Java – Page 2

More progress towards my project

I’ve been doing odds and sods today.

Play a list of videos on a continuous loop full screen. By using libvlc and the Java wrapper I’ve finally got a full screen player working in less than 60 lines of code which plays a list of video files.
Write a server and test over the internet. Using just a Java server, the initial test worked which was to accept a connection and send “Hello world!” back. Now that it is running I can expand the server with all the functionality I require. This will be handling the back-end database, media and installations.
Define a KISS (Keep It Simple Stupid) database for handling devices and media.

To do:

Write a mobile Android app to manage the setup of devices and assigning play lists. This is going to be a big one and a lot of work and I need to be on site when setting up devices and getting them playing without glitches.
Expand on the software for the media player so that it can update itself from the server with not only media updates, but also software updates.
Run an outside test live over the internet and update the playlist.
Get more experience with Blender and video creation. For the most part, I’m more than capable of producing the videos in approximately an hour for everything I need. The more I get familiar with Blender then I can add more effects to the videos which will be a bonus.
Bully test the server. I already have someone on hand that can test the servers integrity and stability. Pen-testing the server will give me some good pointers to how to make it more secure. I’m also considering the 2 way login.

That’s the plan for the next couple of weeks. Just so long as I get some free time I can move along quite quickly with this with the exception of the bully testing and updating.

Right now, things are looking almost bullet proof. Fingers crossed.

EDIT:

I forgot to add the VPS (Virtual Private Server)

Parallax3D WebGL

This is proving to be easier than I thought.

The Eclipse GWT project was setup. The parallax3D jar library added. A test AnimatedScene class with some basic geometry tests done. Spin a few of them around.

That’s me done for tonight. Got work in the morning.

I’m hoping I can load in Blender models, or even .OBJ models. If not, I’ll figure something out. Also 3D text I need.

No screeny yet cos of screen tearing.

Tonight I had a full on plan to get my own VPS (Linux based) and setup a Tomcat server ready for my WebGL personal project showcase. I’m planning on porting some old school samples from years ago from both IrrLicht and Dark Basic Pro.

So far, I’ve not made a start as the missus passed her CBT today (Motorbike Compulsory Basic Training) and she is way over excited.

VPS and Tomcat are still in progress.

I also plan on studying this WebAsm too for much faster rendering.

To start with I will be using Parallax3D for GWT which I’ve played around with a few times before. I finally decided on Parallax3D after giving up on LibGDX (which is very good and easy), and CopperLicht (which I don’t like using Javascript).

If it chills out tonight, which is highly unlikely, then I’ll make a start.

WebGL 3D

After faffing about with CopperCube and CopperLicht, which is fun to play around with, I’ve found it quite restricting for the type of demonstrations that I want to do. So I’ve decided to head on back to Parallax3D, bypassing the urge to play with LibGDX again.

The reason for dumping CopperLicht is simple. I don’t like Javascript at all. With GWT, it is rare I need to use JSNI with it.

LibGDX is good but each LibGDX project has to be a complete GWT module in itself, which means copying over all the GWT stuff again. It probably is likely that I could integrate it into a GWT project and I might try it at some point.

However, Parallax3D just appears to have everything and is a simple Jar file which is added to a GWT project.

So… It’s finding out what mesh files (hopefully wavefront OBJ’s as well) and I’ll be up and running if the weather is bad this weekend.

I also need to FTP this site as my homes Sky router isn’t working with the DNS service.

Enough of this. Time to setup a project on my lappy.

Java programming

After just over 3 years of programming in Java, I still haven’t sussed out how to actually open up a basic IDE and start a simple UI project from scratch.

This I know from installing Netbeans. Which I’ve used before to create a dedicated server so that client devices can receive images created using Java AWT libraries. That was easy, create a TCP listening thread, accept connections, return renderings of bitmaps in compressed PNG format. Easy.

I’ve also created (which was a UI app) a program that sniffs the UDP broadcast of the IPTV/Digital Signage server (which I wrote), and opens up a custom web interface from the server without knowing the IP address. That was easy with the help of a couple of references from the web. It turned out to be quite a small program in the end and hardly any effort in it.

Even after Android development, writing games and even using FFMpeg to write a media player using the NDK.

I simply just wanted to write (using the accumulated knowledge of Java) a simple multi window/dialog application on my laptop. Wow… It still amazes me how I got through all the previous software developing. Maybe on an evening, I’m just not that focused. But I’m not giving in.

