API Reference

January 28, 2026 · View on GitHub

Complete reference for all public types in the BulletMLLib namespace.

Classes

Bullet

public abstract class Bullet : IBullet

Base class for all bullets. Inherit from this class and override the abstract members to create your game's bullet type.

Constructor:

protected Bullet(IBulletManager myBulletManager)

Parameter	Description
`myBulletManager`	The bullet manager that owns this bullet. Must not be null.

Abstract Members (must override):

Member	Type	Description
`X`	`float`	Horizontal position in pixels from upper-left.
`Y`	`float`	Vertical position in pixels from upper-left.
`PostUpdate()`	`void`	Called after `Update()`. Use for bounds checking, collision, rendering.

Properties:

Property	Type	Default	Description
`Speed`	`float` (virtual)	`0`	Bullet speed in pixels/frame.
`Direction`	`float` (virtual)	`0`	Direction in radians. Automatically wrapped via `MathHelper.WrapAngle`.
`Acceleration`	`Vector2`	`Zero`	Acceleration vector in pixels/frame^2. Set by `<accel>` nodes.
`TimeSpeed`	`float`	`1.0`	Time multiplier. Values < 1 slow down, > 1 speed up.
`Scale`	`float`	`1.0`	Pattern size multiplier.
`InitialVelocity`	`Vector2`	`Zero`	Velocity inherited from the firing entity. Applied during `InitNode`.
`Tasks`	`List<BulletMLTask>`	`[]`	Runtime tasks defining this bullet's behavior.
`MyNode`	`BulletMLNode`	`null`	The node tree describing this bullet.
`MyBulletManager`	`IBulletManager`	--	The manager that owns this bullet.
`Label`	`string`	--	Convenience property returning `MyNode.Label`.

Methods:

Method	Returns	Description
`InitTopNode(BulletMLNode rootNode)`	`void`	Initialize from a root node. Finds nodes labeled `"top"` or `"top1"` through `"top9"`.
`InitNode(BulletMLNode subNode)`	`void`	Initialize from a specific sub-node. Clears existing tasks and builds new task tree.
`Update()`	`void` (virtual)	Execute one frame: runs all tasks, then updates position from velocity and acceleration.
`UpdateAsync()`	`Task`	Runs `Update()` on a background thread.
`GetAimDir()`	`float` (virtual)	Returns the angle (radians) from this bullet to the player position.
`TasksFinished()`	`bool`	Returns `true` when all tasks have completed execution.
`FindTaskByLabel(string label)`	`BulletMLTask`	Recursively searches tasks for a matching label.
`FindTaskByLabelAndName(string label, NodeName name)`	`BulletMLTask`	Searches tasks matching both label and node name.

Position Update Formula:

Each frame, the bullet's position is updated as:

velocity = (Acceleration + Direction.ToVector2() * Speed * TimeSpeed) * Scale
X += velocity.X
Y += velocity.Y

BulletPattern

public class BulletPattern

Container for a parsed BulletML document. Parse once, use many times to initialize bullets.

Constructor:

public BulletPattern(IBulletManager manager)

Properties:

Property	Type	Description
`RootNode`	`BulletMLNode`	Root of the parsed node tree. Pass to `Bullet.InitTopNode()`.
`Filename`	`string`	Path of the loaded XML file. Set by `ParseXML()`.
`Orientation`	`PatternType`	Pattern type read from the `<bulletml type="...">` attribute.

Methods:

Method	Description
`ParseXML(string xmlFileName, ContentManager content = null)`	Parse a BulletML XML file. If `content` is provided, loads via MonoGame Content Pipeline (path should be relative, no extension). Otherwise loads from file system.

BulletMLNode

public class BulletMLNode

Represents a single element in the parsed BulletML document tree. Nodes are shared across bullets; tasks are created per-bullet at runtime.

Properties:

Property	Type	Description
`Name`	`NodeName`	The type of this node (bullet, action, fire, etc.).
`NodeType`	`NodeType`	Modifier type (none, aim, absolute, relative, sequence).
`Label`	`string`	The label attribute from the XML element.
`ChildNodes`	`List<BulletMLNode>`	Child nodes in the tree.

Methods:

Method	Description
`FindLabelNode(string label, NodeName name)`	Find a descendant node with matching label and name.
`FindParentNode(NodeName name)`	Walk up the tree to find an ancestor of the given type.
`GetChild(NodeName name)`	Find the first direct child with the given name.

BulletMLTask

public class BulletMLTask

Runtime execution unit created from a BulletMLNode. Each bullet gets its own task tree.

