wip Real-Time Body Physics (DirectX 11)

[CPVC]

Real-Time Body Physics (DirectX 11)

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Real-Time Body Physics is a highly experimental mod for the Sims 4 that attempts to add real-time body physics to sims. Currently, only the breasts and butt are targeted, but other parts could be added in the future.

 

The mod works via a fake DirectX DLL that behaves just like the real deal, but injects a little extra code into the rendering loop (See: https://en.wikipedia.org/wiki/Hooking).

 

Please read the included "ReadMe.html" file before using this mod. It explains how to install, configure, and control the mod in-game.

 

RTBP 11 (DirectX 11):

 

RTBP for DirectX 11 is now available. You can expect all functionality from the DirectX 9 version in RTBP11, but the better performance of the Sims 4's newer DirectX 11 renderer.

 

https://streamable.com/0ukdjd

 

Be warned that it is a little buggy compared to the DirectX 9 version, but things should improve with time. DirectX 11 is quite a bit more complicated than DirectX 9, so getting everything working has been more of an ordeal. Most of the bugs are very minor, small visual glitches while everything else appears to be solid as a rock. That being said, don't forget to save often and backup your save games.

 

Hopefully the small visual bugs aren't deal breakers for most of you. If they are, you can eliminate almost all of them by disabling butt physics.

 

If you haven't used the internal GUI yet, try it out in game by pressing F11. The internal GUI will eventually replace the Commander, but for the time being both can be used to tweak RTBP to your liking.

 

 

To avoid confusion, I'm calling this release RTBP v2.0. That way you'll know that and RTBP release with a version number of 2.0 and above is the DirectX 11 version and anything below is DirectX 9.

 

Known Issues:
* For some meshes, one of the butt cheeks looks deflated and sags downward.
* Some sims glich out and their geometry shoots out in random directions.
* Sims might look a little weird in the portrait images.

* Probably more.

 

These issues ought to be fixed in time. Let me know if you have any problems. Please enjoy and have a happy new year.

 

Real-Time Body Physics

 

Experimental Builds

 

Fixing bugs can be difficult, especially when you can't reproduce the error that has befallen so many users. If you're up for it, try out an experimental build in testing and report your findings in the support thread.

 

2026-05-04: Built with Clang-CL.

 

RTBP v2.2~4 2026-05-04 (Clang-CL).zip

 

RTBP Legacy (DirectX 9, Depreciated):

 

The DirectX 9 version of RTBP has been superseded by the DirectX 11 version and is no longer being developed. Use the DirectX 9 version only if you have to.

RTBP v0.4-p8 2024-04-12.zip

 

Note for those with an Intel GPU:

You'll need to tweak a Sims 4 configuration file for RTBP to work. Go to your game installation directory + "/Game/Bin/" (the same place you put "d3d9.dll"), and open the file "GraphicsRules.sgr". Find the line that says "setProp $ConfigGroup EnableSoftwareSkinning true" (for me it was on line 117) and replace the part that says "true" to "false".

 

This will enable hardware skinning for Intel hardware and allow RTBP to work.

 

Note on DirectX 11:

A recent update added DirectX 11 support to the Sims 4. RTBP was designed around the original version of the game that uses DirectX 9. For RTBP to function, the D3D9 version of the game needs to be used (D3D11 support is coming). To explicitly launch the D3D9 version of the Sims 4, find your installation directory and execute "...\Game\Bin\TS4_DX9_x64.exe". You can also choose to switch to the D3D9 version of the game in the game options.

 

 

Bonus: If you'd like, you can try out the super duper, highly experimental, RTBP GUI tool that allows you to Alt+Tab out of the game and change settings on the fly via the RTBP Command Server using a user friendly GUI interface:

 

 

* Screenshot is out of date.

 

The RTBP GUI Tool is a work in progress and more features will be added soon. Beware that you can send values to RTBP that might break it and cause body parts to disappear.

 

 

Bonus 2: Having a bit of trouble installing RTBP? Try out the RTBP installer. Just select the RTBP zip file you'd like to install, your Sims 4 installation directory, and your Sims 4 mods directory. The RTBP Installer will attempt to automatically detect these paths, so if you're unsure, I recommend going with the default values.

 

Update 2023-11-11: The new versions of the RTBP Commander and Installer have been bundled to save space. Note that this version of the installer is incompatible with older versions of RTBP. Download both of them here:

 

 

 

 

Update 2023-04-01: Origin has been depreciated and replaced with the EA App. The RTBP installer will no longer look for your Sims 4 installation in the Origin game directory.

Update 2023-03-24: Added the EA App game installation directory to the list of potential Sims 4 game installation directories. The requisite libraries required for RTBP to function will be individually tested during installation.

