wip Real-Time Body Physics (DirectX 11)

[FutaLover25]

1 hour ago, CPVC said:

 

Sorry, it needs to be the root of the installation directory, not the "Game\Bin\" directory. The location the Sims 4 was installed.

still crashing when Alt+tab, maybe something wrong with window mode

[CPVC]

13 minutes ago, FutaLover25 said:

still crashing when Alt+tab, maybe something wrong with window mode

 

Yeah, try borderless windowed. And please submit error reports if you encounter any other crashes. I'm hoping this new error reporting system can help me get to the bottom of issues like this.

[CPVC]

Thanks for checking out the experimental build and sending in your error reports, everyone. Looks like we've made some progress, but another, very similar issue has appeared. I think we might be dealing with a compiler bug here, but I'm not certain. I've put together another build that might move us forward or I could be barking up the wrong tree.

 

Anyway, give it a shot if you're up for it. In the mean time, I'm going to look into alternative compilers or maybe upgrading to the latest version of the compiler we're using in the hopes that they've fixed the bug if it exists. Thanks for your help.

 

RTBP 2.1-p1-e2 2026-03-26.zip

 

Edit: Oh, I should mention that I'm making a new installer in the new lightweight GUI toolkit I made the Companion in. This one will ship with all non-experimental releases, so no more having to download the installer separately. This ought to greatly simplify things for everyone.

 

Edited March 26 by CPVC
Installer

[Jazroy]

 

 

Hello, so I got this.

 

Log.txt

[CPVC]

17 hours ago, Jazroy said:

 

 

Hello, so I got this.

 

Log.txt 7.62 kB · 1 download

 

No need to post your logs here anymore. You can just click "Send" to send your log to me.

 

You are suffering from another common error that a lot of users that have submitted error reports have. I'm going to be putting out experimental builds much more often, so hopefully with some testing and users being good about sending their error reports in, we'll get this sorted in time.

[0Spirit0]

Are you a time traveller? 😏

 

[CPVC]

4 hours ago, 0Spirit0 said:

Are you a time traveller? 😏

 

 

Ha, no. I'm using a Python script to put together packages and it might not be putting in the correct date for newly created folders for some reason. Could be a bug in Python's "zipfile" module.

[CPVC]

I didn't really spend much time implementing angular physics aside from some experiments and adding the variables for them. They're disabled by default and enabling them just causes the breasts to spin out of control, but today I've been working at seriously implementing them and I like what I see so far. This could be in RTBP very soon.

 

https://files.catbox.moe/5xwfip.webm
https://files.catbox.moe/ruflqh.webm
https://streamable.com/v2gonc
https://streamable.com/ro4fwd

 

Edit: Latest experimental build has the angular physics. Check it out and let me know what you think:

RTBP v2.1-p1-e4 2026-03-30.zip

Edited March 30 by CPVC
Add link to latest experimental build.

[alexlll]

I don't understand how to set this up; it doesn't respond to the sliders and there's no way to turn anything on or off. https://drive.google.com/file/d/1rumFMZrhpQb19TIzSDEdaByBdW8XOsj8/view?usp=drive_link

[CPVC]

Wow, this is looking great! I wish I had gotten angular physics figured out earlier:

 

https://streamable.com/0ukdjd

[gloriousyuri]

is this basically procedural replacement for bouncing boobs by tonic?

[CPVC]

1 hour ago, gloriousyuri said:

is this basically procedural replacement for bouncing boobs by tonic?

 

It's real-time physics simulations added to the Sims 4. The simulators respond to the sim's movements and add physics to body parts, like the breasts and butt. The kind of jiggle physics you find in other games.

[HpMpAp]

There is a problem with the mod, and is that the sims 4 folder in documents folder is only called "the sims 4" for english users. For example, in spanish it's called "los sims 4", but your mod can only read from "the sims 4". With the little I know about programing, I think that has a very easy fix, but if it doesn't, then it would be great if you said in the instructions that if the sims folder inside documents has a different name, you MUST create one called "the sims 4" and add there the RTBP folder.

