JEPE - Game Engine

[DrCoolSanta]

BonzaiRob, I am developing an engine as well, so kinda like we are competitors now, mine is based on SDL, but i realize that all your game is made in XML which is interpreted, right? Isn't it gonna be so easy to destroy a game by just editing it so easily?

I am interested so please do reply.

[Pivot]

Working on http://pokecommunity.com/showthread.php?t=105235 .

I suppose we're the 'non-engine' games. There's also POL, obviously, Ekaiyo, and PokeQuest.

EDIT: Well, as for what DrCoolSanta said, there will always be ways to cheat in single-player PC games. I'm doing a multiplayer thing, so we can handle logic at the server side. However, even if you use binary for maps, some technically proficient guy can just bring up a hex editor and go to town. This is just an engine, anyway, so you should be able to edit your own maps.

[Zofride]

yea looking sweet, anymore info?

[BonzaiRob]

DCS: yeah we're thinking about that. We'll probably have an online repository, and compare between on and offline data whens someone logs in, and flag it for a mod if there's a big difference (depending on time). Anything really unusual will just get banned from the server. Pivot is right though, there's really not much we can do.

Zofride: What would you like to know?

[Zofride]

Yeah this looks allright, keep going.

[Improfane]

This would be awesome as an applet game. You'd be able to play in a web browser, integrate it with game rankings and you're set.

My only question would be, why XML?

I would never use XML for maps, only things like NPCs and shops lists.

[BonzaiRob]

We're going to integrate with web rankings too, there'll be a new trainer rating system. There's been some starting work on an applet system but nothing major yet.

XML: because it's really easy to work with.
Here's a standard tile (typed from memory, it's easy)
<tile image="grass2.png" x="15" y="14" />
then a fill:
<area fill="grass2.png" x="15" y="14" width="20" height="10" />
Wildgrass is a bit more complicated:
<actiontile class="WildGrass" baseImage="wildgrass1.png" animComingOver="WildgrassComingOverAnim.png:4,1:250:false" imageOnOver="wildgrass1OnOver.png" imageComingUnder="wildgrass1OnUnder.png" x="13" y="20" />
(class is the type of tile, base is what's normally there, then with the rest: either animation or image; coming, on, leaving or off; over or under the player.
You can also fill actiontiles.

And then objects:
<object image="tree.png" x="9" y="-2" recty="1" rectheight="2" />
recty (and rectx) are the offset of the collision rectangle, and the hight and width are obviously the height and width. So for that tree, I've offset the rect down one and made it smaller so it doesn't stick out the bottom.
You can also group objects into sets with relative x and y, fill objects in a linear way like the tiles, or fill objects in a pattern (like offsetting a row of trees).

Maps also set the maps around them (for smooth map movement) and the offset, so maps don't all have to be the same width and height to line up. Our overworld to-do list is currently warps, actions and NPCs, layering, and objects that only work if you walk into them from a certain direction.


To be honest, we were considering something else for NPC scripting at one point.. might have been Ruby. XML is ok for that, but it'd use a lot of if clauses to read a simple plot, and it can't send out instructions (like 'move on to the next plot point').

[Improfane]

As long as you know what you're doing.
My tiledata looks more like this:

[6,,,,,,,,,,,,,,,,,,,8,,8,,,,,,,7,,,,,,,,,,,,,,,4,,,

It doesn't need to be parsed in the same way.

It's just a single dimensional array.

[BonzaiRob]

How do you allow for the player walking in front and behind things? Do you have another array specifying which tiles can be walked on and which not?

[Improfane]

Yes. I talk about it in my outdated article here.

The most up to date article can be found at the fangaming wiki.

Perhaps I'll transfer some of my data to your wiki if if it uses the general free documentation license too.

[BonzaiRob]

It does, yeah, but don't do it if it's a chore

[AJUST]

This sounds amazing, and is something i've always waited for. One thing I'd like to ask is if it's possible that you could store the graphics as image files, so they're easily customisable.

[BonzaiRob]

After a delay due to schoolwork, it's finally time for [Demos!]

JEPE should start moving again soon.

Originally Posted by AJUST

This sounds amazing, and is something i've always waited for. One thing I'd like to ask is if it's possible that you could store the graphics as image files, so they're easily customisable.

Definitely.

