PDM - Preprocessor Directive Manager

PDM (Preprocessor Directive Manager) is a Unity Editor tool that automatically defines C# preprocessor directives based on the presence of packages, namespaces, or classes in your project. It is part of the YJack framework.

Overview

When developing Unity projects with optional dependencies (e.g., Oculus VR, Universal Render Pipeline, LiteNetLib), you often need to wrap code in #if preprocessor directives to avoid compilation errors when a package is not installed. PDM automates the management of these directives by:

1. Scanning loaded assemblies for specified namespaces, classes, or UPM packages
2. Automatically updating scripting define symbols via PlayerSettings.SetScriptingDefineSymbols with NamedBuildTarget
3. Recompilation is triggered automatically by Unity when defines change

Installation

Via Unity Package Manager (Git URL)

1. Open Unity and go to Window > Package Manager
2. Click the + button and select Add package from git URL...
3. Enter: https://github.com/YvesAlbuquerque/PDM_Core.git
4. Click Add

Manual Installation

1. Clone or download this repository
2. Copy the contents into your Unity project's Packages/com.ygamedev.pdm/ directory

Usage

Lookup Types

PDM supports three domain types for detection:

Domain Type	Description	Example Lookup Value
Namespace	Checks if a namespace exists in any loaded assembly	Unity.Netcode
Class	Checks if a class name exists in any loaded assembly	OVRManager
Package	Checks if a UPM package is installed by package name	com.unity.render-pipelines.universal

Tip: For UPM packages, prefer the Package type over Namespace — it's more reliable since it checks the package registry directly via PackageInfo.FindForAssetPath rather than scanning assembly types.

Default Configuration

PDM comes with a pre-configured PreprocessorDirectiveDefiner asset that includes common directive mappings. The default directives include:

Namespace/Class	Directive Defined	Description
UnityStandardAssets.ImageEffects	STANDARD_IMAGE_EFFECTS_EXIST	Standard image effects
OVRManager	USING_OVR	Oculus VR integration
UnityEngine.Analytics	ANALYTICS	Unity Analytics
Unity.RemoteConfig	REMOTECONFIG	Remote Config service
LiteNetLib	LITENETLIB	LiteNetLib networking
Unity.Netcode	NETCODE	Netcode for GameObjects
Unity.Netcode.Transports.UNET	UNET_TRANSPORT	UNET Transport
Unity.Services.Core	UNITY_SERVICES	Unity Services
UnityEngine.Rendering.Universal	URP	Universal Render Pipeline
Unity.EditorCoroutines	EDITORCOROUTINES	Editor Coroutines
InstaLOD	ENABLE_INSTALOD	InstaLOD integration
Unity.Sentis	UNITY_SENTIS	Unity Sentis AI

Custom Configuration

To add your own directive mappings:

1. Select the PreprocessorDirectiveDefiner asset in your project
2. Add entries to the Look Up Code array:
   • Domain Type: Choose Namespace, Class, or Package
   • If Exist: The namespace, class name, or UPM package name to look for
   • Define: The preprocessor directive to define when found

How It Works

• PDM runs automatically when the Unity Editor loads (via [InitializeOnLoadMethod])
• It also re-runs whenever packages are registered or unregistered via the UPM
• Detected directives are set via PlayerSettings.SetScriptingDefineSymbols using NamedBuildTarget, making them visible in Project Settings > Player > Scripting Define Symbols
• You can manually trigger a refresh using the Apply Directives context menu on the asset
• PDM re-runs on domain reload (including after build target switches), so defines are kept up to date

Using Directives in Code

Once PDM defines a directive, you can use it in your C# code:

#if USING_OVR
    // Oculus VR specific code
    OVRManager.instance.Initialize();
#endif

#if URP
    // Universal Render Pipeline specific code
    var renderPipelineAsset = GraphicsSettings.renderPipelineAsset;
#endif

Optional: Odin Inspector Support

If you have Odin Inspector installed and the ODIN_INSPECTOR define is set, the DirectiveDefiner asset will display an Apply button in the Inspector for easy manual refresh.

Migration from v1.1.x

PDM v1.2.0 replaces the csc.rsp file approach with Unity's PlayerSettings.SetScriptingDefineSymbols API:

• Defines are now visible in Project Settings > Player > Scripting Define Symbols
• No more generated files — the Assets/csc.rsp file is no longer written. You can safely remove any PDM-generated csc.rsp from your project.
• Minimum Unity version is now 2021.3 LTS (required for the NamedBuildTarget API)
• New Package domain type allows direct UPM package detection by name

Requirements

• Unity 2021.3 LTS or later

License

BSD 2.0 - See LICENSE.md for details.

Author

Created by Yves J. Albuquerque