Java may not have the power of C, but it does have a lot that can be used as I’ve mentioned above. I’m finding it simple to handle threading and AWT bitmaps, etc. All I need now is to be able to setup up a display in a window (GL or raster, whichever is the quickest to begin with) and I’ll be happy.

Qt is simple enough for both openGL and normal UI stuff. So now I want to do the same with Java. So far without the UI stuff, I can run anything, ie server side from Java, but UI stuff I’ll just have to persevere with.

I’ll get there. Nighttime coding was something I always used to do. Going to bed when I realised the sun was poking its head up in the morning.

It’s been a while

Yes, most definitely it has been some time since I last posted anything on my blog. That’s because this last month I have hardly had any real chill time to myself. Well, I have had some, but it never lasts for long enough.

Anyway, I’ve still been faffing about. I recently purchased CopperCube so that I could delve deeper into WebGL. Plus I’m familiar with Irrlicht, and CopperLicht makes working with 3D graphics a doddle.

I’ve also found that I can actually call myself a full-stack developer considering recent projects I’ve been working on. One project involves a C/C++ TCP/UDP server for communications, A Java TCP server to use Java AWT graphics, GWT for a web interface instead of installing software. The server does many things, too many to mention, but I’m well chuffed with it.

Setting up the server involves freshly installing Linux. Then installing Apache Tomcat. Making a few modifications to the system and then installing the software.

Device connect on the network via ethernet or wifi and will automatically detect the location of the server because of the UDP heart beat. Clever stuff really. Probably not, but all the same, it works great.

I’ve also played around with having a home TCP server which can be made use of from my mobile phone while I am out, my tablet or a PC, as well as a GWT web interface.

After playing around with all of this, there’s lot’s more I want to play with. Maybe Vaadin or similar. Move on to desktop 3D graphics again instead of openGLES 2.

I’ve also finally got myself an i7 laptop with nVidia graphics. Cheap off eBay! So I can develop on the go. That’s if the battery is good in it.

There’s other things over this last month that have tickled my fancy, but I won’t mentioned that here. Tempting though.

Hopefully this weekend I will have a long one as I’m booking Friday and Monday off because I seriously need to relax a little.

Until next time…

WebGL engine test

Yesterday I played around with a webGL engine and added it to my home hosted servers website. So it will not be available to view all the time.

wlgfx@home

Here’s a screenshot of it running in the Chrome browser:

wlgfxathomejunglescene

When you write something really awesome

As it say on the page, thinking of data in C++ takes some time and some mental planning. Java with its quirks, I finally think I’ve got the knack of it.

Glorious Java inheritance

WLGfx@home updated

Click here: WLGfx@home to view my PCs hosted site.

If it doesn’t load up then my home PC is not switched on.

There’s still quite a bit to do to this site, especially to do with the 3D stuff. I’ve got to setup a decent scene to show off with. Some cool shaders and some decent meshes.

Online GL shader editor

Just so I don’t lose or forget about it, I’ve found a very handy online openGL shader editor…

ShaderFrog

From basic shaders including texturing and lighting right up to procedural shaders and more.

All I need now is to run a sample project in Qt to test out some of these and then transfer them to GWT and Parallax. Good stuff can now be done.

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Perfect Maze now working

After a thorough going over of the code, I’ve managed to get this one working. Although painfully slow, at least it works. In the future I will be looking at other algorithms which are much faster. I only remembered this one from a long time ago so I just thought I’d have a go on my own without any help with implementing it.

// File: generate.agc
// Created: 19-09-21

/*
	Attempting to generate a maze using a decent algorithm.
	Unfortunately this particular algorith is painfully slow,
	but for the time being, it does work.
*/

type MAZE
	seed as integer
	wid as integer
	hgt as integer
	maze as integer[0,0]
endtype

function maze_get_odd_random(max as integer)
	val = random(0, ((max - 2) / 2)) * 2 + 1
endfunction val

function maze_not_visited(obj ref as MAZE, xpos, ypos)
	val = obj.maze[ypos, xpos]
endfunction val

/*
	The width and height have to be even numbers.
	NB: In AGK this means 0 to width (as even) for example
		NOT 0 to width - 1
*/

function maze_gen(obj ref as MAZE, wid as integer, hgt as integer, seed as integer)
	obj.seed = seed
	
	SetRandomSeed(seed)
	
	obj.wid = wid
	obj.hgt = hgt

	/*
		Wierd way of assigning a multidimensional array
		Assign the first dimensions length
		And then assign the length of each separate part
		ie.
		a[0].length = 5 (giving a[0,4])
		is not the same as
		a[1].length = 10 (which gives a[1,9])
		
		Also, AGK arrays end with the value assigned.
		ie. length is 10 so the array goes from 0 to 10
		instead of 0 to 9.
	*/
	
	obj.maze.length = hgt

	for c = 0 to hgt
		obj.maze[c].length = wid
		
		for x = 0 to wid
			obj.maze[c, x] = 1
		next
	next c
	
	/*
		If I remember correctly, I choose a random cell.
		But, it has to be, erm, ODD or EVEN???
		I will find out...
		
