We Have Established Control and a Programmer Speaks Too Much

We Have Established Control

Progress is continuing!  This update includes some new features, a video about the new escape menu, programmer talk, and a little mood music.

Pick it up Man! and A Little More Control Please

Pick it up Man!

More changes for the Amulets & Armor project.  This update I’ve got an interesting video for you.  It shows how you can pick up items now in the look mode.

WASD with Mouse and Spawn of Lysle

WASD with Mouse

Since my last post, I’ve been working on making the keys work using the WASD keys and the mouse.  I wasn’t too sure how this would work out, and honestly, I’ve never done these types of controls in a game, much less in a windowed game.  Other than a bout of rea life interruption, the new code was not terribly hard to add.  The video attached shows more…

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Removing the Curse

 

 

Removing the Curse —  One Bad Bug

I cannot help but be pleased by my work today.  Although I did not get the new WASD and mouse controls fully working yet, I got side tracked with a bug in the system.  Working with the game lately has been a bit of trial and error lately because each time I ran the debug version, I would get an error about every 2 minutes or even sooner when I started casting a large number of spells.

Irritated by the instability of the system, I changed my tactics from adding or changing the code to finding that bug NOW.  The little voice in my head was already screaming at me that I was being unprofessional and letting my desire for new shiny features distract me from the mundane and obvious problem before me — that the product was being taken down by a small infestation of memory mangling termites.

Using a magical routine called _CrtCheckMemory() along with my own house rolled MemCheck() commands, I was quickly able to setup a system that searched high and low for the tale tale signs of an unwanted visitor.  Nevermind that the frame rate dropped to less than 1 (a screen update every 5-10 seconds), but I was able to setup a test that would cause the bug to show itself.  And low and behold, it was in the effects system.

The effects system tracks what effects are on the player.  Cast regeneration, and you get a small icon on the side of the screen and your character regenerates.  But the effects were not working correctly.  Come to find out that the small memory structure allocated for the effect was the WRONG structure.  And I when I mean the wrong structure, I mean the wrong structure.  Somehow the inventory structure was being used in place of an effect structure (ahh, the one flaw of C — too much power).  The proper structure is bigger than the one that was being allocated and writes to the effect were scribbling past the end of allocated memory, thus, corrupting the heap.  Since most spells create an effect of some type, this explains why I thought the spells were cursed!  They were slowly destroying the memory space.

Now I’m able to play the game again and for long periods of time.  Alright, I admit it, I played for about an hour today without a crash.  It was nice never seeing a bug … until … I tried to quit and found a new bug.  Sigh.  The good news is I was able to use the tools developed above to identify what caused the crash, I just have to figure out how to easily recreate it.  (It occurs when a blood splatter disappears off the ground at the same moment you complete a level — how’s that for a rare bug!)

My general rule is to find a test case to recreate the bug, verify the bug exists multiple times, fix the bug, and then test that the bug is gone.  I hate bugs!

Return of the Avengers and A Little Music Please

Return of the Avenger

I did a little bit of testing across the different levels and went back to Quest 4: Exiguus and the Undead (sounds like a band name, doesn’t it?).  Running around the level, all was going good until I died.  Well, I died but I could see no attacker.  Holy Toledo, Batman!  I introduced a bug that allowed monsters to attack through walls, right?  Or maybe some weird problem with the creatures in the floors attacking me, right?  No.  I just had forgotten to add back in one of the many routines to draw colorized creatures onto the view.  In effect, our old orange knight (known as the Avenger, who has been nicely colorized from the standard gray knight into that wonderful Halloween orange) was just not being drawn.  And, since I was using a 1st level character, he trounced me in 3 or 4 hits without me seeing whodunit.  Not to worry, about 3 lines of C code later and the Avengers are back in action.

A Little Music Please

As I stated in my last post, I’ve been working on the background music.  What a surprise this turned into as I had to work the music code differently than the original DOS game.  In the old HMI Sound System, I used routines to stream the music in block by block letting the HMI system tell me when to pull in more.  This was done for memory reasons as we were targetting 4 Meg/8 Meg computers and the sound tracks were about 6 Megs on average.  Flash forward years and I have decided to just load the whole track  instead of the piecemeal system.  Load times are not even an issue.  Unfortunately, I found myself introducing a few dozen bugs.  When the sound is turned off, crash.  When the sound is set to the lowest volume, crash.  When you enter a new level, crash.  When you exit a level, crash.  Yeah, embarrassing how this bug was owning me considering I had just wrote a sound mixer in an evening and yet this bug is messing with me over and over.

