Unreal Engine Derived Data Cache Builder

BuildDDC.bat

:: Copyright (c) Solessfir under MIT license

:: This batch file builds the Derived Data Cache (DDC) for an Unreal Engine project.
:: It supports UE4, UE5, and custom engine setups.
:: Place this file in your project's root directory and run it.

@echo off

title Build Derived Data Cache
setlocal EnableDelayedExpansion

:: Set root directory to the script's location
set "RootDirectory=%~dp0"
set "RootDirectory=%RootDirectory:~0,-1%"

:: Locate the .uproject file in the current or parent directory
for %%i in ("%RootDirectory%\*.uproject") do (
  set "UprojectFilePath=%%~i"
  goto :UprojectLocationFound
)

cd ..
set "RootDirectory=%cd%"

for %%i in ("%RootDirectory%\*.uproject") do (
  set "UprojectFilePath=%%~i"
  goto :UprojectLocationFound
)

echo Error: No .uproject file found in %RootDirectory% or its parent directory.
goto :ExitWithPause

:UprojectLocationFound
echo Found .uproject file: %UprojectFilePath%

:: Extract EngineAssociation from the .uproject file
for /f "tokens=2 delims=: " %%a in ('findstr /i /c:"EngineAssociation" "%UprojectFilePath%"') do (
  set "EngineAssociation=%%a"
  set "EngineAssociation=!EngineAssociation:~1,-2!"
)

:: Check for custom engine (empty EngineAssociation)
if "!EngineAssociation!"=="" (
  echo Custom engine detected.
  :: Assume custom engine is located in ..\Engine relative to the project
  set "CustomEngineDir=%RootDirectory%\..\Engine"
  :: Check for UE4Editor-Cmd.exe (UE4) or UnrealEditor-Cmd.exe (UE5)
  if exist "%CustomEngineDir%\Binaries\Win64\UE4Editor-Cmd.exe" (
    set "UnrealEditor=UE4Editor-Cmd.exe"
    set "UnrealEditorPath=%CustomEngineDir%\Binaries\Win64\UE4Editor-Cmd.exe"
  ) else if exist "%CustomEngineDir%\Binaries\Win64\UnrealEditor-Cmd.exe" (
    set "UnrealEditor=UnrealEditor-Cmd.exe"
    set "UnrealEditorPath=%CustomEngineDir%\Binaries\Win64\UnrealEditor-Cmd.exe"
  ) else (
    echo Error: Could not find custom engine executable in %CustomEngineDir%\Binaries\Win64.
    goto :ExitWithPause
  )
) else (
  :: Truncate to major.minor version (e.g., 4.27.2 -> 4.27)
  for /f "tokens=1-2 delims=." %%a in ("!EngineAssociation!") do (
    set "EngineVersion=%%a.%%b"
  )
  echo Using Engine Version: !EngineVersion!
  :: Query registry for Unreal Engine installation directory
  set "EngineDirectory="
  for /f "skip=2 tokens=2*" %%a in ('reg query "HKEY_LOCAL_MACHINE\SOFTWARE\EpicGames\Unreal Engine\!EngineVersion!" /v "InstalledDirectory" 2^>nul') do (
    set "EngineDirectory=%%b"
  )
  if not defined EngineDirectory (
    echo Error: Couldn't find Unreal Engine installation for version !EngineVersion!.
    echo Ensure Unreal Engine !EngineVersion! is installed via the Epic Games Launcher.
    goto :ExitWithPause
  )
  :: Determine the editor executable based on engine version
  if "!EngineVersion:~0,1!"=="4" (
    set "UnrealEditor=UE4Editor-Cmd.exe"
  ) else (
    set "UnrealEditor=UnrealEditor-Cmd.exe"
  )
  set "UnrealEditorPath=!EngineDirectory!\Engine\Binaries\Win64\!UnrealEditor!"
)

:: Check if the editor executable exists
if not exist "!UnrealEditorPath!" (
  echo Error: Editor executable not found at !UnrealEditorPath!.
  goto :ExitWithPause
)

echo Unreal Editor Path: !UnrealEditorPath!
echo:

:: Run the command to build the Derived Data Cache
echo Building Derived Data Cache...
call "!UnrealEditorPath!" "!UprojectFilePath!" -run=DerivedDataCache -fill -DDC=CreatePak -ProjectOnly

:: Check if the build was successful
if !errorlevel! neq 0 (
  echo Error: Failed to build Derived Data Cache. Check the editor log for details.
) else (
  echo Derived Data Cache built successfully.
)

:ExitWithPause
pause
exit /b 0

endlocal