		It has to be odd.
	*/
	
	currentx = maze_get_odd_random(wid)
	currenty = maze_get_odd_random(hgt)
	
	// set position to 0
	
	obj.maze[currenty, currentx] = 0
	
	done = 0
	
	repeat
		
		// iterations to run through (might increase)
		for route = 0 to 63
			
			/*
				Basically direction is UP, DOWN, LEFT or RIGHT
			*/
			
			direction = random(0, 3)
			
			select direction
				case 0:
					if currenty - 2 > 0
						if maze_not_visited(obj, currentx, currenty - 2)
							obj.maze[currenty - 2, currentx] = 0 // clear path
							obj.maze[currenty - 1, currentx] = 0 // between
						endif
						dec currenty, 2
					endif
				endcase
				
				case 1:
					if currenty + 2 < hgt
						if maze_not_visited(obj, currentx, currenty + 2)
							obj.maze[currenty + 2, currentx] = 0
							obj.maze[currenty + 1, currentx] = 0
						endif
						inc currenty, 2
					endif
				endcase
				
				case 2:
					if currentx - 2 > 0
						if maze_not_visited(obj, currentx - 2, currenty)
							obj.maze[currenty, currentx - 2] = 0
							obj.maze[currenty, currentx - 1] = 0
						endif
						dec currentx, 2
					endif
				endcase
				
				case 3:
					if currentx + 2 < wid
						if maze_not_visited(obj, currentx + 2, currenty)
							obj.maze[currenty, currentx + 2] = 0
							obj.maze[currenty, currentx + 1] = 0
						endif
						inc currentx, 2
					endif
				endcase
			endselect
		next
		
		/*
			Print this mazes iteration (just for testing)
		*/
		
		Print( ScreenFPS() )
		maze_print(obj)
		print("Calculating...")
		sync()
		
		/*
			Check if maze is done (the silly bit)
		*/
		
		done = 0
		
		for h = 1 to hgt - 1 step 2
			for w = 1 to wid - 1 step 2
				if obj.maze[h, w] = 1
					done = 1
					exit // quick exit if not done
				endif
			next
			if done = 1 then exit
		next
		
	until done = 0
	
endfunction obj

function maze_print(obj ref as MAZE)
	print (obj.wid)
	print (obj.hgt)
	//print (random(0, 2) - 1) // HUH
	
	for h = 0 to obj.hgt
		s as string = ""
		for w = 0 to obj.wid
			if obj.maze[h, w] = 1 then s = s + "#" else s = s + " "
		next
		print (s)
	next
endfunction

Hmm… Almost…

// File: generate.agc
// Created: 19-09-21

/*
	Attempting to generate a maze using a decent algorithm
*/

type MAZE
	seed as integer
	wid as integer
	hgt as integer
	maze as integer[0,0]
endtype

function maze_get_odd_random(max as integer)
	val = random(0, max / 2) + 1
endfunction val

function maze_not_visited(obj as MAZE, xpos, ypos)
	val = obj.maze[ypos, xpos]
endfunction val

/*
	The width and height have to be even numbers.
	NB: In AGK this means 0 to width (as even) for example
		NOT 0 to width - 1
*/

function maze_gen(obj ref as MAZE, wid as integer, hgt as integer, seed as integer)
	obj.seed = seed
	
	//SetRandomSeed(seed)
	
	obj.wid = wid
	obj.hgt = hgt

	/*
		Wierd way of assigning a multidimensional array
		Assign the first dimensions length
		And then assign the length of each separate part
		ie.
		a[0].length = 5 (giving a[0,4])
		is not the same as
		a[1].length = 10 (which gives a[1,9])
		
		Also, AGK arrays end with the value assigned.
		ie. length is 10 so the array goes from 0 to 10
		instead of 0 to 9.
	*/
	
	obj.maze.length = hgt

	for c = 0 to hgt
		obj.maze[c].length = wid
		
		for x = 0 to wid
			obj.maze[c, x] = 1
		next
	next c
	
	/*
		If I remember correctly, I choose a random cell.
		But, it has to be, erm, ODD or EVEN???
		I will find out...
		
