BulletML plugin, preview release

First release! Give input!

Download plugin 1.01 (preview) .zip updated link 19.07.

Download example (exe & .cap), you can modify the xml files to

change the patterns.

Source code

<img src="http://paahdin.com/projects/bulletml/images/select.png">

Shot from example app - aircraft sprites by Mark Simpson

* What is BulletML?

Bullet Markup Language is an XML-based system for describing bullet

barrages in shoot 'em up games. It is designed by the prolific

shooting game author Kenta Cho.

The BulletML page with the manual can be found at

http://www.asahi-net.or.jp/~cs8k-cyu/bu ... dex_e.html.

Here's an example:

<?xml version="1.0" ?>
<!DOCTYPE bulletml SYSTEM "http://www.asahi-net.or.jp/~cs8k-cyu/bulletml/bulletml.dtd">
<bulletml xmlns="http://www.asahi-net.or.jp/~cs8k-cyu/bulletml">
    <action label="top">
        <fire>
            <bullet>
                <direction type="absolute">90</direction>
            </bullet>
        </fire>
    </action>
</bulletml>[/code:313wpgtq]
This script fires one bullet at angle 90, default speed. Not terribly 
useful yet. Here's a more complex example:

[code:313wpgtq]<?xml version="1.0" ?>
<!DOCTYPE bulletml SYSTEM "http://www.asahi-net.or.jp/~cs8k-cyu/bulletml/bulletml.dtd">
<bulletml xmlns="http://www.asahi-net.or.jp/~cs8k-cyu/bulletml">
    <action label="top">
        <fire>
            <direction type="aim">0</direction>
            <speed>150</speed>
            <bulletRef label="seed" />
        </fire>
    </action>

    <bullet label="seed">
        <action>
            <repeat>
                <times>100</times>
                <action>
                    <fire>
                        <direction type="absolute">$rand * 360</direction>
                        <speed>200 + $rank * 200</speed>
                        <bullet />
                    </fire>
                </action>
                <wait>50</wait>
            </repeat>
        </action>
    </bullet>
</bulletml>[/code:313wpgtq]
This script fires a slow-moving bullet, aimed at the player, that in turn spawns 100 other 
bullets at 50ms intervals, in random directions. The speed of these 
bullets depends on the difficulty level (rank).

[b]* About this plugin[/b]

This plugins adds a BulletML object that can read and play BulletML 
files. It is a bit like the existing particle system object; you can 
have multiple emitters and each object renders its own bullets. On the other hand, individual bullets are not individual Construct objects.

While any bullet pattern could be created with events, describing them 
with external files is more reusable and they can be modified without 
changing the .cap.

[b]* Appearance[/b]

You can change the bullet texture and size. Standard colour filter, 
opacity and effects are also available. Bullets can be oriented to the direction they are travelling.

[b]* Collisions[/b]

This object has its own collision condition. All collisions are bullet 
point against object bounding box. Arcade shoot 'em up games usually 
use hidden hitboxes that are smaller than the player craft.

Bullets are destroyed when they collide with an object.

[b]* Lifetime[/b]

Bullets are destroyed when they collide, exit the screen (toggleable) 
or a number of milliseconds is exceeded (configurable).

[b]* Units[/b]

Speeds are pixels per second, time units are milliseconds. The BML spec 
treats time values as frames for some reason but this wouldn't be very 
useful when frame rate can be anything from tens to hundreds.

Separate multiplier values are provided for speeds and time values.

[b]* Directions, targeting[/b]

(absolute directions) When script type is "vertical" 0 is right and 90 
down. With "horizontal" 0 is up and 90 right.

If you want the bullets to fly in the direction the emitter is 
pointing, use "relative" direction and angle 0.

When no direction is specified, "aim" is assumed; bullet flies to the 
x,y coordinate set by "Set target position" action.

[b]* Error reporting[/b]

This object has a "On error occurred" condition and "Last error 
string" expression. Useful for spotting XML errors.