[CPVC]

7 hours ago, HpMpAp said:

There is a problem with the mod, and is that the sims 4 folder in documents folder is only called "the sims 4" for english users. For example, in spanish it's called "los sims 4", but your mod can only read from "the sims 4". With the little I know about programing, I think that has a very easy fix, but if it doesn't, then it would be great if you said in the instructions that if the sims folder inside documents has a different name, you MUST create one called "the sims 4" and add there the RTBP folder.

 

Oh, I had no idea they had different folder names for different languages. I'll add that to the readme and maybe come up with some other way of determining the documents directory. Thanks for the heads up.

[RyuK_]

I just updated from the old DX9 version to the DX11 version and I am running into issues to make it work. I replaced the RTBP Mod folder in the mods folder with the new one, replaced the RTBP folder with the new one, placed D3D11.dll in the game folder. The mod appears to have been loaded correctly, with the watermark appearing and the F11 menu working, the log says a connection has been established but there are no physics in game. I even tried changing some of the simulation parameters so they work even when the game is paused or in different speeds. No dice. I also confirmed this is the DirectX 11 one, not the DirectX 9 one. The checkbox is disabled.

[CPVC]

1 hour ago, RyuK_ said:

I just updated from the old DX9 version to the DX11 version and I am running into issues to make it work. I replaced the RTBP Mod folder in the mods folder with the new one, replaced the RTBP folder with the new one, placed D3D11.dll in the game folder. The mod appears to have been loaded correctly, with the watermark appearing and the F11 menu working, the log says a connection has been established but there are no physics in game. I even tried changing some of the simulation parameters so they work even when the game is paused or in different speeds. No dice. I also confirmed this is the DirectX 11 one, not the DirectX 9 one. The checkbox is disabled.

 

Any of the tests work (GUI -> Misc. -> Linear Testing -> Test X/Y/Z)? Which version of RTBP are you running?

[RyuK_]

6 hours ago, CPVC said:

 

Any of the tests work (GUI -> Misc. -> Linear Testing -> Test X/Y/Z)? Which version of RTBP are you running?

 

I tried the Linear Testing and no, no change. I first tried the RTBP v2.1-p1 version, then the RTBP v2.1-p1-e4 to see if it had fixed anything but also no change. Also, I just tested the DX9 version again without changing any of the mod files, I just put the dx9 version dll back in and it does work.

Edited April 4 by RyuK_

[CPVC]

13 hours ago, RyuK_ said:

 

I tried the Linear Testing and no, no change. I first tried the RTBP v2.1-p1 version, then the RTBP v2.1-p1-e4 to see if it had fixed anything but also no change. Also, I just tested the DX9 version again without changing any of the mod files, I just put the dx9 version dll back in and it does work.

 

Hmmm, ok. Could you post your log from the DX11 version? There's got to be some reason why you're not seeing any movement.

[mabebico]

hi any chance to fix this issue:

1. Some of the custom CC clothing does not align with the physics the breast is not doing the physics instead the top clothing only.
2. Half butt messed up and need to do few slide but when back to switch from another clothing type back again.
3. And when sim running (On Jogging) it didn't jiggle i think because of the setting, so im still a bit confused with the GUI setting to get the best physics.

[RyuK_]

11 hours ago, CPVC said:

 

Hmmm, ok. Could you post your log from the DX11 version? There's got to be some reason why you're not seeing any movement.

 

I can. Here is my log

Log.txt

[Zasz]

Would it attract more players if you add "DX11 Update" to the title? I was waiting for this update for a long time and while browsing I saw this thread but didnt feel like looking at it because usually it was still at DX9. Then I got curious and the update was out for some time already.

