FsBulletML2.Parser 1.0.1

FsBulletML2

A BulletML engine written in F#. It runs danmaku (bullet-hell) patterns frame by frame and leaves drawing, collision and object pooling to your game framework: MonoGame, Unity, Godot or anything that can call .NET.

Core, Front and Dsl target net10.0 and netstandard2.1 (Unity). Parser and TypeProviders target net10.0.

Run a pattern

F#

open FsBulletML2
open FsBulletML2.Domain

let xml = """<bulletml xmlns="http://www.asahi-net.or.jp/~cs8k-cyu/bulletml">
  <action label="top">
    <fire><direction type="absolute">0</direction><speed>2</speed><bullet/></fire>
    <wait>1</wait>
    <vanish/>
  </action>
</bulletml>"""

let rand () = 0.5f
let rank = 0.5f

// Load once per pattern
let script = Runner.load rand rank (readXmlString xml)
let mutable run = Runner.newRoot BulletType.Enemy script
let mutable pos = { X = 0.0f; Y = 0.0f }

// Step once per frame
for _ in 1..3 do
    let env =
        { Rand = rand
          Rank = rank
          Aim = { ToPlayer = 0.0f; ToEnemy = 0.0f }
          Spawn = { ToPlayer = 0.0f; ToEnemy = 0.0f } }

    let frame = Runner.stepWith env run { run.Motion with Pos = pos }
    pos <- { X = pos.X + frame.Delta.X; Y = pos.Y + frame.Delta.Y }
    run <- frame.Run
    // frame.Spawned: bullets fired this frame. frame.Vanished: this bullet is gone

C#

The F# API is reachable from C#. Functions compile to PascalCase (Runner.Load, NewRoot, StepWith), and the readers live in BulletmlModule.

using FsBulletML2;
using Microsoft.FSharp.Core;
using static FsBulletML2.Domain;

var xml = """
<bulletml xmlns="http://www.asahi-net.or.jp/~cs8k-cyu/bulletml">
  <action label="top">
    <fire><direction type="absolute">0</direction><speed>2</speed><bullet/></fire>
    <wait>1</wait>
    <vanish/>
  </action>
</bulletml>
""";

var rand = FuncConvert.FromFunc(() => 0.5f);
var rank = 0.5f;

// Load once per pattern
var script = Runner.Load(rand, rank, BulletmlModule.readXmlString(xml));
var run = Runner.NewRoot(DTD.BulletType.Enemy, script);
var pos = new Vec2(0f, 0f);

// Step once per frame
for (var i = 0; i < 3; i++)
{
    var env = new Env(rand, rank, new Aim(0f, 0f), new SpawnAim(0f, 0f));
    var m = run.Motion;
    var frame = Runner.StepWith(env, run, new Motion(pos, m.Speed, m.Dir, m.Accel));
    pos = new Vec2(pos.X + frame.Delta.X, pos.Y + frame.Delta.Y);
    run = frame.Run;
    // frame.Spawned: bullets fired this frame. frame.Vanished: this bullet is gone
}

Links

• Source, samples and issues: https://github.com/zecl/FsBulletML-2
• BulletML specification (ABA Games): http://www.asahi-net.or.jp/~cs8k-cyu/bulletml/

MIT License.