Properties:

Property	Type	Description
`Node`	`BulletMLNode`	The node this task was created from.
`Owner`	`BulletMLTask`	Parent task in the execution tree.
`ChildTasks`	`List<BulletMLTask>`	Child tasks to execute.
`TaskFinished`	`bool`	Whether this task (and all children) have completed.
`ParamList`	`List<float>`	Parameter values for referenced nodes (accessible as `$1`, `$2`, etc.).

FireData

public class FireData

Template data for creating new bullets during pattern execution.

Fields:

Field	Type	Description
`srcSpeed`	`float`	Initial speed for fired bullets.
`srcDir`	`float`	Initial direction for fired bullets.
`speedInit`	`bool`	Whether speed has been explicitly set.

Interfaces

IBullet

public interface IBullet

Interface for bullet-like objects. Implement this if you want to wrap a Bullet in another object.

Member	Type	Description
`X`	`float`	Horizontal position (pixels from upper-left).
`Y`	`float`	Vertical position (pixels from upper-left).
`Speed`	`float`	Speed in pixels/frame.
`Direction`	`float`	Direction in radians.
`Tasks`	`List<BulletMLTask>`	Runtime task list.
`InitTopNode(BulletMLNode)`	`void`	Initialize from a root node.
`InitNode(BulletMLNode)`	`void`	Initialize from a sub-node.

IBulletManager

public interface IBulletManager

Interface your game implements to manage bullet lifecycle and provide game state to the library.

Member	Type	Description
`Rand`	`Random`	Random number generator for `$rand` in expressions.
`GameDifficulty`	`FunctionDelegate`	Returns difficulty value (typically 0.0-1.0) for `$rank` in expressions.
`CallbackFunctions`	`Dictionary<string, FunctionDelegate>`	Custom functions accessible as `$name` in BulletML expressions.
`PlayerPosition(IBullet)`	`Vector2`	Returns the target position for `aim`-type directions.
`CreateBullet()`	`IBullet`	Factory for regular (visible) bullets. Called by `<fire>` nodes.
`CreateTopBullet()`	`IBullet`	Factory for top-level controller bullets (usually invisible).
`RemoveBullet(IBullet)`	`void`	Dispose/deactivate a bullet. Called by `<vanish>` nodes.

Enums

NodeName

Identifies the type of a BulletML XML element.

Value	XML Element	Description
`bulletml`	`<bulletml>`	Root document element.
`bullet`	`<bullet>`	Bullet definition with direction, speed, and actions.
`action`	`<action>`	Sequence of commands defining bullet behavior.
`fire`	`<fire>`	Fires a new bullet with optional direction/speed.
`direction`	`<direction>`	Direction value (with type modifier).
`speed`	`<speed>`	Speed value (with type modifier).
`changeDirection`	`<changeDirection>`	Gradually change direction over a duration.
`changeSpeed`	`<changeSpeed>`	Gradually change speed over a duration.
`accel`	`<accel>`	Apply acceleration (horizontal/vertical components).
`wait`	`<wait>`	Pause execution for N frames.
`repeat`	`<repeat>`	Repeat child actions N times.
`vanish`	`<vanish>`	Remove the bullet.
`horizontal`	`<horizontal>`	Horizontal acceleration component (inside `<accel>`).
`vertical`	`<vertical>`	Vertical acceleration component (inside `<accel>`).
`term`	`<term>`	Duration for changeDirection/changeSpeed/accel.
`times`	`<times>`	Repeat count.
`param`	`<param>`	Parameter value for referenced nodes.
`bulletRef`	`<bulletRef>`	Reference to a labeled `<bullet>`.
`actionRef`	`<actionRef>`	Reference to a labeled `<action>`.
`fireRef`	`<fireRef>`	Reference to a labeled `<fire>`.

NodeType

Modifier for direction and speed values.

Value	Description
`none`	No modifier (default).
`aim`	Direction aimed at the player position.
`absolute`	Absolute value (0 = up for vertical patterns, right for horizontal).
`relative`	Relative to the bullet's current direction or speed.
`sequence`	Added to the previous value each time the node fires.

PatternType

Orientation of the bullet pattern, set on the <bulletml> root element.

Value	Description
`vertical`	Bullets travel top-to-bottom. 0 degrees = down.
`horizontal`	Bullets travel left-to-right. 0 degrees = right.
`none`	No specific orientation.

RunStatus

Internal enum for task execution state.

Value	Description
`Continue`	Task is still running.
`End`	Task has finished.
`Stop`	Task has been stopped.

Delegates

PositionDelegate

public delegate Vector2 PositionDelegate();

Callback that returns a Vector2 position.

FloatDelegate

public delegate float FloatDelegate();

Callback that returns a float value.

FunctionDelegate

// From Equationator library
public delegate float FunctionDelegate();

Used for GameDifficulty and entries in CallbackFunctions. Returns a float value that can be referenced in BulletML expressions.