wip Real-Time Body Physics (DirectX 11)

[yokozii]

On 10/21/2025 at 9:49 PM, CPVC said:

 

Ah, ok, I think I see what's going on. The version of RTBP you are using is v0.4-p8. I checked the old source code and the breast simulation method you you like had been removed in later versions. In this build I've added it back. Enable the debug flag "testAltBreastPhysics6" to use that method.

 

RTBP DX11 Preview 2025-10-21.zip 6.74 MB · 34 downloads

so I've tried to install the preview version. the issue i think is happening is when the commander is saying will not connect and needs a RTBP ZIP to install and connect RTPB to sims4 it is ONLY allowing you to pull files from the zip file on the download page..which is the v0.4-p9 with the DX9 stuff inside and i think it overrides the new RTBP DX11 10-21-2025 because it still pulls in the DX9 files from the zip. I got that it installed properly when using the installer but won't work and when I added the d3d11.dll and changed to reshade.dll because I use reshade it didn't work still. my issue now is trying to use RTBP and run the game without reshade. but even if i re-add the copy of d3d11.dll and remove the reshade.dll the game gives me an error and won't start saying missing files. unless I rename it  reshade.dll

..so i think the install is my issue because maybe i should try without reshade but idk?? I tried the both 10-21-2025* and 10-18-2025 DX11 with the *debug . 

I never had an issue with installing RTBP like this. am i missing something ? or what did i do wrong here

RTBP Installer Log.txt RTBP Mod Log.txt

[CPVC]

49 minutes ago, yokozii said:

so I've tried to install the preview version. the issue i think is happening is when the commander is saying will not connect and needs a RTBP ZIP to install and connect RTPB to sims4 it is ONLY allowing you to pull files from the zip file on the download page..which is the v0.4-p9 with the DX9 stuff inside and i think it overrides the new RTBP DX11 10-21-2025 because it still pulls in the DX9 files from the zip. I got that it installed properly when using the installer but won't work and when I added the d3d11.dll and changed to reshade.dll because I use reshade it didn't work still. my issue now is trying to use RTBP and run the game without reshade. but even if i re-add the copy of d3d11.dll and remove the reshade.dll the game gives me an error and won't start saying missing files. unless I rename it  reshade.dll

..so i think the install is my issue because maybe i should try without reshade but idk?? I tried the both 10-21-2025* and 10-18-2025 DX11 with the *debug . 

I never had an issue with installing RTBP like this. am i missing something ? or what did i do wrong here

RTBP Installer Log.txt 7.49 kB · 0 downloads RTBP Mod Log.txt 1.75 kB · 0 downloads

 

Sorry, I forgot to mention that the experimental DX11 DLL isn't meant to be used with the installer and it won't work with ReShade.

 

This will need to be manually installed. Copy "d3d11.dll" to your "...\Game\Bin\" folder, don't rename it to anything else, and run the game in DX11 mode. Launch "TS4_x64.exe" and make sure DX9 mode is disabled by unchecking the "DirectX 9" option in the settings under the "Graphics" section. You'll need to restart your game after this.

 

This experimental preview release isn't really ready for prime time, it's not feature complete and it is buggy. It's just what I have so far. It does work, but I recommend sticking with the DX9 version for now.

[jeno3]

Hi CPVC,

 

everything looks good to me so far with the Dx11 version, except for the problems you mentioned. I'm still having the issue that the breast physics doesn't work with all the implants, but I guess I'll have to live with that. I think it depends on how much you change the mesh. Could you show me the range of mesh size that the breast physics works with? Then I can make sure to stay within that range in the future. The breast physics doesn't work for seniors, do you know about that?

 

I'm attaching some Blender files for you. Maybe you can see something. The original mesh is always the same one I'm working from. It's interesting to see that with the old RTBP (DX9), number -2- worked, but now it doesn't. I'm still trying to accommodate user requests, but I just can't get number -1- to work with RTBP.

 

Oh, I can't attach Blender files here. I'll send them to you separately.

