into OpenGL RGB order;
		$new_pixels .= reverse $row;
	}

	$raw_pixels = $new_pixels;                                    #put transformed data into C array.
	push @ref, $raw_pixels, $surface;

	#we could have created another SDL surface frm the '$raw_pixel's... oh well.
	return ( $raw_pixels, $width, $height, $size );
}