Game Design, Programming and running a one-man games business…

Category: programming

Venturing further into online bits

Today I didn’t write a single line of  C++, but did code a lot of php, which is the language I use for the online challenge management stuff in Gratuitous Space Battles.

On thursday I spent a lot of time blasting out the music from Star Trek : First Contact while I scrubbed out my chalk board and drew my vast plans for the future of GSB, or at least, the next DLC/expansion thing. After a lot of hand waving, I’m currently planning on a cunning meta-game style campaign that slots into some of the existing challenge data. It’s going to work a bit like spore, in that it becomes ‘massively singleplayer’, with other peoples content (in this case fleets) appearing in your game.

So far, so easy. That’s not a problem. The tricky bit turns out to be that although I let people mod the game (and that will continue), I can’t have a modded fleet turn up in someone elses game, because at worst, it could crash thinking “cannot find ‘bobsZapGun’ module…”

The solution, (which doesnt check for data changes as such, but does check for simple additions), is to write code which verifies that a players fleet only uses content that exists in the main game. To do that, php code was needed to crack open the binary challenge data and go through each ship hull and module name and check they really exist…

and to get THAT to work, I needed php code that would analyse all the data in the game and create a database of all the ‘valid’ entries, so that it can compare one with the other. That way if I do some module changes or new add-ons, I can just run some php and have the ‘valid data’ table automatically updated.

This is a lot of work in order to just get something totally under the hood and invisible working, which is code to ensure no modded content ends up in any one elses campaign, causing a crash. There is a ton of other work required. The good news is that a lot of this same code might be possibly leveraged at a later date to scan the high scores for modded content (and reject it) and could even remove the need to tag challenges with the add on packs manually as players do now. All fun and games….

In other news I just did a BLIND taste challenge and I *can* tell the difference between cadburys and morrisons chocolate buttons. (Cadburys taste smoother).

Spot The New Feature

It’s very minor. But what have I changed in this screenshot below?

I’m supposed to be finalizing the new expansion. I’ll do more work on that tomorrow, but I’ve resigned myself to one more patch before I release it. I needed more weapon variety for them, and that meant code changes to the main game. Then I suddenly got a bit manic and obsessed about improving the graphics in all ways. Hence, 2 days were wasted trying to add shadows (I tried various methods but none of them look right, not without re-rendering every existing ship and a major re-write) and then a decent bloom effect. In the end, I junked all that code, because it didn’t get me anywhere.  I’ve made 3 tiny changes today to some stuff which make the game look very slightly better. Overall, it all adds up methinks….

Two new features for GSB

I was honestly trying to work on new DLC, but hey, I ended up adding and improving some stuff. One thing I ended up doing was mouse cursor changes, so it actually changes to the windows pointy finger thing now to show you that you can click something, which is quite nifty. I also added two features.

The first feature is the ‘fleet overlay’ at the left of the screen. It’s a scrollable column of icons for every ship in the fleet. The tooltips show your current damage percentage, and they fill red as the ships take damage. you can also click them to zoom to that ship. It’s a handy way to see at a glance in big battles which ships are taking hits. I also added a tiny arrow icon to toggle that new feature on or off, in case some people don’t like it. I have a tiny UV bleeding issue on that button I must fix…

gratuitous space battles fleet overlay UI

The second feature is rather cool for statistics-freaks. If you have played much GSB, and spent much time on the ship design screen, you will know the frustration of seeing “weight=122” and not really knowing how that compares to anything else. Obviously you can go through each module of the same ship class and compare, but wouldn’t it be better if the game makes that trivial to do?
Tada! It does. You can click any of those data entries at the bottom left now, and get a comparison window, ready sorted and scrolled to show where the current module fits in. I hope people find this useful.

gratuitous space battles ship design screen

Now I can get back to work designing fleets for the religious aliens in the next DLC…

Both these spangly new things will be in version 1.32, which will get released shortly before the new DLC. Yay!