I’m glad to say, I’ve dealt with the problem (take that nasty bug!) and background music is working just fine …. ::prepares to slap computer::

Now music is working just like the full system.  You have full control on how loud or soft the music is in the options dialog.  And while I was at it, I fixed some other issues with changing the sound effects level (they would pop when you changed their volume).  I think we are done there.

Next up WASD Controls!  In the old DOS game system, you would go into SETUP.EXE to configure all your custom key strokes.  I’m going to look into putting this configuration directly in the game.  I wonder if I can make that work for both DOS and Windows.  Hmmm … seems simple enough, right?  Might give me a good reason to put a menu in there instead of the “Press ESC again to exit the level…”  I’m also going to look into creating a Look key that switches between the mouse being active with look/pick item actions or making the mouse control the facing of the player.  Yes, this means there needs to be a turn speed and fun stuff of that nature.

This will probably be a big change.  But it should bring that feel that players have with current controls into the game.  Oh, and if someone doesn’t like the new keyboard layout, it’ll be easy to switch back.

Hold on, am I going to have to do some artwork in Deluxe Paint again?

In Like Flynn and Bad Spells are Cursed

In Like Flynn

And just like that, sound is now back in the game.  I’m pretty pleased with the results.  Even though I was wrong about the SDL_mixer library not having a pan/stereo feature (it did, thanks for pointing that out NotPyry), I went ahead and created my own audio mixer.  Come to find out, they’re really not that hard to put together and I get the ability to customize it to the game a little bit (volume controls, mixing settings, etc.).

The system now can play 32 simultaneous sounds at 16-bit 44 kHz.  Measuring performance shows that on a simple test scene where we get 880 fps, the sound system drops it down to about 800 fps when all 32 sounds are playing (or something close to that — I was just spamming spells as fast as I could).  Most levels will have no more than 8 sounds at once standing still and about 12 when the combat is going.

On top of it, stereo/panning is working and I was able to play the game in all its glory.  I had no problems with sound distortion or even the “crunchy” sound I’ve had in the past (which surprised me).  Maybe that’s because I do the clipping check at the very end of the mathematics and use the full spectrum of the audio system (16-bit 44 kHz instead of just 8-bit 22 kHz).

Overall, I’m very pleased.  I even got frequency bending working (this allows a 11 kHz “Ugh!” sound to be changed to a higher or lower frequency version of “Ugh!” at no extra cost).

But I’m not done.  I don’t have the background music back in there and need to clean up the code a bit so the DOS and Windows version aren’t intermixed.  I don’t expect there to be big changes in the future, but it would be nice to be able to read the code better in the future.  For the Windows version I’m going to drop the MIDI and just stick to digital looped music.  I’ve got the files and downloads are no longer 19200 baud modems.  Background music will only cost 1 more constantly on sound effect in the system.

Bad Spells are Cursed

As I’ve worked on the code I get an occasional heap corruption in the debug version that crashes the game.  I was so excited to have sound that I started playing Quest 7 Map 1, and since I forgot how to get the exit to work, I spent a considerable amount of time trying to figure out the puzzle (yeah, I should remember this, but I don’t).  Just as I was about to get the last step figured out, crash!  Sigh.

But here is the good news, I’m seeing a pattern.  There seems to be a link between casting an invalid spell (I didn’t have my list of spells handy) and this heap corruption bug.  It’s not a 100% thing, but the more invalid spells you cast, the greater the chance of a heap corruption.  There may be more bugs in the system, but this seems to be the first well hidden bug that has a pattern to it.

Stereo for the Deaf

And just like that, we have 3D working (not OpenGL) up and running.  I found the math problems were just some incorrect calculations of which pixel to use in the texture.  BTW, after looking at this code, it wouldn’t be hard to make texture rotate on the walls. … Hmmm….  I have a picture of Elymas’s lair where all the walls are blue and rotating in my head.  That would be headache inducing.  We’ll save that one for later.

But the above was the easy part.  I can walk around and run through the level, kill elves, cast spells, and just generally play the game.  But … there’s no sound.

