wip Real-Time Body Physics (DirectX 11)

[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

[ATIMKOS]

After instal this mod i can't run game.

[CPVC]

5 hours ago, shadowssss said:

 

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

 

Something is happening that is causing the game to crash. If you choose to send your log file in as an error report, I'll be able to take a look at it and possibly come up with a fix that will be included in the next version of RTBP.

 

You won't be able to play the game with RTBP as it is now, so use the installer to uninstall RTBP and try again after the next version comes out or try an experimental version that might already include the fix.

 

4 hours ago, ATIMKOS said:

After instal this mod i can't run game.

 

Like the other poster I responded to, send in an error report if you want. I might be able to produce a fix that will work in future versions. Maybe try an experimental version or uninstall for the time being.

[CPVC]

 

RTBP v2.2 has been released. This new version has the angular physics I've been showing off. They have replaced linear physics as the new default. You can go back to the old linear physics by disabling angular physics with the "disableAngularPhysics" debug flag and enabling linear physics with "enableLinearPhysics". It's also possible to use both at the same time.

 

Angular is the new default because I think it looks much more realistic and is more similar to the way jiggle physics are done in other games. Let me know what you think, though.

 

https://streamable.com/0ukdjd

 

Another big change is that the command server has been removed. You will no longer be able to use the RTBP Commander to tweak RTBP and should use the internal GUI instead. Just press "F11" in game to open the GUI. Remember that you can right click on a slider to configure its range or to split/join left and right body parts.

 

I am planning on making the internal GUI be able to pop out from the game and have a window of it's own, so those of you who have multiple monitors can have the game in one window and the GUI in the other.

 

Since I made a new lightweight installer that I package with every RTBP release and I've removed support for the Commander, the old GUI tools are now obsolete, so you won't be needing those anymore.

 

I've also implemented some potential fixes for some things I've seen in the log files all of you have sent me. For those of you who weren't able to get RTBP running before, it might work for you now. Thanks to the error reporting, I have a better idea of what I need to do for the next release to get RTBP working for all users. Once again, thanks for your help with that.

 

Some locales have a Sims 4 documents directory that has been translated to their native language. If your computer is set to Spanish, French, German, or Dutch, RTBP should recognize this and select the correct documents directory. The installer, too. I wasn't able to test this, so let me know if it doesn't work.

 

RTBP will no longer look for a "reshade.dll", "ReShade64.dll", etc. to try and load as it's DirectX DLL. ReShade is hooking another DLL now and there is no longer a conflict between RTBP and ReShade. Both can be used together out of the box with no extra configuration needed.

 

It was also brought to my attention that the installer didn't scale with the system font. I believe this is fixed now.

 

The read me has been updated to reflect the changes.

 

Internal GUI improvements.

 

Let me know if anything is broken and I'll get it fixed ASAP. Thanks.

 

Edit: Add this to the bottom of your "Settings.ini" file to go back to linear physics:

 

[rtbp.debugFlags]
disableAngularPhysics = true
enableLinearPhysics = true

 

Edit 2: To see effects similar to what you see in the video above, disable angular limits. Use the GUI to check the "disableAngularLimits" debug flag or add "disableAngularLimits = true" to your "Settings.ini" file under the "[rtbp.debugFlags]" section.

 

Edited April 9 by CPVC

[RyuK_]

21 hours ago, CPVC said:

 

RTBP v2.2 has been released. This new version has the angular physics I've been showing off. They have replaced linear physics as the new default. You can go back to the old linear physics by disabling angular physics with the "disableAngularPhysics" debug flag and enabling linear physics with "enableLinearPhysics". It's also possible to use both at the same time.

 

Angular is the new default because I think it looks much more realistic and is more similar to the way jiggle physics are done in other games. Let me know what you think, though.

 

https://streamable.com/0ukdjd

 

Another big change is that the command server has been removed. You will no longer be able to use the RTBP Commander to tweak RTBP and should use the internal GUI instead. Just press "F11" in game to open the GUI. Remember that you can right click on a slider to configure its range or to split/join left and right body parts.

 

I am planning on making the internal GUI be able to pop out from the game and have a window of it's own, so those of you who have multiple monitors can have the game in one window and the GUI in the other.

