PortalPreview

Shows the place a wooden or stone portal leads to inside its frame. The destination is captured once as a frozen 3D scene and kept on disk, and the frame becomes a window onto it: the view has true parallax as you move, opens in a spiral as you approach, blends into the frame with a rippling edge and has smoke drifting along the seam.

The view follows the time of day and the weather at the destination: at night the far side is dark under the stars, in the morning the sun rises there too. The scene itself stays frozen (no moving creatures or particles). Between image updates the view is reconstructed from cached colour and depth instead of rendering the scene again. Steady test frames took around a millisecond on an RTX 4070 SUPER; frames that refresh the images cost more, and performance depends on the scene, resolution, movement and hardware.

Requirements

• Valheim with BepInEx 5 on Windows.

Recommended (optional)

• FastLoading: faster portal travel and dungeon entrances, so stepping through a portal takes a moment rather than a loading screen.
• ValheimVisuals: water, reflections, materials and ambient occlusion turned up within the game's own ranges, for a better picture everywhere.

Install

1. Close Valheim.
2. Put PortalPreview.dll into Valheim/BepInEx/plugins/.

Updating to 1.2.0

Replace the existing DLL while the game is closed. Keep your configuration and saved scenes: settings carry over (Capture mode becomes Snapshot updates; Resolution, Max visible portals and Max resident snapshots are kept if you used the Custom profile and follow the profile otherwise), and each saved view is captured once more on your next trip through its portal, or right away with frozenportal refresh next to it. The new water and ambient occlusion apply to saved views at once; Mistlands trees near a portal appear once its view has been captured again.

Closing portals retain their slot until the spiral completes. Expensive image updates are scheduled across frames. The newest physically matching archive wins even if a restored world changes portal IDs. Portable texture copies keep their full resolution; uncompressed HD packs can consume substantially more disk and video memory. Nearby water has its own surface and depth, using an isolated material rather than live-world screen-space effects.

How it captures

When a portal first shows its view: a portal shows the place at its other end, so that place has to be captured first, and only a place you are at can be.

• A new pair of portals: travel through it once. The portal you leave and the one you arrive at are both captured under that loading screen, and from then on both show their views.
• Two linked portals standing next to each other (a hub): both views appear a moment after linking, no trip needed.
• Portals built before installing the mod, or after a game update: the same as a new pair, one trip through each.
• A capture freezes the game for up to about a second, so it runs under the loading screen of a teleport through the portal: when you leave through it, or arrive at a portal that has no scene yet (the loading screen then stays up for at most four more seconds). Linked portals standing next to each other (a hub) are captured at once, so their views appear straight away; frozenportal refresh captures the portals next to you at once.
• Snapshot updates decides when an existing scene is replaced: WhenChanged (default) when you leave through the portal and something around it was built, removed, grown or dug since its last capture; EveryTrip on every departure (not again within two minutes); Once never, until frozenportal refresh.
• A capture waits for a fully black frame and may extend the transition. If it cannot start within three seconds, travel continues with the previous snapshot. A capture already in progress can take longer.
• Wooden and stone portals work in any pairing; the game links them to each other by tag.
• Saved scenes live in BepInEx/cache/PortalPreview/PortalSnapshots. Scenes and data nothing uses any more (a portal torn down, an older game version, what a recapture left behind) are removed automatically once per session.

Settings

BepInEx/config/ru.ivest.portalpreview.cfg, all live with Configuration Manager. The main ones:

Section	Setting	Default	Meaning
General	Enabled	true	Show portal views.
General	Hardware profile	Auto	Resolution, number of views and snapshots kept, from your video memory, RAM and CPU (Auto/Low/Medium/High/Ultra). Resolution, Max visible portals and Max resident snapshots follow it at 0 and override it for that setting alone when set above 0.
Portal preview	Preview quality	High	How often a visible portal renders its destination again as you move, its main cost; the image stays sharp. High: every 0.3 m. Medium: every 0.6 m. Both once more where you stop. Low: never (less exact parallax up close). Auto: Medium on the Low hardware profile.
Portal preview	Snapshot updates	WhenChanged	When a saved scene is replaced: when its surroundings changed (WhenChanged), on every departure (EveryTrip) or never (Once). Replaces Capture mode: DuringTeleport becomes EveryTrip, OnFirstLink WhenChanged.
Portal preview	Approach radius	15	How close to a portal its view opens, in metres.
Portal preview	Always visible	false	Show views at any distance while in sight.
Portal preview	One-sided view	false	Show the view only from the front, the side travellers come out of; from behind the portal looks as without the preview.
Portal preview	Spiral duration	1.2	Seconds the spiral takes to open or close.
Portal preview	Edge style	Ripple	How the picture meets the frame: Ripple, Vortex, Glow, Smoke or None.
Portal preview	Edge smoke	true	Smoke puffs along the seam between the view and the frame.
Portal preview	Panorama resolution	0	Sharpness of the distant landscape and clouds behind the scene: 0 by hardware profile (512 for Low and Medium, 1024 for High and Ultra), or 512, 1024, 2048. 2048 is about as sharp as the screen at 1440p, for about a second more per capture and about 100 MB more video memory per visible portal.
Portal preview	Follow time of day	true	Light the view for the time of day and the weather at its destination now. False keeps it as captured.
Portal preview	Hide game flames and fog	false	Hide the flames and dark swirling fog of the game's own connected-portal effect; its sparks, runes, light and sound stay. The picture then also sits at the front of the opening.

Console (F5): frozenportal status, on, off, refresh (recapture nearby portals), cleanup (remove stale saved scenes now), lighting (compare the lighting the mod computes where you stand with the game's own).

Errors and rate-limited warnings about preview work over 50 ms reach the log. For detailed captures, loads and frame costs, use frozenportal log on in the console (off with frozenportal log off), or launch with -portalpreview-log.

Limits

• Wooden and stone portals of the base game. Portals added by other mods keep their normal look.
• A destination nobody has visited in this installation has no view yet.
• The scene is frozen: no moving creatures or particles inside the frame.
• Views reconstructed between image updates can show small errors around thin objects or newly revealed edges.
• Frozen water does not reproduce all of the game's reflection, refraction and wave effects.
• Capturing and saving a new scene still requires synchronous work and can hitch; a render scheduler is not a frame-time guarantee. Full-resolution uncompressed texture packs cost more memory and disk than vanilla assets.
• Native Linux/Vulkan stability after repeated portal travel is not verified; this release does not claim to fix the reported Linux crashes.
• Time of day: the distant landscape and clouds were captured as pictures and are only brightened or darkened; falling rain or snow stays as captured; dungeon interiors keep their captured lighting; raids are not shown. Each lighting step redraws a visible portal's capture over a few frames, at most once per 10 seconds.

Multiplayer

Client-side. Each player captures the portals they use; nothing is sent over the network.

Problems and feedback

Write to me on Discord: https://discord.com/users/683075123816824940. Attach BepInEx/LogOutput.log from the game folder, or from the profile folder with a mod manager (r2modman: Settings → Browse profile folder), and say what you did when it happened. If a portal shows no view, add the output of frozenportal status typed in the F5 console next to it (the console needs the -console launch option), and start the game with -portalpreview-log so the log says what the preview did.