[jeno3]

2 minutes ago, jeno3 said:

Hi CPVC,

 

everything looks good to me so far with the Dx11 version, except for the problems you mentioned. I'm still having the issue that the breast physics doesn't work with all the implants, but I guess I'll have to live with that. I think it depends on how much you change the mesh. Could you show me the range of mesh size that the breast physics works with? Then I can make sure to stay within that range in the future. The breast physics doesn't work for seniors, do you know about that?

 

I'm attaching some Blender files for you. Maybe you can see something. The original mesh is always the same one I'm working from. It's interesting to see that with the old RTBP (DX9), number -2- worked, but now it doesn't. I'm still trying to accommodate user requests, but I just can't get number -1- to work with RTBP.

 

Oh, I can't attach Blender files here. I'll send them to you separately.

 

Blenderfiles_.rar

[RealSiViX]

7 hours ago, jeno3 said:

Hi CPVC,

 

everything looks good to me so far with the Dx11 version, except for the problems you mentioned. I'm still having the issue that the breast physics doesn't work with all the implants, but I guess I'll have to live with that. I think it depends on how much you change the mesh. Could you show me the range of mesh size that the breast physics works with? Then I can make sure to stay within that range in the future. The breast physics doesn't work for seniors, do you know about that?

 

I'm attaching some Blender files for you. Maybe you can see something. The original mesh is always the same one I'm working from. It's interesting to see that with the old RTBP (DX9), number -2- worked, but now it doesn't. I'm still trying to accommodate user requests, but I just can't get number -1- to work with RTBP.

 

Oh, I can't attach Blender files here. I'll send them to you separately.

I have had none of the problems you have mentioned. Breast physics has been working fine for me on all breasts, including large breasts and seniors...

 

Make sure you have installed RTBP v0.4-p9-e1, including the d3d9.dll and then install the new d3d11.dll, also make sure that you are actually running the dx11 version of the game.

[CPVC]

On 10/30/2025 at 1:44 AM, jeno3 said:

Hi CPVC,

 

everything looks good to me so far with the Dx11 version, except for the problems you mentioned. I'm still having the issue that the breast physics doesn't work with all the implants, but I guess I'll have to live with that. I think it depends on how much you change the mesh. Could you show me the range of mesh size that the breast physics works with? Then I can make sure to stay within that range in the future. The breast physics doesn't work for seniors, do you know about that?

 

I'm attaching some Blender files for you. Maybe you can see something. The original mesh is always the same one I'm working from. It's interesting to see that with the old RTBP (DX9), number -2- worked, but now it doesn't. I'm still trying to accommodate user requests, but I just can't get number -1- to work with RTBP.

 

Oh, I can't attach Blender files here. I'll send them to you separately.

 

Yup, I'm aware that elder sims don't work. Right now, RTBP only looks for adult male and female sims. It can differentiate between the two by looking for male and female features in the mesh. Female sims have breasts and butts that protrude further than male sims. Male sims have broader shoulders than female sims.

 

In the future, I'll add elder and teen sim detection and you'll be able to customize physics based on age. I think teens work fine because they line up well enough with adults. I'll have to examine the meshes to see what to look for when detecting teens.

 

The rays I'm using for breast detection originate from (0.023, 0.351, 1.0) and (-0.023, 0.351, 1.0) in direction (0.0, 0.0, -1.0) for the left and right breasts. This is in game space. Converted to Blender space, that's (-0.092, -4.0, 1.4) in direction (0.0, 1.0, 0.0). RTBP assumes that the bones with the most influence are the breast bones.

 

So, for RTBP to work, the mesh needs to be identifiable as female and the closest vertex on the triangle the ray intersects with has to have the breast bones as the most influential bones.

 

As for your second mesh working in the DX9 version of RTBP, I examined the old source code and I did tweak the ray origins slightly between that version and the DX11 version. It used to be (0.022, 0.35, 1.0) as the origin, now it's (0.023, 0.351, 1.0). That might have been enough to make your mesh not function with RTBP anymore.

 

I'll look into a better way of detecting breasts that accommodates more variation in breast positions. Right now things have to line up fairly well with the default meshes. I've already got a couple ideas.