		It has to be odd.
	*/
	
	currentx = maze_get_odd_random(wid)
	currenty = maze_get_odd_random(hgt)
	
	// set position to 0
	
	obj.maze[currenty, currentx] = 0
	
	done = 0
	
	repeat
		
		// iterations to run through (might increase)
		for route = 0 to 3
			
			/*
				Basically direction is UP, DOWN, LEFT or RIGHT
			*/
			
			direction = random(0, 3)
			
			select direction
				case 0:
					if maze_not_visited(obj, currentx, currenty - 2) and currenty - 2 > 0
						obj.maze[currenty - 2, currentx] = 0 // clear path
						obj.maze[currenty - 1, currentx] = 0 // between
						currenty = currenty - 2
					endif
				endcase
				
				case 1:
					if maze_not_visited(obj, currentx, currenty + 2) and currenty +2 < hgt
						obj.maze[currenty + 2, currentx] = 0
						obj.maze[currenty + 1, currentx] = 0
						currenty = currenty + 2
					endif
				endcase
				
				case 2:
					if maze_not_visited(obj, currentx - 2, currenty) and currentx - 2 > 0
						obj.maze[currenty - 2, currentx] = 0
						obj.maze[currenty - 1, currentx] = 0
						currentx = currentx - 2
					endif
				endcase
				
				case 3:
					if maze_not_visited(obj, currentx + 2, currenty) and currentx + 2 < wid
						obj.maze[currenty, currentx + 2] = 0
						obj.maze[currenty, currentx + 1] = 0
						currentx = currentx + 2
					endif
				endcase
			endselect
		next
		
		/*
			Check if maze is done (the silly bit)
		*/
		
		for h = 1 to hgt - 1 step 2
			for w = 1 to wid - 1 step 2
				if obj.maze[h, w] = 1
					done = 1
					exit // quick exit if not done
				endif
			next
			if done = 1 then exit
		next
		
	until done = 0
	
endfunction obj

function maze_print(obj ref as MAZE)
	print (obj.wid)
	print (obj.hgt)
	print (random(0, 2) - 1) // HUH
	
	for h = 0 to obj.hgt
		s as string = ""
		for w = 0 to obj.wid
			if obj.maze[h, w] = 1 then s = s + "#" else s = s + " "
		next
		print (s)
	next
endfunction

Not quite working… Need a nap… Not well…

A Perfect Maze

So I got an algorithm done last week that produced a perfect maze. Unfortunately though, I wiped my 2 x 1Tb SSD’s on my PC and didn’t back up the code.

So I am starting again.

(I’m not too good by the way, so I am documenting this)

I didn’t want a recursive algorithm because I think that on low end architecture this would be bad for memory usage. This meant that the algorithm would possibly be slower. For a 40 by 40 maze it would still be instant, even though there was a silly check in there.

Here goes. (back soon with some snippets)

I’m using AGK and will port everything to C.

Back to these C++ tuples

Okay, now that Christmas and New Year is finally over and I’ve got pockets like a white eared elephant, I decided to have another blast at these tuple things because they were doing my head in.

All along I’ve been thinking that a class/struct would be much better. In most cases I would be right, but then I thought, “Hang on, this is C++. Let me check if I can return a tuple from a function.”

Hey, turns out I could.

#include <cstdlib>
#include <iostream>
#include <tuple>

using namespace std;

auto get_tuple(string name) {
    return make_tuple(name, 1);
}

int main(int argc, char** argv) {
    auto t3 = get_tuple("FOO");
    auto t4 = get_tuple("BAR");
    
    cout << get<0>(t3) << endl << get<0>(t4) << endl;
    
    return 0;
}

And voila, just like that I can now return multiple values from a function.

The one thing you have to be careful of is the setup. A typo mistake or a type mistake can and will cost hours of debugging so be wary of things like this:

    auto t1 = std::make_tuple("foo", 1, 2);
    auto t2 = std::make_tuple("bar", 1.0, 2);

Now even if I added to the first tuple “foo”, 1f, 2, this would not match the second as the second tuple uses a double value. A pain for debugging.

