HDT Physics Extensions

skyrim — Mods & Enhancements

HDT Physics Extensions is an SKSE plugin that leverages Havok's physics engine to simulate real-time cloth, hair, and body physics in Skyrim, replacing static animations. It allows items like bikini armor straps, long hair strands, and skirts to sway and collide with the environment and body, while also enabling popular 'breast and buttock' physics via XML files. Players install it to add immersive, interactive physics that make the game feel modern, and it's a prerequisite for many adult and cosmetic mods.

Syntax

Patches

Example

Downloads: 7,414,079

💡 Notes

By HydrogensaysHDT

🎯 Tips & Tricks

Configuring physics XML files for custom armor

Navigate to 'Data\SKSE\Plugins\hdtPhysicsExtensionsDefaultBBP.xml' and edit the 'system' section to add new 'bone' entries. For example, to add physics to a custom necklace, copy the 'Necklace' bone block and adjust the 'stiffness' and 'damping' values (e.g., stiffness=50, damping=10) for desired sway. Save and restart the game. Use 'BodySlide' to preview changes.

Enabling physics for specific NPCs only

In the XML file, under 'system', add a 'group' tag with 'npc' attribute set to '1'. Then list the specific NPC's base ID (e.g., 'A2C94' for Serana) in the 'bones' section. This applies physics only to that NPC, reducing performance impact. Use the console command 'help serana' to find her base ID.

Fixing physics not working after changing body mods

Ensure you have the correct 'skeleton.nif' from XPMS installed. Then, in 'Data\SKSE\Plugins\hdtPhysicsExtensionsDefaultBBP.xml', check the 'bone' names match your body mod (e.g., CBBE uses 'Breast' and 'Breast01', UNP uses 'Breast' only). If not, edit the XML to rename 'Breast01' to 'Breast' or vice versa, and restart the game.

🔧 Troubleshooting

CTD when equipping armor with HDT physics, often due to conflict with 'HDT High Heels System' or 'HDT Equipment' mods.

Disable 'HDT High Heels System' temporarily, as it modifies the same skeleton nodes. If CTD persists, ensure you have the latest HDT Physics Extensions (14.28) and install 'HDT Physics Extensions Fixes' from the Nexus. Also, check that your armor mesh is using the correct bone names by opening it in NifSkope and comparing to the XML.

Physics cause severe FPS drop in crowded areas like Riften's market due to many NPCs with hair or cloth physics.

Reduce the 'maxSubSteps' and 'solverIterations' values in the XML file (e.g., set maxSubSteps=8, solverIterations=4) to lower CPU usage. Alternatively, use 'CBPC' (Collision Based Physics Collisions) as a lighter alternative, but if you must use HDT, set 'enablePhysics' to 'false' for distant NPCs via the 'group' tag in XML.

⚠️ Common Mistakes

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👍 Pros

237,446 endorsements

👎 Cons

Requires correct game version

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