Thursday, 9 October 2008

The sorry state of symbian SDL

Probably noone of you care about the fact that there are four different versions of the SDL library for symbian based devices. When I was starting my S60 OpenTTD port there were only three. What has happened in between?

The first one was created by Hannu Viitala and was targetted at antique devices, had no sound support, etc... we're not that much interested in it.

The second one, maintained by Marcus Mertama, is an evolution of the previous, with support for S60 3rd edition devices (basically anything worth considering for purchase right now), sound and a lot of problems. More on that later.

The third one is, again, based on the previous one. It's used by anotherguest in his ScummVM port and focuses on wide device range support (including UIQ, touch screen, etc). Since it had the same problems as the second version, I didn't looked too deeply into it.

The fourth option is constantly fixed (or rather stripped down from features) by yours truly. There were several issues in Markus' version which really bothered me.

The first was support for S60v1 and S60v2.
  • If I'm going to modify the code, I have no way to test if the code works.
  • The platform is severely limited by screen resolution, processor speed, available RAM, lack of Open C and Open C++ or even by inability to use static variables.
  • The platform is dead.
So, drop it. Leave only S60v3.

The next big issue was resolution support. Or rather lack of it. The game resolution was always stretched to the phone's display resolution, which resulted in something that can be seen on the images below. The left one is original, the right one is scaled one. Horrible. And barely playable, thanks to ultra slow symbian blitting procedures.





My version does it right (or rather should be doing, I didn't actually checked it) by setting the right display orientation and by not stretching the display. This is one of things where my and other authors views differ. I don't accept the scaling, Marcus and anotherguest say that users prefer when game is displayed on full screen, without borders.

Another big issue, display orientation support. All S60v3 devices can either be in portrait (normal use) or landscape (think "camera") mode. On most devices the landscape mode is hidden from user during normal usage, but there are devices, like N95 or N82, which rotate the display when user physically rotates the phone. On phones that lack this feature, orientation support can be faked in software by using small drawing hacks. So consider this: phone is in portrait orientation, user runs application and sees something like that:
"Oh, display is not distorted, I can rotate the phone and play, how nice" he thinks. And most of the time he's correct. But when he has that new and shiny N95 this happens:
The phone has switched orientation to landscape, the application didn't follow. MAJOR FAIL! My SDL version correctly handles such situations:



Marcus writes on his site that his SDL allows "S60 programming without pain of Symbian!" This is completly untrue, as Marcus promotes the use of symbian-ridden CSDL class, which more or less requires some arcane knowledge. And when we're at it, just look at the documentation. There's a plethora of bells and whistles to enable or disable, only you don't have the slightest idea which option does what and some of them are there just because they can be. Take virtual mouse cursor for example. I doubt it was used anywhere (not in C2Doom for sure) and my experiences with OpenTTD, which is a mouse-driven game, has proven that it's completly unusable.

The amount of such undocumented or useless features only makes the code harder to read (oh, you don't want to look at it; 5 different coding styles in just 20 lines of code), without giving any profits, so the most sane option for me was brutal removal. So long, virtual mouse cursor, bye, various display modes, adiós console view, пока display overlays. You won't be missed. Such Reduction Of Useless Features not only makes the code easier to read, but also reduces the number of potential bugs and makes adding new (but this time usable) features less daunting task.

Of course, the library is still not finished (will it be ever?). Despite the fixes mentioned above and all the smaller ones, like fixing palette animation, making sound play smoother, there's still a lot of work to be done before I will be able to just get some random game using SDL and compile it for my phone without much ado. But even with having that said, my SDL port is The Best* symbian SDL version currently available.

* for me.

9 comments:

oApChSRp3sBenBhxmUhi0jXjyyJ0tWSA said...

Hello there!

Is there a way to get hands on your version of SDL? I am going to desperate on the version of Markus.

oApChSRp3sBenBhxmUhi0jXjyyJ0tWSA said...

I just realized you have a git repository. Thanks in advance!

wolf said...

In case someone doesn't know how to handle git, he can get the latest snaphot using the following link:
http://repo.or.cz/w/SDL.s60v3.git?a=snapshot;sf=tgz

oApChSRp3sBenBhxmUhi0jXjyyJ0tWSA said...

Is there a place where I can find the sources of OpenTTD? I have seen the patches but what to do with them? Patch against what?

wolf said...

Try git://git.openttd.org/openttd/trunk.git

Sami Vuori said...

I've managed to build your SDL version but it seems to have something odd going on:
I built the library (sdl.lib) after modifying the sdl.mmp file a bit (SYSTEMINCLUDE include and SYSTEMINCLUDE ..\include into USERINCLUDE include and USERINCLUDE ..\include), and it went OK with no errors.

Now when I'm trying to compile my own app (http://friedspace.com/SDLTest.c), my project gives an error saying:
"Undefined symbol: '_main'"
and after that
"mwldsym2.exe: referenced from 'int E32Main(void) (?E32Main@@YAHXZ)' in ECRT0.CPP:36 (ecrt0.lib)"

I have included every single library file there is in my \epoc32\release\winscw\udeb path but it doesn't help.

I'm trying to compile it onto S60v3 FP1 with Carbide.c++ v2.0. Maybe you could try to build it if you'd have any luck?

This project compiles onto Anotherguest's ESDL with no problems and it runs OK on the emulator. I'm still very interested in your SDL version because it seems to have the mightiest specs out there.

wolf said...

You may need to install Open C plugin for the SDK. I do not support, nor plan to support the emulator as it's too much trouble for no gain (it has nothing common with the real device).

I have managed to compile your code with few simple changes. The sisx + build files can be downloaded from http://team.pld-linux.org/~wolf/SDLTest.7z

Few hints:
1. Don't use HWSURFACE. It won't work. From what I vaguely remember, it's not that good to use even on PC.
2. You must currently use resolution that matches phone's. Both orientations work. Support for less-than-phone resolutions is on my TODO list.

slouken said...

I just had someone ask about a Symbian port of SDL 1.3. Is that something you're at all interested in working on?

wolf said...

I don't have such plans.