Update 2022-08-13: The RTBP Installer should now detect when GShade is installed and make the changes necessary for RTBP compatibility.

Update 2022-07-26: Improved logging.

Update 2021-11-18: The RTBP Installer now has an uninstallation wizard.

 

Bonus 3: Looking for a more bleeding edge version of RTBP? Download the latest preview and/or experimental release here. These releases need to be manually installed, so they're for more advanced users. Documentation and script mods aren't typically included with these:

 

RTBP v0.4-p9-e3 2025-12-11.zip

RTBP GUI Tools 2026-03-04.zip

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• Submitter
  CPVC
• Submitted
  09/01/20
• Category
  Extensions
• Requirements
  The Sims 4 (64 bit)

 

Edited December 13, 2021 by CPVC
Outdated screenshots disclaimer added.

[youngmusclefan]

does this affect mens' butts too or just womens'?

[ColonolNutty]

When editing the description, I'd suggest hitting that "View File" link/button at the top of your first post and editing it there. (The View File button will look like a Link like it does now otherwise)

[CPVC]

29 minutes ago, youngmusclefan said:

does this affect mens' butts too or just womens'?

Yes it affects both unfortunately. I'd like to add an option to turn it off based on gender, but I haven't found a way to distinguish male from female meshes yet. I'll work on it.

[2cool4u_1]

4 minutes ago, Skyrim4DERS said:

will this conflict with sex animations? 
....
Also if possible and based on the videos tone the jiggle WAAAAY down (or at least make presets for different tastes)

It adds to the animation, whether or not the animation has breast movement. The jiggle in the videos are for demonstration. You have the option to adjust some of the settings yourself, so you can customize it precisely to your tastes.

[CPVC]

39 minutes ago, Skyrim4DERS said:

The future is now old man!


As cool as this is and excited to see its further development, will this conflict with sex animations? 

Also if possible and based on the videos tone the jiggle WAAAAY down (or at least make presets for different tastes)

But keep at it! Looks super promising already

Yes, the default variables for the physics simulators really do need to be toned down a bit. Honestly, I haven't spent a lot of time tuning them. I was hoping one of the beta testers could play around with the values and suggest some that were reasonable.

 

You can change them by editing the Settings.ini file or through the cheat console if you installed the optional cheats mod. Note that the cheat console method doesn't work in Create A Sim. Script mods don't get loaded until you're actually in game.

 

In the future, I'd like the variables to be computed automatically based on the actual physical characteristics of the body parts. For example, bigger breasts are going to have more mass than smaller ones.

[Cataclysimz]

2 hours ago, CPVC said:

Yes it affects both unfortunately. I'd like to add an option to turn it off based on gender, but I haven't found a way to distinguish male from female meshes yet. I'll work on it.

Why "Unfortunately"? Lol. This is a good thing. I'd say you're better off focusing on improving other aspects of the mod. 

[LukePHils]

Do you have plans to do Penis Physics too? Kind of like Floppy SOS in Skyrim. 

[babblonin]

man ive been looking for smt like this for a long time, since there are like no currently working butt physics mods for the sims 4, id be happy to know if there are any others but this looks promising, might be one of the new top nsfw mods for ts4 in the future if it get tweaked some more, keep it up ?.

[CPVC]

6 minutes ago, The_FDS said:

I use Reshade and it uses the same d3d9.dll. Is there a way to change the name ? I tried to change the name of the dll reshade uses with ENBInjector.exe with no luck. If anyone can find a way to run both, let me know!

Put the Reshade d3d9.dll in the RTBP folder in "The Sims 4/Game/Bin". The mod looks for the "real" d3d9.dll there first before loading the system one, just for situations like this.

 

Please let me know if it works. I haven't tested it.

[JonGuiDoe]

22 hours ago, LukePHils said:

Do you have plans to do Penis Physics too? Kind of like Floppy SOS in Skyrim. 

I, too, would like to see floppy flaccid sim dongers ?

[ColonolNutty]

Both Male and Futanari Sims too!

[Kodenu]

On 9/1/2020 at 9:32 PM, CPVC said:

Yes, the default variables for the physics simulators really do need to be toned down a bit. Honestly, I haven't spent a lot of time tuning them. I was hoping one of the beta testers could play around with the values and suggest some that were reasonable.

 

You can change them by editing the Settings.ini file or through the cheat console if you installed the optional cheats mod. Note that the cheat console method doesn't work in Create A Sim. Script mods don't get loaded until you're actually in game.

 

I started playing around with the values in the Settings.ini and came up with some interesting results. Through experimentation this is what I came up with. These settings make the movements much less exaggerated and under control. The butt settings are very close to what I would consider more realistic. Watching them move up the stairs and the butt jiggle instead of wildly bounce all over the place is nice. I have the breasts better under control and still messing around with them somewhat. The frontal horizontal movement is still a bit excessive to me.  I'm sure as you advance on this some things will iron themselves out.