 

Attached is an image of your first mesh and where the ray would intersect it.

 

 

Edit: Whoops, forgot to mention another thing RTBP does when creating breast bones. In the event that the two bones gathered from the initial ray casts against each breast are equal, it'll go with the first pair of bones that are not equal. For example, if both breasts are influenced by the spine bone and their respective breast bones, but the spine is the most influential for both, RTBP will go with the ones that are different, the left and right breast bones.

Edited October 31, 2025 by CPVC

[RealSiViX]

On 10/30/2025 at 3:48 AM, jeno3 said:

 

Blenderfiles_.rar 7.86 MB · 1 download

I owe you an apology, I thought the elder sims had working breast physics but after playing some today I can confirm they do not (which I see CVPC has already confirmed as well), sorry for the confusion.

[jeno3]

On 10/31/2025 at 8:34 AM, CPVC said:

 

Yup, I'm aware that elder sims don't work. Right now, RTBP only looks for adult male and female sims. It can differentiate between the two by looking for male and female features in the mesh. Female sims have breasts and butts that protrude further than male sims. Male sims have broader shoulders than female sims.

 

In the future, I'll add elder and teen sim detection and you'll be able to customize physics based on age. I think teens work fine because they line up well enough with adults. I'll have to examine the meshes to see what to look for when detecting teens.

 

The rays I'm using for breast detection originate from (0.023, 0.351, 1.0) and (-0.023, 0.351, 1.0) in direction (0.0, 0.0, -1.0) for the left and right breasts. This is in game space. Converted to Blender space, that's (-0.092, -4.0, 1.4) in direction (0.0, 1.0, 0.0). RTBP assumes that the bones with the most influence are the breast bones.

 

So, for RTBP to work, the mesh needs to be identifiable as female and the closest vertex on the triangle the ray intersects with has to have the breast bones as the most influential bones.

 

As for your second mesh working in the DX9 version of RTBP, I examined the old source code and I did tweak the ray origins slightly between that version and the DX11 version. It used to be (0.022, 0.35, 1.0) as the origin, now it's (0.023, 0.351, 1.0). That might have been enough to make your mesh not function with RTBP anymore.

 

I'll look into a better way of detecting breasts that accommodates more variation in breast positions. Right now things have to line up fairly well with the default meshes. I've already got a couple ideas.

 

Attached is an image of your first mesh and where the ray would intersect it.

 

 

Edit: Whoops, forgot to mention another thing RTBP does when creating breast bones. In the event that the two bones gathered from the initial ray casts against each breast are equal, it'll go with the first pair of bones that are not equal. For example, if both breasts are influenced by the spine bone and their respective breast bones, but the spine is the most influential for both, RTBP will go with the ones that are different, the left and right breast bones.

Thank you for your detailed explanation. I will try to take it into account, however, it severely limits me regarding some user requests. Perhaps you could expand the possibilities a bit more with more variations. Nevertheless, I thank you for your work and perseverance. I think I speak for many when I say that you have made many players happy with this, myself included. I try to achieve something similar with my own content. I also enjoy experimenting with Blender, and if it works and looks good in the game, I'm satisfied. Ultimately, all we want is to give the game more realism and a more natural, human appearance.

[jeno3]

On 10/31/2025 at 10:47 AM, RealSiViX said:

I owe you an apology, I thought the elder sims had working breast physics but after playing some today I can confirm they do not (which I see CVPC has already confirmed as well), sorry for the confusion.

The funny thing is, I accidentally designed a CC for breasts that bypasses this and allows RTBP to work on older women. It's an older CC, but I'll dig it out. I'll make the CC available here for anyone who wants to use it as a workaround until CPVC is ready.

[CPVC]

6 hours ago, jeno3 said:

Thank you for your detailed explanation. I will try to take it into account, however, it severely limits me regarding some user requests. Perhaps you could expand the possibilities a bit more with more variations. Nevertheless, I thank you for your work and perseverance. I think I speak for many when I say that you have made many players happy with this, myself included. I try to achieve something similar with my own content. I also enjoy experimenting with Blender, and if it works and looks good in the game, I'm satisfied. Ultimately, all we want is to give the game more realism and a more natural, human appearance.