[b]* Limitations, known issues[/b]
[ul]
	[li]BulletML does not define a bullet's appearance. Maybe it could be[/li]
[/ul]added (but it would break compatibility).
[ul]
	[li]If you destroy a BulletML object all its bullets are destroyed as[/li]
[/ul]well. You might want to wait until the bullet count is zero. I can 
probably add a smarter Destroy action.
[ul]
	[li]changing the filter color affects the currently existing bullets as[/li]
[/ul]well. While consistent with Construct, it might be more useful to have 
a separate color property and Set Color action.
[ul]
	[li]bug: if a script contains "vanish" action, Finished condition does[/li]
[/ul]not always trigger.

Any benchmarks for speed/ # of objects yet?

Also I'm kind of curious (before I download and test) as to what your using for bullets, sprite etc.

It doesn't use Construct Sprites but handles its own rendering (technically: textured quads in the case of rotated bullets, point sprites when there's no rotation).

Haven't ran very scientific benchmarks, but it's pretty fast. Here's a test I did just now:

Over 20000 bullets on screen (a bit of a challenge for the player ), colliding with one object (player ship), still pushing over 60 FPS. (2.8ghz dual core, GF 9800 GT).

<img src="http://paahdin.com/projects/bulletml/images/lotsa.jpg">

stare at this long enough and your screen will begin to wave

I can probably optimize it further, but there's still features to be added first. Anyway, performance is not the main catch here (Construct could easily push a few thousand Sprites -- more than enough for games) but the ability to script the patterns.

Thats pretty cool Luomu. Great screenshot too.

An editor would be nice where you could change parameters and see the bullets patterns in realtime and then export the xml file.

hey luomu

might I suggest posting this in Construct Discussion?

it's become the unspoken standard place to release new plugins, or plugin betas, and alot more people will see it. I think the average user ignores the Construct Engineering board, because it's mainly for plugin developers and construct developers to talk about the development side of things

Very interesting. I like the concept, and it has its own advantages and disadvantages compared to doing it with events. I'm liking the cleaner event sheet and increased performance for massive screen filling patterns. However, with events and sprite based bullets you still have more control. Useful addition nonetheless. Another great plugin Luomu!

(back from the greek sun)

I will post this somewhere more visible when it's less rough around the edges. Things I still need to do:

• Fix bugs!
• Create a cool demo game (just one level)
• Look again into using Construct objects as bullets, earlier I deemed it too tricky

Notable things I've added lately:

* Ability to use construct objects as bullets, allows for example per-bullet effects like trails and using the existing collision detection

* Easy "play file name.xml x times with delay y milliseconds" action

<img src="http://paahdin.com/projects/bulletml/images/mutants.png">

Little green mutants with trails

Notable things I've added lately:

* Ability to use construct objects as bullets, allows for example per-bullet effects like trails and using the existing collision detection

* Easy "play file name.xml x times with delay y milliseconds" action

<img src="http://paahdin.com/projects/bulletml/images/mutants.png">

Little green mutants with trails

So, uh, are you going to release that one? I really couldn't use this unless it supports per-pixel collisions.

Other than that, I really like the idea of being able to create patterns this way. Soooo much more organized than my current method.

So, uh, are you going to release that one? I really couldn't use this unless it supports per-pixel collisions.

Oh yeah, have a look: BulletML-1.01.zip. Still not an official release though.

For this week I'm on a machine with no dev tools so I can't quickly fix any bugs. Been working on the demo game instead.

Ah I see. Well epic stuff, Imma give this a go.

Im actually in a point in my danmaku engine where, if I can make interesting patterns with BML, I can probably contribute a demo or two as well.

At last released the first official version of the plugin in here and the demo game here. It was a bumpy journey.

Wow good stuff. I will probably never make a "bullet hell" game, but this could be useful for many other things too.

Nice work mate.

~Sol