 

[rtbp.general]
startCommandServer=true
enableBreastPhysics=true
enableButtPhysics=true

[rtbp.leftBreast]
mass=0.5
damping=30.0
springK=200.0
maxLength=0.1

[rtbp.rightBreast]
mass=0.5
damping=30.0
springK=200.0
maxLength=0.1

[rtbp.leftButt]
mass=0.5
damping=8.0
springK=300.0
maxLength=0.2

[rtbp.rightButt]
mass=0.5
damping=8.0
springK=300.0
maxLength=0.2

 

[CPVC]

On 9/2/2020 at 1:48 AM, LukePHils said:

Do you have plans to do Penis Physics too? Kind of like Floppy SOS in Skyrim. 

Once I get everything perfected, I'll add physics to whatever body parts people want. I probably won't be adding any new body parts soon, because my priority now is squashing bugs.

[CPVC]

Squashed a major bug this evening. Hopefully bouncing fingers and faces will be a thing of the past now. Turns out I was looking for the bug in the wrong place.

[GarbageNameHere]

MEGA HYPE! (And ultra hopes for the best!) ?

[CPVC]

Might as well release a new preview.

 

You should (hopefully) encounter much less bugs. Breast detection appears to be near perfected. Butt detection less, so. Sometimes you still get bouncy fingers. Still working on that.

 

The Settings.ini file has been updated with more reasonable variables, but updating is optional. If you have your own custom variables, you can keep your old Settings.ini file.

 

I'll publish a new release with source code once I get the last few nagging bugs taken care of.

RTBP Preview 2020-09-05.zip

[Veoly]

On 9/3/2020 at 4:09 AM, CPVC said:

Put the Reshade d3d9.dll in the RTBP folder

Reshade don't work. It launches, and that's all. It does not detect its own shaders and presets, so it is completely useless.

[Sineadtanibata76]

Thank you so much for this!! More realism!!?

[CPVC]

17 hours ago, Veoly said:

Reshade don't work. It launches, and that's all. It does not detect its own shaders and presets, so it is completely useless.

Thanks for the heads up. It might work if you copied all the other Reshade files into the RTBP folder. I'll work on a better solution.

[SpaceMale]

Hi! This has a lot of potential!

I found a weird glitch with the animated textures. Depends on where the camera is. Without this installed its all ok.

Spoiler

[CPVC]

17 hours ago, SpaceMale said:

Hi! This has a lot of potential!

I found a weird glitch with the animated textures. Depends on where the camera is. Without this installed its all ok.

  Hide contents

Thank you for the bug report. Those are very appreciated.

 

So, I've discovered that the buggiest parts of my mod seem to all be related to butt physics. Would some of you mind testing this without butt physics enabled? Just set the "enableButtPhysics" setting in the "Settings.ini" file to "false" and tell me if you see any bugs. Thanks.

[nobodysfool]

Do I have to type anything in the game when I start to play to make it work? It worked in CAS when I was creating a sim but it didn't work during gameplay.

Is it neccessary to put source folder into Bin folder?

Is the breast bounce bigger when kspring is higher or lower than 150?

 

 

[Kodenu]

10 hours ago, nobodysfool said:

Do I have to type anything in the game when I start to play to make it work? It worked in CAS when I was creating a sim but it didn't work during gameplay.

Is it neccessary to put source folder into Bin folder?

Is the breast bounce bigger when kspring is higher or lower than 150?

 

 

Both d3d9.dll and RTBP folder go in to the bin folder. Nothing needs to be typed in for this to work. This is based on spring physic's. From what I can determine the breast is front to back motion and the butt is side to side motion. The walk style of the Sim does play in to this.

 

I am no expert on this but this is what I believe the numbers mean.

 

mass = weight or how heavy the object is.

damping = how much friction or resistance there is.

springK = I think this is a combination of certain spring physic's. Force and motion?

maxLength = the maximum directional travel of the spring.

 

Unfortunately, it isn't as simple as just one setting that creates more or less bounce. It is a combination of all the settings. You will have to mess with these settings for a bit to get what you want.  CPVC might be able to explain it better.

[Kodenu]

17 hours ago, CPVC said:

Thank you for the bug report. Those are very appreciated.

 

So, I've discovered that the buggiest parts of my mod seem to all be related to butt physics. Would some of you mind testing this without butt physics enabled? Just set the "enableButtPhysics" setting in the "Settings.ini" file to "false" and tell me if you see any bugs. Thanks.

I did this for a short time with both false and true. Set to false I did not notice any strange behavior. When I set it back to true, I did get some strange behavior in the body.