 

Thanks for the kind words. I'll definitely work on coming up with something new. It's a delicate balance trying to reliably find the breasts and avoid any false positives, like bouncing shoulders or something. There has to be a better way to accommodate modders like yourself.

[RavenTwain]

Anyway to disable/edit male breast physics?

[CPVC]

7 hours ago, RavenTwain said:

Anyway to disable/edit male breast physics?

 

Male breast physics should be disabled by default. However, sometimes a mesh can be incorrectly classified as female and sometimes physics will be applied to it. This usually manifests as bouncing shoulders.

 

At this time, RTBP can only analyze the mesh geometrically. The actual gender of the sim in-game is irrelevant. If it finds what it thinks are breasts, it'll make them move. It does attempt to determine the sim's gender before applying any physics, though. So if RTBP thinks a mesh is male, it's not going to try to find breasts on it.

 

Butt physics on males can be disabled. In your settings file, find the line that says "enableMaleButtPhysics = true" and change the "true" to "false".

Edited November 3, 2025 by CPVC

[RavenTwain]

5 hours ago, CPVC said:

 

Male breast physics should be disabled by default. However, sometimes a mesh can be incorrectly classified as female and sometimes physics will be applied to it. This usually manifests as bouncing shoulders.

 

At this time, RTBP can only analyze the mesh geometrically. The actual gender of the sim in-game is irrelevant. If it finds what it thinks are breasts, it'll make them move. It does attempt to determine the sim's gender before applying any physics, though. So if RTBP thinks a mesh is male, it's not going to try to find breasts on it.

 

Butt physics on males can be disabled. In your settings file, find the line that says "enableMaleButtPhysics = true" and change the "true" to "false".

Anything i can do to sim to force/tell RTBP that its a male. And for male butts i have the smallest of jiggle. lol

[jeno3]

22 hours ago, CPVC said:

 

Thanks for the kind words. I'll definitely work on coming up with something new. It's a delicate balance trying to reliably find the breasts and avoid any false positives, like bouncing shoulders or something. There has to be a better way to accommodate modders like yourself.

I hope you find a way. Perhaps we're expecting too much. The possibilities are unfortunately very limited. I notice it again and again when creating the shapes. It's also a shame that you can't extend the mesh with a proper body preset. That's probably the problem, since your physics are based on the original sim, which defines the area. As soon as someone designs custom content that affects half of the edges of the original sim mesh, these unwanted effects will likely occur. I can only vaguely imagine how you're designing it, but I don't know your approach in detail. That's probably beyond my knowledge.

[RavenTwain]

"RTBP Commander isnt connected to RTBP" and everything in the app/gui program is greyed out and it tries to reconnect every few seconds but always fails. (This is all b4 the Nov 4, 2025 TS4 update)

[CPVC]

3 hours ago, RavenTwain said:

"RTBP Commander isnt connected to RTBP" and everything in the app/gui program is greyed out and it tries to reconnect every few seconds but always fails. (This is all b4 the Nov 4, 2025 TS4 update)

 

RTBP has to be installed correctly and the Sims 4 has to be running.

[RavenTwain]

It worked before, than (b4 the nov 4th TS4 update), it stopped working and had the issues i mentioned. Its also getting [WinError 10061] when 'trying to connect' and yes, i have tried to open b4 and after starting game to no success either way.

[CPVC]

1 hour ago, RavenTwain said:

It worked before, than (b4 the nov 4th TS4 update), it stopped working and had the issues i mentioned. Its also getting [WinError 10061] when 'trying to connect' and yes, i have tried to open b4 and after starting game to no success either way.

 

Hmmm... Are you seeing the RTBP logo in the upper left corner of the screen when starting the game? If you don't see it, you might want to try reinstalling. Also, the version of RTBP you find on the main page requires the game to be in DirectX 9 mode. To do that, find your installation directory and execute "...\Game\Bin\TS4_DX9_x64.exe" or enable DirectX 9 in the game options.

