2D Projectiles plugin for Godot 4

More materials, e.g. demo project can be found in .

Overview

This addon provides the functionallity for simple 2D bullets/projectiles system, similar to ones seen in games such as Enter the Gungeon, The Textorcist, or other "lighter" bullethell games. Bullet patterns can be created/modified with dedicated editor.

Installation

To add this plugin to your Godot 4 project:

• copy the folder ./addons/projectiles_plugin/ into your project's addons/ folder (create it if it's not there)
• enable the plugin in Project->Project settings...->Plugins menu Godot

If you've added it correctly, new editor view called Projectiles Editor should be available in the bottom dock.

Limitations

This project has been created with fast prototyping and ease of game content creation/modification as a top priority. The performance may be luckluster for more demanding applications.

Functionality

The following types of objects are defined in this addon:

• Projectile: bullet travelling in 2D space; can hit objects.
• Trajectory: path, along which the Projectile is moving.
• Pattern: defines all of the Projectiles that are fired at the same time, e.g. shotgun-like patter may contain 5 bullets at angles -40, -20, 0, 20 and 40.
• Pattern Element: a sort of "spawner" for single bullet inside a given pattern.
• Pattern Shooter: object that can fire an assigned Pattern.

Trajectories

The following basic trajectories are defined:

• LinearTrajectory2D: projectiles travel in straight line:

• CircularTrajectory2D: projectiles orbit around a point:

• ZigzagTrajectory2D: projectiles oscillate around a point:

The CombinedTrajectory2D makes it possible to move projectile along two or more trajectories at once. For example, the sinusoidal path can be constructed by combining LinearTrajectory2D and ZigzagTrajectory2D:

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New user-defined trajectories can be created by inheriting Trajectory2D class and providing get_delta(delta: float, total_time: float) -> Vector2: function. This function should return the 2D displacement between trajectory position in time total_time and total_time + delta.

Projectiles

Projectiles can hit objects. By default the bulles look for damage(dmg: float) -> void: function in objects they hit and invoke it. After hitting anything, the projectile is freed, regardless of whether the target has damage() method or not.

The custom behaviour can be achieved by inheriting Projectile2D and providing _on_body_entered(body: Node2D) -> void: function.

Projectile2D class exposes the following signals:

• body_hit(projectile: Projectile2D, body: Node2D) - emitted whenever a projectile hits something.
• max_range_reached(projectile: Projectile2D) - emitted when a projectile reaches it's assigned range and is about to be freed.

Pattern Elements

Projectiles are spawned on PatternElement2Ds and have their properties defined by them. Each element can create only one bullet when firing a pattern, but two or more elements can be placed on the same position.

The following properties of projectiles can be controlled by PatternElement2Ds:

Property	Description
projectile	Projectile2D scene that is spawned by element
position	Determines where the projectile is spawned
angle	Direction, at which the bullet is fired
trajectory	Path, along which the projectile travels
speed	How fast the bullet travels
speed_ramp	How the speed of the bullet changes as it travels. If speed_ramp is set, it takes precedence over speed setting. The ramp should be defined for [0, range] on X axis.
range	How far the bullet will travel
spawn_delay	Time, after which the bullet will be spawned
travel_delay	After the bullet is spawned, travel_delay will define how long it will take for the bullet to start moving.
rand_spread	How much the angle will be randomized when firing the bullet
target_group	When defined, the bullet will be fired in the direction of the closest object from specified group

Pattern Shooters

position and rotation of this node influence the origin where the pattern is fired and directions of projectiles.

Two Pattern Shooters are available:

• PatternShooter2D - simply fires a given pattern.
• TargetedShooter2D - automatically rotates in the direction of the closest node from group specified by group_name parameter.

Two signals are available for Pattern Shooters:

• new_projectile_fired(projectile: Projectile2D) - emitted after each projectile is fired.
• all_fired() - emitted after all of the projectiles in assigned Pattern2D have been fired.

Note: if a given pattern uses spawn_delay, signal all_fired will be emitted only after the last projectile has been spawned (after time = max spawn_delay from all of the PatternElement2Ds).

Editor

The Projectiles Editor is located in the Godot Editor's bottom dock. It should automatically open when Pattern2D resource is selected in the Inspector.

For most actions, keyboard shortcuts are available. Keybindings can be changed by editing keybindings in /addons/projecitles_plugin/projectiles_plugin.gd. The default actions are as follows:

Action name	Default shortcut	Description
move_elem	A	Move an element around
rotate_elem	S	Rotate element
duplicate_elem	D	Duplicate selected elements
select_all	F	Select all of the elements
toggle_snapping	Z	Turn snapping to grid ON/OFF
test_pattern	X	Visualize the pattern in the editor, the same way it will look when fired in a game
remove_elems	Delete	Deletes selected elements
modify_s_delay	Q	Turns on spawn_delay modification. After using this shortcut, use mouse wheel to adjust the value. Hold Alt or Shift to adjust how fast the value is changing.
modify_t_delay	W	Turns on travel_delay modification. After using this shortcut, use mouse wheel to adjust the value. Hold Alt or Shift to adjust how fast the value is changing.
modify_speed	E	Turns on speed modification. After using this shortcut, use mouse wheel to adjust the value. Hold Alt or Shift to adjust how fast the value is changing.
modify_range	R	Turns on range modification. After using this shortcut, use mouse wheel to adjust the value. Hold Alt or Shift to adjust how fast the value is changing.
rotate_parallel	1	Rotates selected elements to point into mouse direction, in a way that keeps those directions parallel to each other
rotate_focused	2	Rotates selected elements, so that each of them points into mouse directly
rotate_inwards	3	Rotates selected elements to point into the origin of edited pattern
rotate_outwards	4	Rotates selected elements to point in the opposite direction to the origin of edited pattern
rotate_random"	5	Rotates selected elements by random value

Additionally, the view can be moved around by holding Middle Mouse Button (scroll wheel).

The view can be zoomed in/out by holding Ctrl and using scroll wheel.

Future work

• Move some/all functionality of projectiles handling (not editor and it's features) to GDNative extension/C++ compiled code for improved performance.
• Undo/redo support.