Add option to build plugins against different versions of UE

doc/BuildPlugin.md

@@ -15,6 +15,9 @@ Usage:
   -src          : Source folder (current folder if omitted)
                 : (should be root of project)
   -allplatforms : Build for all platforms, not just the current one
+  -allversions  : Build for all supported UE versions, not just the current one"
+                : (specified in pluginconfig.json, only works with lancher-installed UE)"
+  -uever:5.x.x  : Build for a specific UE version, not the current one (launcher only)"
   -dryrun       : Don't perform any actual actions, just report on what you would do
   -help         : Print this help
 
@@ -33,7 +36,25 @@ in the root of your plugin, next to the .uplugin file. The options are:
     "PackageDir": "C:\\Users\\Steve\\Marketplace",
     "BuildDir": "C:\\Users\\Steve\\Builds\\MyPlugin",
     "PluginFile": "OptionalPluginFilenameWillDetectInDirOtherwise.uplugin",
+
+    "EngineVersions":
+    [
+        "5.1.0",
+        "5.2.0"
+    ]
+
+
 }
 ```
 
 Only `BuildDir` is required.
+
+The `-allversions` option only works with Launcher installed engines,
+since the path is derived from UEROOT. If using non-Launcher engines, or you
+need to change some other environmental options per version (e.g. setting
+`LINUX_MULTIARCH_ROOT` environment var), then you're recommended to instead
+use the `-uever:` option to build one version at a time, and set the environment
+(including `UEINSTALL`) specifically for each version.
+
+This script will, however, handle changing the EngineVersion in the .uplugin
+during the build, and resetting it afterwards.

inc/uplugin.ps1

@@ -32,3 +32,15 @@ function Get-Uplugin-Filename {
         return $projfile
     }
 }
+
+function Update-UpluginUeVersion {
+    [string]$srcfolder,
+    [PluginConfig]$config,
+    [string]$version
+
+    $pluginfile = Get-Uplugin-Filename $srcfolder $config
+    $plugincontents = (Get-Content $pluginfile) | ConvertFrom-Json
+    $proj.EngineVersion = $version
+    $newjson = ($plugincontents | ConvertTo-Json -depth 100)
+    $newjson | Out-File $pluginfile
+}

ue-build-plugin.ps1

@@ -3,6 +3,8 @@ param (
     [string]$mode,
     [string]$src,
     [switch]$allplatforms = $false,
+    [switch]$allversions = $false,
+    [string]$uever = "",
     [switch]$nocloseeditor = $false,
     [switch]$dryrun = $false,
     [switch]$help = $false
@@ -23,6 +25,9 @@ function Print-Usage {
     Write-Output "  -src          : Source folder (current folder if omitted)"
     Write-Output "                : (should be root of project)"
     Write-Output "  -allplatforms : Build for all platforms, not just the current one"
+    Write-Output "  -allversions  : Build for all supported UE versions, not just the current one"
+    Write-Output "                : (specified in pluginconfig.json, only works with lancher-installed UE)"
+    Write-Output "  -uever:5.x.x  : Build for a specific UE version, not the current one (launcher only)"
     Write-Output "  -dryrun       : Don't perform any actual actions, just report on what you would do"
     Write-Output "  -help         : Print this help"
     Write-Output " "
@@ -64,23 +69,39 @@ try {
     }
 
     $proj = Read-Uproject $pluginfile
-    $ueVersion = Get-UE-Version $proj
-    $ueinstall = Get-UE-Install $ueVersion
+    $origUeVersion = Get-UE-Version $proj
+    if ($allversions) {
+        $ueVersions = $config.EngineVersions
+    } elseif ($uever.Length -gt 0) {
+        $ueVersions = @($uever)
+    } else {
+        $ueVersions = @($origUeVersion)
+    }
+
     
     Write-Output ""
-    Write-Output "Project File    : $projfile"
-    Write-Output "UE Version      : $ueVersion"
-    Write-Output "UE Install      : $ueinstall"
+    Write-Output "Project File    : $pluginfile"
+    Write-Output "UE Version(s)   : $($ueVersions -join `", `")"
     Write-Output "Output Folder   : $($config.BuildDir)"
     Write-Output ""
 
-    $runUAT = Join-Path $ueinstall "Engine/Build/BatchFiles/RunUAT$batchSuffix"
+    foreach ($ver in $ueVersions) {
 
+        Write-Output "Building for UE Version $ver"
+        $ueinstall = Get-UE-Install $ver
+        $outputDir = Join-Path $config.BuildDir $ver
+
+        # Need to change the version in the plugin while we build
+        if (-not $dryrun -and ($allversions -or $ueVer.Length -gt 0)) {
+            Update-UpluginUeVersion $src $config $ver
+        }
+
+        $runUAT = Join-Path $ueinstall "Engine/Build/BatchFiles/RunUAT$batchSuffix"    
 
         $argList = [System.Collections.ArrayList]@()
         $argList.Add("BuildPlugin") > $null
         $argList.Add("-Plugin=`"$pluginfile`"") > $null
-    $argList.Add("-Package=`"$($config.BuildDir)`"") > $null
+        $argList.Add("-Package=`"$outputDir`"") > $null
         $argList.Add("-Rocket") > $null
 
         if (-not $allplatforms) {
@@ -97,10 +118,20 @@ try {
         } else {            
             $proc = Start-Process $runUAT $argList -Wait -PassThru -NoNewWindow
             if ($proc.ExitCode -ne 0) {
+                # Reset the plugin back to the original UE version
+                if ($allversions -and -not $dryrun) {
+                    Update-UpluginUeVersion $src $config $origUeVersion
+                }
+
                 throw "RunUAT failed!"
             }
         }
+    }
 
+    # Reset the plugin back to the original UE version
+    if ($allversions -and -not $dryrun) {
+        Update-UpluginUeVersion $src $config $origUeVersion
+    }
 
     Write-Output "-- Build plugin process finished OK --"