 

If you're using the experimental DirectX 11 build, your game needs to be in DirectX 11 mode. Execute "...\Game\Bin\TS4_x64.exe" and disable DirectX9 in the game options.

[RavenTwain]

yea i took it off DirectX9 for smoother gameplay, slightly better lighting, ext. lol. Ill turn it back to see if it fixes it. thnx

Switching it back to d9 should fix it, since i see logo now (again). thnx.

Edited November 6, 2025 by RavenTwain

[CPVC]

On 11/3/2025 at 11:46 AM, jeno3 said:

I hope you find a way. Perhaps we're expecting too much. The possibilities are unfortunately very limited. I notice it again and again when creating the shapes. It's also a shame that you can't extend the mesh with a proper body preset. That's probably the problem, since your physics are based on the original sim, which defines the area. As soon as someone designs custom content that affects half of the edges of the original sim mesh, these unwanted effects will likely occur. I can only vaguely imagine how you're designing it, but I don't know your approach in detail. That's probably beyond my knowledge.

 

Would you mind sharing your ".package" files with me? I'd like to test them out in game.

[RealSiViX]

On 11/5/2025 at 11:00 PM, RavenTwain said:

yea i took it off DirectX9 for smoother gameplay, slightly better lighting, ext. lol. Ill turn it back to see if it fixes it. thnx

Switching it back to d9 should fix it, since i see logo now (again). thnx.

 

If you want to use the dx11 version, make sure you install the RTBP v0.4-p9-e1 from the main mod page (it is at the bottom of that page), including the dx9 dll from that package, then drop the dx11 dll in your game's Bin folder (The Sims 4\Game\Bin)

 

Working perfectly for me so far on dx11 aside from the minor issue that sometimes occurs with butts that CVPC is currently working on.

[RavenTwain]

12 hours ago, RealSiViX said:

 

If you want to use the dx11 version, make sure you install the RTBP v0.4-p9-e1 from the main mod page (it is at the bottom of that page), including the dx9 dll from that package, then drop the dx11 dll in your game's Bin folder (The Sims 4\Game\Bin)

 

Working perfectly for me so far on dx11 aside from the minor issue that sometimes occurs with butts that CVPC is currently working on.

It doesnt come with a dx11 file

[BakunyuuWaifu]

1 hour ago, RavenTwain said:

It doesnt come with a dx11 file

I think they mean from this post:

 

On 10/17/2025 at 11:35 PM, CPVC said:

While I'm still hunting down that last little annoying bug, I'll let you guys play with what I have so far. This is extremely experimental and only meant for people that know what they're doing. Test this at your own risk, backup your saves, etc., etc., etc. Don't be surprised if something unusual happens.

 

In this ZIP file, you'll find a "d3d11.dll" file. Put that in your "...\Game\Bin\" folder and execute "TS4_x64.exe" to start the DX11 version of the game.

 

Breasts appear to work flawlessly, but the butt causes some visual glitches. This is the bug I've been trying to squash. Oh, and for some outfits one of the butt cheeks is deflated. Another thing I need to fix. Ball physics are completely disabled. Those need some work.

 

RTBP Commander will work with this build, but some of the commands have not been implemented yet. Adjusting the variables will work, though.

 

Once I've taken care of the bug, I'll start adding everything back and put out an official release. After that, the DX9 version will be depreciated and all new work will go towards the DX11 version.

 

RTBP DX11 Preview 2025-10-18.zip 6.69 MB · 66 downloads

 

So like use the d3d9.dll from RTBP v0.4-p9-e1 and use the d3d11.dll from the post I quoted.

[RealSiViX]

13 hours ago, BakunyuuWaifu said:

I think they mean from this post:

 

 

So like use the d3d9.dll from RTBP v0.4-p9-e1 and use the d3d11.dll from the post I quoted.

 

Correct. Sorry, I should have been more clear...

[APassingGhost]

The mod doesn't seem to work with the EVE Body mod, as I've tested. Not really a "bug", just a compatibility thing I thought was worth mentioning.