[0Spirit0]

On 3/30/2026 at 2:01 AM, CPVC said:

 

 

Edit: Latest experimental build has the angular physics. Check it out and let me know what you think:

RTBP v2.1-p1-e4 2026-03-30.zip 6.64 MB · 6 downloads

This update works mostly fine, the butts keep stretching to floor, the big issue I find is with ww animations boobs get crunched inside the chest

[CPVC]

16 hours ago, mabebico said:

hi any chance to fix this issue:

1. Some of the custom CC clothing does not align with the physics the breast is not doing the physics instead the top clothing only.
2. Half butt messed up and need to do few slide but when back to switch from another clothing type back again.
3. And when sim running (On Jogging) it didn't jiggle i think because of the setting, so im still a bit confused with the GUI setting to get the best physics.

 

There's no guarantee that RTBP will work with custom content, unfortunately. For it to work, it has to line up fairly well with Maxis's meshes. The breasts have to be where you'd expect them and the skeleton has to resemble that of the normal meshes.

 

As for the butt issue, that's known. It's something I need to work on. When butt simulators are made, butt bones are created on the fly by modifying mesh data. If there isn't enough room in bones matrix array for another bone, the new bone might not have a matrix when the rendering happens and you get the messed up butt. I need to figure out how to trick the Sims into allocating enough room for new bones.

 

Jogging doesn't produce the best results. Try getting your sims to dance. That looks pretty good. Or sword fight. Try lowering the mass and damping and increasing the spring k for more dynamic results. Mass will make things more resistant to change, whether that be from a standstill or moving. Damping controls how quickly the physics slow to a stop. Higher values mean quicker, lower mean slower. Spring K controls the springiness of the spring physics. Higher means bouncier, lower means less bouncy.

 

https://streamable.com/3t430b

 

15 hours ago, Zasz said:

Would it attract more players if you add "DX11 Update" to the title? I was waiting for this update for a long time and while browsing I saw this thread but didnt feel like looking at it because usually it was still at DX9. Then I got curious and the update was out for some time already.

 

It just might. Maybe I'll do that, thanks.

 

10 hours ago, 0Spirit0 said:

This update works mostly fine, the butts keep stretching to floor, the big issue I find is with ww animations boobs get crunched inside the chest

 

You might be able to fix the breasts getting crunched by messing with the min Z variable. This build has the new angular physics I've been working on enabled. I'd suggest using just angular physics or just linear physics, not combining them. To see just the angular physics in action, disable linear physics in the GUI by checking the "disableLinearPhysics" debug flag.

 

https://streamable.com/v2gonc

[mabebico]

4 hours ago, CPVC said:

 

There's no guarantee that RTBP will work with custom content, unfortunately. For it to work, it has to line up fairly well with Maxis's meshes. The breasts have to be where you'd expect them and the skeleton has to resemble that of the normal meshes.

 

As for the butt issue, that's known. It's something I need to work on. When butt simulators are made, butt bones are created on the fly by modifying mesh data. If there isn't enough room in bones matrix array for another bone, the new bone might not have a matrix when the rendering happens and you get the messed up butt. I need to figure out how to trick the Sims into allocating enough room for new bones.

 

Jogging doesn't produce the best results. Try getting your sims to dance. That looks pretty good. Or sword fight. Try lowering the mass and damping and increasing the spring k for more dynamic results. Mass will make things more resistant to change, whether that be from a standstill or moving. Damping controls how quickly the physics slow to a stop. Higher values mean quicker, lower mean slower. Spring K controls the springiness of the spring physics. Higher means bouncier, lower means less bouncy.

 

https://streamable.com/3t430b

 

 

It just might. Maybe I'll do that, thanks.

 

 

You might be able to fix the breasts getting crunched by messing with the min Z variable. This build has the new angular physics I've been working on enabled. I'd suggest using just angular physics or just linear physics, not combining them. To see just the angular physics in action, disable linear physics in the GUI by checking the "disableLinearPhysics" debug flag.

 

https://streamable.com/v2gonc

thanks looks great for the sword fight, i'll keep following the butt issue i hope u manage to figure it out the trick soon. Good job btw.

[shadowssss]

 

i used the .exe to install it, and this keeps happening when i run the game