Sound has always been a bit of weird spot for me.  You see, I’m deaf in one ear.  The technical term is Single Sided Deafness.  Through a small birth defect, I have no ear canal on the left side.  Everything else is normal, just no ear canal.  Sort of like having an ear plug all the time.  So, when I hear sound, it is (mostly) in the form of mono.  This website does a good job of explaining the side effects of having SSD — both physically and (surprisingly) psychologically.

Making A&A pushed my ability to listen to sounds in stereo and in a game world.  And I have always wondered if I went too far with the sounds (super stereo?), but I worked with the team to get it right along with constant flipping around of my head phones.  Getting this right is still a priority in the Windows port, but should just be a matter of repeating what was done before, right?  (For now, no Dobly 5.1 sound, I have a hard time even contemplating what that really sounds like)

I’ve already done some research into doing sound using SDL and it looks like you have to create your own mixer to combine all the different sounds.  Hmm … that’s fairly limited, but that’s what I get for using the Simple DirectMedia Library.  Alright, there has to be something out there for this already since I’m not the first game programmer to use the SDL.  Fast forward and I’m looking at a library called the SDL_mixer (hey, simple name!).  Looks good.  Does .mp3 and .ogg files (tuck that away for later), plays samples of all types of formats (stereo, mono, 8-bit, 16-bit, etc.).  Let’s use it … right?  No.  One of the key features A&A is its ability to make sounds appear on the left or right based on where it is on a level.  Would you believe that the SDL_mixer allows you to change the volume of any stereo/mono audio sample, but ONLY on both left and right.  I can’t pan the sound from left to right!  There doesn’t even appear to be separate volume control for left/right.  What?  Looks like I get to make my own.  Oh well, it’ll be more what I need.

So how do we make a audio mixer?  Through the years, I’ve always have asked, how do you mix 32 sounds and not make it all sound like trash as the waveforms get louder and louder with all the noise.  Mathematically, the noise will start to clip as you “spill” over edges of the digital sample range.  So, I have always figured there had to be some fancy algorithm for combining sounds without causing the playing of 8 sounds of silence and 1 sound of music to cause the music to drop to 1/8 the volume.  The answer is … no … there isn’t one … you just add.  If there is no sound, you add nothing.  If there are 2 loud sounds, they add, and you clip.  This would explain why in A&A when a ton of fireballs hit at the same time, you start getting a kind of ‘crackle’ sound in the original HMI sound drivers.  Over time, I came to like that ‘crackle’ sound effect, so we’ll do the same.  Mix by adding, clip the sound range.  Luckily, not all sounds play at 100% volume, so if you got two sounds at 50%, then they can add with no penalty.  Soft sounds are almost free (10 sounds at 10% max volume).  But when the loud action gets going, look out!  Strangely, I’ve been doing some video and sound playback at my day job lately that is similar to this.

Enough talk, more action!  Off I go to make me a sound mixer….  with stereo panning capabilities.

First Attempt at 3D – If a Bit Fuzzy

 

 

 

 

Sometimes it is nice to see progress being made in the smallest chunks.  One of the most exciting parts of working on a 3D game is seeing it improve little by little, even when what you as the programmer is minor to other people.  Those small details add up and create a fantastic whole.

Tonight I’ve been spending the evening translating old DOS assembly routines back into C and trying to get the math right for drawing floors and walls.  After translating some 70 routines, I have the final first results below:

It is probably no big surprise I didn’t get it right the first time, but this isn’t bad for the coming out the gate.  Seems we are missing objects, the textures have a mind of their own as I walk around, and things in the distance seem to pop around.  But the sky is right, the textures are in the right place, translucent textures (not shown) are working, and the light shading is working very well.  Not bad, not bad.

Frame rate is a little low (303 fps compared to the theoretical limit of over 1400), but I am running debug code with a ton of output appearing on the other screen (also not shown).  Oh, and the Windows tools are telling me I’m corrupting memory somewhere … nice.

Moving forward ….

