Java vs C++ for 3D mesh building

A few days ago, playing around with LibGDX again I was getting back into 3D programming and created a very simple demo of a load of spheres and the camera rotating around the scene as below:

Which on my laptop ran just fine. It took about a second to generate all the meshes for each of the spheres.

Took bloody ages on my phone though, even though it’s a quad core 64 bit android phone. Approximately 5 to 8 seconds. Ouch.

None of this nonsense in C++ for starters. I know this from a very old project I was working back in the day. Procedural map generator. More about that here: PROCMAP DBP LINK

So for the last couple of days (actually on the evenings because of work), I’ve looked into creating a single sphere mesh and then duplicating it. In LibGdx

A minor problem to start off with is that a lot of LibGdx’s mesh generators have been deprecated and I don’t know how long for now, and I can’t find examples on how to use the new stuff. This would have made things easier, but that minor problem got bigger.

It seems that ModelBuilder only runs on the GL thread, so I tried the MeshBuilder. No luck there after trying to hunt info down on google, (Maybe google is hiding it from me :P) how to use the thing.

So I gave up, closed the project, might go back to it if the next step fails.

I’m waiting on a huge update from Qt. Oh! At this time it has finished downloading and updated.

The previous versions of Qt didn’t work with the latest Android SDK/NDK. Fingers crossed with this one…


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.


Variable names are important

For the last two days I’ve been working on decoding video frames and displaying them. The idea is to run against the system clock which I’ve had working everytime so far. This time though, I decided to make a general decoder so that I didn’t have to worry about FFMpeg’s video decoded format which up until now has always been YUV420 which I just had a GL using SL shader convert on the fly. Everything gets converted to an RGBA bitmap so I don’t have to worry about it.

Anyway, variable names…

I buffer up the frames and then test them against the current system clock for a frame that’s ready to be presented. I had two variable names, frame and frame_temp which are pretty innocent. Unfortunately though, and which I kept missing whilst going through the code, I was grabbing a pointer in frame_temp and testing it. If it fell below the current system time then it would then be assigned to frame. If there was a previous frame then it would be cleared from the buffer queue and added to the unused buffer queue.

Now this is what I missed.

Frame_temp is first used, frame is unitialised (actually null), the tests are done on frame_temp and if failed then just exits with a null pointer. Fair enough.

It was a “typo”.

Hidden between four lines of code using frame_temp I had used the variable frame instead (which is null to start with). When I accessed a method on that class it would crash.

The error message was very obscure and nothing on google search or anywhere else was any help.

My mistake…

Most of the time I rely on debug log outputs. And whilst running this code, everything was running just as it should. It’s hard to follow multiple threads in debug output.

Finally, I ran it through gdb which took me straight to the line of code where it crashed. The line right after the “typo”.

Lesson learnt…

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…

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…


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.