Just the fact you can return multiple values of data without having to define a complete struct or class is actually quite a nice addition.

I have done some research into tuples now and found that these use cases are good, but for larger data, it is so much better even to still use a struct/class because with the above examples you still are having to use index values to access the data items. Where as a struct/class, the data items are named.

Although this however can be overcome by using enums, larger tuples are very likely better off being converted to a struct/class.

Even after 35+ years of programming I’m still learning.

Time to move onto something else… Bigger…

Some C++ tests

Well, after a while of faffing about with other things, I thought I’d go through some of the new features of C++17 and just a quick play about I found some very interesting new features.

#include <cstdlib>
#include <iostream>
#include <string>
#include <vector>
#include <tuple>

using namespace std;

int main(int argc, char** argv) {
    vector<string> strings = {
        "Hello",
        "World",
        "This",
        "is",
        "the",
        "best",
        "I",
        "can",
        "do"
    };
    
    for (string str: strings) { // I now know
        cout << str << endl;
    }
    
    cout << strings.size() << endl;
    
    // https://www.geeksforgeeks.org/tuples-in-c/
    // makes it more interesting with tuple_cat
    
    auto mytuple1 = make_tuple("triangle1", 't', 10, 15, 20); // interesting...
    auto mytuple2 = make_tuple("triangle2", 'b', 1, 2, 3);
    cout << get<0>(mytuple1) << endl;
    mytuple1.swap(mytuple2);
    cout << get<0>(mytuple1) << endl;
    cout << tuple_size<decltype(mytuple1)>::value << endl;

    return 0;
}

First off the std<vector> initialisation can now be done as it is with Java, but more interestingly is the for loop which works with any class list. That makes life so much easier for C++ handling data.

The next bit was the tuples. For some reason I always associated tuples with a set of 3 items. But after this… This allows for a quick, and maybe dirty way, of avoiding setting up a new class to handle short bursts of data. Very simple.

Now I’m going to play around with some more C++17 features. I may end up moving completely back to C++ and away from Java again.

EDIT:

The output:

Hello
World
This
is
the
best
I
can
do
9
triangle1
triangle2
5

RUN FINISHED; exit value 0; real time: 0ms; user: 0ms; system: 0ms

Java ‘long’ to C++ ‘int64_t’

Hallelujah!

For the last two weeks I’ve had an intermittent problem with my C++ version of the crypto socket client, and tonight I finally cracked the issue.

The Java version is using ‘long’ for doing it’s calculations and the C++ version was using a 64 bit integer, which should have been fine until tonight I realised that Java was using its ‘long’ values as signed. Whereas I had been using ‘uint64_t’ in the C++ version.

This caused the C++ version to work once in every 5 to 10 tries. Just by removing the unsigned, it now works flawlessly.

Phew! Now I can blitz the rest…

^{(Yep, it has been a while since the last post)}

All setup here nicely

Been busy working on my secret project.

csnorwood.com

It was tough to accept the change from my old website (wlgfx) to this new one (csnorwood), but I couldn’t ignore the benefits.

Yes, this is going to affect the search engines for some time but I’m used to that. I can still slowly build stuff in the meantime while the web crawlers do there stuff.

It’s highly unlikely that the the old web address is even going to link back to this new one, but what the hell. Time to move onward and upwards.

Rewrite from Java to C++

Okay, so my server is currently running on Java and makes use of DataOutputStream and DataInputStream. And whilst I’m on a rewrite, I need to wrap those into C++.

Which I thought might be a tad difficult…

It turns out that Linux automatically handles UTF-8 strings out of the box, so sending and receiving string is of no consequence. Which was one of my main worries before I looked into everything else which slowed down the transition. Java’s DataOutputStream writes it UTF-16 strings as UTF-8 strings over the wire. That’s that problem solved.

The other problem was wrapping the socket connection. Sorted. Easily done by returning the error status on every call and handling the active status of the socket.

The last problem was wrapping the Java functions for sending a Long, Int, Byte, String, etc… These need to be in network byte order, which is not little endian. I’m just going through that now.

Oh yeah, encryption using a Cryptographic Secure Pseudo Random Number Generator. Done and implemented to match perfectly the Java version… For now.

So hopefully soon, I’ll be able to test run this wrapper ready for a production run.

Amazing feeling

“I feel almost like a god!”

To have my own software running in the cloud and being able to serve its purpose, ‘feels good’.

Yes, I’ve had one of those moments of personal successful achievements accomplished.

Or something like that.

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Category: Java