[The Dash]

Just an FYI dude, the program won't run until it is updated, you should upload the working version and give people details on updating via SVN.

Edit:

I like what I'm seeing man, this is all your own work? Very nice.

One bug I noticed is that when you press Shift and try to run, your Character will be stuck at running speed, I'm sure you're aware of this though.

Good work!

[BonzaiRob]

It says as much in the Readme, we know :p As for updating it, this is the updated version. So it should run... we've been getting some errors on some Windows PCs though, still working on that.


EDIT We have a new demo up! It's at http://jepe.ptreasures.net/demo.php .
Hopefully this should sort out the problems that were stopping some Windows users from running it, and yu can now warp between maps (the lab in Maplewood and Peachblossom Woods are the two examples we currently have).
Coming next will probably action objects, such as houses, and more actiontiles (signposts, footprints, water). Not to mention a battle engine, which is doing strange things atm.

[Zerro]

Im here to offer my support in anyway I can. Just let me know how I can help.

[FMY]

Ok, as the second founding member and lead programmer of JEPE, I decided to answer some questions too.

Er.. couldn't you just release a JAR file for other platforms? Java doesn't need to be recompiled. I'm also wondering what you'll use to distribute. We're using Java Web Start for now.

I don't really know why Bonzai's saying we've got compiling problems, I can't recall having them once. I did compile one demo for java 1.6 once, instead of 1.5, but that's about the biggest compiling problem I've ever got. We haven't made any jars for now, but simple bash scripts to start the game. In the future, executables for windows and jars for other platforms will be available, though I don't know if we'll be using Java Web Start since linux's got problems with that.

Also, you should be able to implement a resizable game (and I don't mean doubling up your pixels) if you're using Swing/AWT. Just make your interface elements reposition when the window resizes. I'm not sure how you're implementing scrolling maps, so I can't comment on it. We have offsets that are added to the map X and Y; they're added and subtracted along with the player position.

True, but we don't want that to happen. Currently you can specify the window width & height when starting the game however,

We're using the Tiled mapping format, which is XML-wrapped, but uses Base64 for tile data. Nice and space-efficient. It also has an existing map editor, which is a definite plus, as well as the ability to export back into pure XML if needed.

Now this is something interesting. I wish I'd heard of this before. I'd like to use this format too, but I don't think it's worth the effort. After all, there's still a lot missing in the editor, using this format would mean a big rewrite of the engine and some change to the format to add things like our actionTiles.

As for why we're using XML: listen to Bonzai. The first version used 2-dimensional arrays, but that's not something you can write by hand easily, so I thought XML would be better.

@Zerro: great! Thanks man. The best way to help us is to help us with writing the engine, or to submit ideas for file formats to manage the pokémon data, item data, move data and ability data. I'm currently working on finishing the mapping language now, so other people can start mapping, write editors and help me with the parser. If you'd like to write the specs for another file format, it would be nice to do it in a similar way. Unfinished documents can be found here: h ttp://jepe.ptreasures.net/documents/ (remove the space)

[Callydude™]

Grave Digger!!What is it with newbs and not reading the rules.Don't revie old threads.it is really annoying.

[Yuoaman]

Well in all fairness I don't really consider what he did gravedigging... He's a founder of the project answering some questions...

[FMY]

I checked the last post's date and didn't think Januari 8th was very old, so I thought it was be OK to reply to the thread. I'm really sorry if I did something wrong.

[BonzaiRob]

I thought I'd just mention a few little updates that will be available soon:


Battle: Currently migrating from a static test to dynamic variables, so that instead of always playing as Sputteren against Maudi, you choose a starter and fights are triggered on the overworld.

Cutscenes: It will be possible to program cutscenes, game intros and similar movies all in XML. The next dmo will have a small intro.

Flickers: The game tended to flicker on slower processors, but that's been rectified now, and the game runs much smoother.

There will most likely be some other stuff before the next demo, depending on programming time; NPCs, actionObjects(houses, signs), and water are next on the list.

[Wichu]

Change the text colour in the data boxes to black.
And what did you do to Rattata? T_T

[BonzaiRob]

Thought I'd replied to this :/ Oh well.
The text will be changed as I migrate it to dynamic variables. Getting it coded was more important :) It'l also get put in the right place >.>
And that's not Rattata (the text is based on a text-only predecessor to this). It's Maudi, which has slightly lower attack but higher speed.