 

 

Windows — A New Start

So, some of you may be wondering why I’m doing a Windows port of the game.  The reason is mostly selfish — I want it in Windows.  Plus, there is more to it I’ll hit list:

• I’m a Windows guy.
  These are the tools I have and the tools I enjoy using the most.  I’m not a Linux guy and I’m not a Mac guy.  But I’m trying to lay the groundwork down so the ports to these other platforms will be easier.  See DOSBox note below.
• The tools in programming in Windows are easier to use than in DOS.
  Already I have found several small memory bugs and fixed them with the debugger that allows me to keep up a screen at the same time I have debugging output.  In the old DOS days (and pretty much still with the DOSBox version), I have to depend on a fair amount of screen flipping and the DOS version doesn’t catch as many memory fault cases.  Faster builds and faster bug catching/fixing — that makes everyone happier.
• I don’t want the game to always be dependent on DOSBox.
  DOSBox is awesome!  It really is.  And there are so many ports to other platforms that I don’t even know about.  However, I want A&A to grow with new features and I don’t want to always be dependent on the older DOS version.  For example, I would like to see OpenGL be the primary 3D engine along with some changes.  Don’t despair DOSBox users, for now I’m going to keep the product dual compiling for Windows and DOS so (at least) bug fixes and small improvements are immediately implemented.
• Better graphics (but still retro?)
  I want to see the graphics getting better in the game.  And I don’t just mean a possible move to OpenGL.  I want to see higher resolutions, more frames of animation, and color depth.  I cannot do that (easily) in DOS/DOSBox.  The game will probably stay retro in view (blocky graphics), but there is no reason we cannot make the engine itself more engaging.

So where am I now?

Here’s a couple of screen shots of the current Windows version:

I’m currently scaling the 320×200 into a 640×400 area in a 640×480 window (that’s why there are big black boxes).  I’ll probably put in a scale to 640×480 soon, but I just wanted to keep it 1×1 to 2×2 for now.

Current performance numbers on optimized release code shows I’m getting about 1400 fps on the raw UI to SDL drawing code, which is more than enough for the final, but I am running on a quad-core 2.8 GHz machine.   NOTE: I have not optimized the windows drawing routine heavily yet.

Oh, before anyone gets excited about a 640×480 view of the world, no, I’m just doing a 320×200 scaled up to 640×480.  At this point, I’m still just focusing on getting the system up and keeping it fully DOS compatible.

 

Preparation of a Release

While I’m waiting on legal paper work, I’ve been doing several things in the last couple of weeks:

• I’ve pulled out the source code and tried to figure out what I’ve got and don’t have.  Surprisingly, I think I have most everything except the original sound recordings (pity, I think many were 16-bit and this will leave us with their 8 bit final versions).
• Looked for original documents and what-not for fun and found the 2nd rev of the game notes, but have not found the original hilarious versions.  (David’s 1st set of notes would have been amazing to read to others because it contained so many strange ideas)
• Setup a DOS Box configuration that works with the original tools to compile the code and to create the resource files.   It works and works quite well.
• Messed a bit with getting the debug version of DOS Box to let me see where crashes are occurring.  Without proper debug files showing me the map from assembly to C code, this is, well, annoyingly NOT useful.  It just helps me know that it crashed and a general location.  Very painfully slow to use.
• Got the old Watcom debugger working with the DOSBox build of the game and could actually use it to step through the code.  However, with DOSBox’s limited 25 line display (I can’t get 50 line DOS to work), this is also painful as I can only see about 5 lines of code most of the time.  But it works.
• Downloaded Open Watcom v1.9 and got the executable compiling from Windows tools instead of inside of DOSBox.  I did this mostly because it is much faster to compile in native code instead of emulated DOSBox code.  It works pretty good.  Oh, and did I mention the game still runs with a new compiler.
• Compiled DOSBox.  Was curious how hard that was.  It took an evening, but now if I want to customize DOSBox for this project, I can.  The more I consider options, this is becoming less necessary.
• Started porting the game over to Windows using the SDL.  The SDL appears to be the best cross-platform tool out there and I like its simplicity.  I’ll report more on this in another post.  Android support for SDL is questionable, at best.

Things I’m still looking for or need to do,

• Original Ad.  It’s around here, but I said I would post what our original PC Gamer magazine ad looked like.
• Still hoping I’ll find the original sound files on a disk somewhere.
• Got some Zip 100 disks I need to copy everything off of — before parallel ports totally disappear.  Yes, I got the parallel version of the zip drive still.  (Side note: I collect too much junk)
• Decide on how I want the networking to work — IPX or something else.