Programming Gratuitous Rocket Trails

I was watching District 9 ( I liked it, except the more yucky violent bits), and there were some cool rapid rocket trail effects in it, and it suddenly reminded me that the rocket trails in Gratuitous Space Battles aren’t good enough at high speed. Take a look at this rocket trial, from a rocket cruiser missile at 4x speed:

Crap isn’t it :D. At normal speed it’s fine, but at super high speed, the missile actually moves too fast per frame of rendering for me to actually space out the particles. So I just knocked up some code that instead of doing this: (pseudocode)

HowFarHaveWeTravelled?
IsItTimeForAnotherParticle?
IfSoPlaceAParticleHere

does this:

for(distance_accounted_for = 0; distance_accounted_for < actual distance, distance += particle spacing)
{
  Position = LastMissilePosition
  Position += (distance_accounted for)
  Place a particle at Position;
}

Which is more work :D But it’s worth it, because even at 4x speed it now looks like this:

I know it’s a bit late to be worrying about all this months after the game came out and got reviews, but I am just completely drawn towards tweaking the game to look better. Also this means I can experiment with superfast rocket trails which will still look good. Also today I’ve done all of the debris and turret gfx for the new race in the new DLC/expansion pack thing. Now I have to actually design their ship configurations, and allocate their bonuses. Then I need to do their mission deployments, and then it’s pretty much done (and I then need to balance and playtest it). Yay!

Vertex Buffer Driver Hell

Some days as a programemr suck. Today is one such day.
All my old games use directx7, with my own engine,. Gratuitous Space Battles uses a new engine, directx9, and all is well.

In January this year, Kudos and Democracy stopped working for lots of people with the new nvidia drivers. They got crashes in the vertex buffer lock code. Obviously I hadn’t changed a thing. the games had worked fine on thousands of PC’s for years. Suddenly nvidia must have changed the way they handle vertex buffers under directx7. Thanks guys!

The old code was very old school and simple. I locked a vertex buffer, then copied in memory, then unlocked, and rendered from them. Big deal. I didn’t use any cleverness with the buffers gradually filling up and then discarding them. (I do that in GSB) I always locked the whole buffer and the lock flags always looked like this:

HRESULT hr = VertexBuffer->Lock(DDLOCK_WRITEONLY | DDLOCK_DISCARDCONTENTS | DDLOCK_SURFACEMEMORYPTR,
(VOID**)&BufferMem,&bufsize);

For every VB lock. I did a few of these each frame, mainly for rendering text. This may not be optimum, but it worked fine, all return codes checked ok on all cards and all drivers.

Suddenly, on my nvidia 8800 GTS, and for everyone else with new drivers (except the 9800 GT), this crashed, and would only work if changed to this:

HRESULT hr = VertexBuffer->Lock(DDLOCK_WAIT | DDLOCK_SURFACEMEMORYPTR,
(VOID**)&BufferMem,&bufsize);

In theory this is less efficient. But suddenly it works. Hurrah. Except not for 9088GT owners. I tried this:

HRESULT hr = VertexBuffer->Lock(DDLOCK_WAIT | DDLOCK_WRITEONLY | DDLOCK_SURFACEMEMORYPTR,
(VOID**)&BufferMem,&bufsize);

This also works on my 8800GTS, but even this does not work on the 9800GT. I can’t get a reply from nvidia, and the developer forums there hurl abuse and sarcasm at anyone who dares to ask about why a directx7 program won’t run (I’ve read a fair few threads there). Apparently we should all just STFU and re-code everything in DX10. Err right….
Anyway, I have nothing to say on this topic other than it depresses me. I don’t want to be fixing games I finished a few years ago, I want to work on new stuff…but obviously I need to support all my customers. I just wish someone at nvidia would tell me what they changed, and how to work around it for all their video cards. I emailed them a few days ago but got no reply…

If you work an nvidia, or know everything about directx7 VB usage with modern drivers, please shower me with your wisdom. And if you have an nvidia card, feel free to try the demo to Kudos 2 or Democracy 2. Both should now work, but I’d love to know if they don’t, what video card and driver you have…

bah :(