launch.ps1

param([string]$GameDirectory='',[switch]$VerifyOnly)
$ErrorActionPreference='Stop'
$lastPath=Join-Path $PSScriptRoot 'work/last-install.json'
if(!(Test-Path -LiteralPath $lastPath)){throw 'Run Install Hitman VR.cmd first, and keep this extracted mod folder in place.'}
$last=Get-Content -LiteralPath $lastPath -Raw | ConvertFrom-Json
$m=Get-Content -LiteralPath $last.Manifest -Raw | ConvertFrom-Json
if(!$GameDirectory){$retail=[IO.Path]::GetFullPath($m.Retail)}else{
    $selected=[IO.Path]::GetFullPath($GameDirectory.Trim().Trim('"'))
    $retail=if(Test-Path -LiteralPath (Join-Path $selected 'HMA.exe')){$selected}else{[IO.Path]::GetFullPath((Join-Path $selected 'retail'))}
}
$exe=Join-Path $retail 'HMA.exe'
if((Get-FileHash -LiteralPath $exe -Algorithm SHA256).Hash -ne '5B93E0060C100197F658B7FC9D2F39323E3148396F7DE7CFF4496AAF4029952D'){throw 'Unsupported HMA.exe.'}
if(Get-Process HMA -ErrorAction SilentlyContinue | Where-Object Path -eq $exe){throw 'Hitman is already running. Close it before launching the VR test.'}
if($m.Retail -ne $retail){throw 'This game folder does not match the installed test.'}
foreach($item in $m.Files){
    # The INI is a user preference file, including the optional GI-off workaround.
    if($item.Relative -eq 'HitmanAbsolutionVR.ini'){continue}
    if((Get-FileHash -LiteralPath (Join-Path $retail $item.Relative) -Algorithm SHA256).Hash -ne $item.InstalledSHA256){throw "Installed payload changed: $($item.Relative)"}
}
if($VerifyOnly){Write-Output 'Installed binaries verified. User INI preferences may be edited.';return}
$ini=Get-Content -LiteralPath (Join-Path $retail 'HitmanAbsolutionVR.ini') -Raw
$useHeadsetResolution=!( $ini -match '(?im)^\s*UseHeadsetResolution\s*=\s*0\s*(?:;.*)?$' )
$registry='HKCU:\Software\IO Interactive\Hitman Absolution'
$displayBackup=$null
$oldEnvironment=@{}
try {
    if($useHeadsetResolution){
        $query=& (Join-Path $retail 'HitmanAbsolutionVR/HitmanAbsolutionVRHost.exe') --display-query
        if($LASTEXITCODE -ne 0){throw 'Could not query the headset resolution. Start the headset runtime, or set UseHeadsetResolution=0 in the INI.'}
        $display=$query | ConvertFrom-Json
        if($display.width -lt 1 -or $display.width -gt 16384 -or $display.height -lt 1 -or $display.height -gt 8192){throw 'Headset recommended resolution is outside the native transport limits.'}
        $environment=@{HITMAN_VR_EYE_WIDTH=[string]$display.width;HITMAN_VR_EYE_HEIGHT=[string]$display.height;HITMAN_VR_REFRESH_HZ=$display.refreshHz.ToString([Globalization.CultureInfo]::InvariantCulture)}
        foreach($name in $environment.Keys){$oldEnvironment[$name]=[Environment]::GetEnvironmentVariable($name,'Process');[Environment]::SetEnvironmentVariable($name,$environment[$name],'Process')}
        $values=@{ResolutionWidth=[int]$display.width;ResolutionHeight=[int]$display.height;Refreshrate=[int][Math]::Round($display.refreshHz);Fullscreen=1;ExclusiveFullscreen=1;VSync=0;WindowWidth=[int]$display.width;WindowHeight=[int]$display.height;Aspectratio=0}
        $saved=Get-ItemProperty -LiteralPath $registry
        $displayBackup=@()
        foreach($name in $values.Keys){$value=$saved.PSObject.Properties[$name];$displayBackup+=@{Name=$name;Existed=($null -ne $value);Value=if($value){$value.Value}else{$null};Applied=$values[$name]}}
        $backupDirectory=Join-Path $PSScriptRoot 'work/display-settings'
        New-Item -ItemType Directory -Force -Path $backupDirectory | Out-Null
        $displayBackup | ConvertTo-Json | Set-Content -LiteralPath (Join-Path $backupDirectory ((Get-Date -Format 'yyyyMMdd-HHmmss-fff')+'.json'))
        foreach($name in $values.Keys){New-ItemProperty -LiteralPath $registry -Name $name -PropertyType DWord -Value $values[$name] -Force | Out-Null}
        Write-Output "Native headset render size: $($display.width)x$($display.height) per eye."
    }
    $game=Start-Process -FilePath $exe -WorkingDirectory $retail -PassThru
    $game.WaitForExit()
} finally {
    foreach($item in $displayBackup){
        $now=Get-ItemPropertyValue -LiteralPath $registry -Name $item.Name -ErrorAction SilentlyContinue
        if($now -eq $item.Applied){
            if($item.Existed){New-ItemProperty -LiteralPath $registry -Name $item.Name -PropertyType DWord -Value $item.Value -Force | Out-Null}
            else{Remove-ItemProperty -LiteralPath $registry -Name $item.Name}
        }
    }
    foreach($name in $oldEnvironment.Keys){[Environment]::SetEnvironmentVariable($name,$oldEnvironment[$name],'Process')}
}