Bow Trajectory

A lightweight, client-side Valheim mod that draws the predicted flight path of your arrow/bolt in real time while you draw a bow (or aim a crossbow), ending in a marker where it's predicted to land.

It reads the real launch values from the game each frame (draw strength, projectile speed, gravity, drag) and simulates the exact same physics the projectile uses, so the line matches where the arrow will actually go.

• Purely visual / client-side. It does not change any gameplay values, so it's safe in single-player and on servers that don't have the mod installed.
• Works with bows and crossbows, and adapts to your current ammo (different arrows have different speeds/gravity).

Requirements

• Valheim (PC)
• r2modman (or Thunderstore Mod Manager) with a Valheim profile that has BepInExPack Valheim installed
• For building from source: the .NET SDK (8.0+)

Install with r2modman

1. Install r2modman, choose Valheim, and create (or select) a profile.
2. In that profile, install BepInExPack Valheim (r2modman pulls it in as a dependency for most mods; if it isn't there, install it from the Online tab).
3. Launch the game once through r2modman (Start Default) so the profile's BepInEx folders are generated.
4. Drop BowTrajectory.dll into the profile's plugins folder: %APPDATA%\r2modmanPlus-local\Valheim\profiles\<ProfileName>\BepInEx\plugins\ (or import it via r2modman's Import local mod).
5. Launch Default and equip a bow.

If you build from source (below), the build copies the DLL into your profile automatically.

Show it in the r2modman mod list (Import local mod)

r2modman only lists mods that were installed through it. To have it appear and be managed (recommended), import the packaged zip:

1. Build the package: dotnet build -c Release -t:Package (produces dist\BowTrajectory-<version>.zip).
2. In r2modman, select your profile, then Settings -> Import local mod and choose that zip.
3. Start Default.

Do not also drop the loose DLL into BepInEx\plugins\ when using the imported version, or BepInEx will see the plugin twice (duplicate GUID) and skip loading it.

Usage

1. Equip a bow or crossbow and select arrows/bolts.
2. Hold to draw the bow — the trajectory line appears and updates as your draw strength increases. For crossbows it appears while aiming.
3. Release to fire; the arrow follows the predicted path.
4. Press B in-game to toggle the preview on/off (configurable).

Configuration

Settings live in the BepInEx config file and can also be edited live with a config manager mod. File location: %APPDATA%\r2modmanPlus-local\Valheim\profiles\<ProfileName>\BepInEx\config\ModdedWolf.BowTrajectory.cfg

For manual BepInEx installs, the file is at: Valheim\BepInEx\config\ModdedWolf.BowTrajectory.cfg

Updating from v1.0.2 or earlier: config moved from dev.modded.bowtrajectory.cfg to ModdedWolf.BowTrajectory.cfg. Your settings are copied over automatically the first time you run v1.0.3+. You can delete the old file once everything looks right.

How it works

Each frame, while a bow/crossbow is drawn, the mod:

1. Reads the launch point and aim direction the game would use (Attack.GetProjectileSpawnPoint).
2. Computes the launch speed from the bow's m_projectileVel/m_projectileVelMin and the current draw percentage via the bow's m_drawVelocityCurve (plus any bonus from the selected ammo).
3. Reads m_gravity/m_drag from the arrow's projectile prefab.
4. Steps the projectile forward using the same integration as Projectile.FixedUpdate (vel += down * gravity * dt, quadratic drag, pos += vel * dt) at the game's live Time.fixedDeltaTime, raycasting each segment against terrain/structures until it hits something.
5. Feeds the points into a LineRenderer and places the impact ring at the first hit.

Notes

• Accuracy spread is intentionally ignored so the line shows the true center aim, not the random cone.
• Built against your installed Valheim version's assemblies. After a major Valheim update, rebuild from source if member names changed.

Questions or bugs? Discord

Changelog

1.0.6

• Moved in-game settings onto a dedicated Settings → Bow Trajectory tab (vanilla Accessibility layout is unchanged).
• Tab includes toggles for show trajectory, show impact marker, and show for crossbows.
• Tab includes trajectory color and impact marker color dropdowns (Custom hex still uses Configuration Manager / the cfg file).
• Added Line width and Impact marker size sliders on the tab (same ranges as Configuration Manager).
• Color dropdowns stay at the narrower ~180px width for a cleaner layout.
• Added a Default button (centered at the bottom of the settings content) that resets all tab settings to Bind defaults and saves.
• Fixed duplicate white floating label on the Bow Trajectory settings tab button (leftover TMP from cloning Accessibility).
• Fixed Bow Trajectory tab caption staying orange when unselected (restored vanilla Selected on/off caption colors).

1.0.5

• Color settings (StartColor, EndColor, ImpactColor) are now named presets (dropdown in Configuration Manager) instead of raw Unity colors.
• Preset dropdown shows friendly labels (e.g. RGB Cycle Fast, Custom) instead of raw enum names like RgbCycleFast.
• Added matching *ColorHex settings (#RRGGBB or #RRGGBBAA) used when the preset is Custom.
• Animated RGB Cycle Slow / Medium / Fast presets cycle through rainbow hues (~7s / ~3.5s / ~1.25s per full rotation).
• Config scrub: bare hex (e.g. FFFFFFD9) and legacy Unity Color values left in preset keys are converted to Custom + hex before Bind, so BepInEx no longer warns that values like FFFFFFD9 were not found.

1.0.4

• Fixed config migration re-applying on every startup: after a successful migration, legacy dev.modded.bowtrajectory.cfg is renamed to dev.modded.bowtrajectory.cfg.migrated so migration only runs once and no longer overwrites user edits to ModdedWolf.BowTrajectory.cfg.

1.0.3

• Renamed plugin GUID to ModdedWolf.BowTrajectory (config path is now ModdedWolf.BowTrajectory.cfg)
• Migrates settings from legacy dev.modded.bowtrajectory.cfg on first launch

1.0.0

• Initial release