 

Since I made a new lightweight installer that I package with every RTBP release and I've removed support for the Commander, the old GUI tools are now obsolete, so you won't be needing those anymore.

 

I've also implemented some potential fixes for some things I've seen in the log files all of you have sent me. For those of you who weren't able to get RTBP running before, it might work for you now. Thanks to the error reporting, I have a better idea of what I need to do for the next release to get RTBP working for all users. Once again, thanks for your help with that.

 

Some locales have a Sims 4 documents directory that has been translated to their native language. If your computer is set to Spanish, French, German, or Dutch, RTBP should recognize this and select the correct documents directory. The installer, too. I wasn't able to test this, so let me know if it doesn't work.

 

RTBP will no longer look for a "reshade.dll", "ReShade64.dll", etc. to try and load as it's DirectX DLL. ReShade is hooking another DLL now and there is no longer a conflict between RTBP and ReShade. Both can be used together out of the box with no extra configuration needed.

 

It was also brought to my attention that the installer didn't scale with the system font. I believe this is fixed now.

 

The read me has been updated to reflect the changes.

 

Internal GUI improvements.

 

Let me know if anything is broken and I'll get it fixed ASAP. Thanks.

 

Edit: Add this to the bottom of your "Settings.ini" file to go back to linear physics:

 

[rtbp.debugFlags]
disableAngularPhysics = true
enableLinearPhysics = true

 

Edit 2: To see effects similar to what you see in the video above, disable angular limits. Use the GUI to check the "disableAngularLimits" debug flag or add "disableAngularLimits = true" to your "Settings.ini" file under the "[rtbp.debugFlags]" section.

 

I updated to the latest version but it appears the issue persists on my end. I've read through the log and it still says "No usable custom D3D11 DLL found. Using system DLL", which makes no sense. I ran the installer and it worked without issues. The DLL is in the correct place.

Log.txt

[CPVC]

1 hour ago, RyuK_ said:

I updated to the latest version but it appears the issue persists on my end. I've read through the log and it still says "No usable custom D3D11 DLL found. Using system DLL", which makes no sense. I ran the installer and it worked without issues. The DLL is in the correct place.

Log.txt 5.38 kB · 1 download

 

That's just the log message I forgot to remove. The code that actually looks for a non-system DLL has been removed, though. As for your issue, I have a theory. Give me a bit and I'll whip up a new DLL for you.

 

Edit: Ok, try this. It just might work:

 

RTBP v2.2~1 2026-04-10.zip

 

Edited April 10 by CPVC

[RyuK_]

41 minutes ago, CPVC said:

 

That's just the log message I forgot to remove. The code that actually looks for a non-system DLL has been removed, though. As for your issue, I have a theory. Give me a bit and I'll whip up a new DLL for you.

 

Edit: Ok, try this. It just might work:

 

RTBP v2.2~1 2026-04-10.zip 2.13 MB · 1 download

 

I don't know what I might be doing wrong. I tried this DLL, tried it on CAS, tried it on live mode, there are still no physics.

Log.txt

[CPVC]

16 minutes ago, RyuK_ said:

I don't know what I might be doing wrong. I tried this DLL, tried it on CAS, tried it on live mode, there are still no physics.

Log.txt 6.37 kB · 0 downloads

 

Alright, try this. It's not going to work, but it'll point me in the right direction, maybe. Add this to the bottom of your Settings.ini file:

 

[rtbp.debugFlags]
logPossibleInputLayouts = true

 

Try the new DLL with that change to your settings file and post the log file. Make sure a sim is loaded, so just go into Create A Sim. This might give me the information I need to proceed with a fix. Thanks!

[RyuK_]

7 minutes ago, CPVC said:

 

Alright, try this. It's not going to work, but it'll point me in the right direction, maybe. Add this to the bottom of your Settings.ini file:

 

 

[rtbp.debugFlags]
logPossibleInputLayouts = true

 

 

Try the new DLL with that change to your settings file and post the log file. Make sure a sim is loaded, so just go into Create A Sim. This might give me the information I need to proceed with a fix. Thanks!

Alright. I enabled the flag as you requested. Here is the log

Log.txt

[CPVC]

15 minutes ago, RyuK_ said:

Alright. I enabled the flag as you requested. Here is the log

Log.txt 37.02 kB · 0 downloads

 

Alright, I'll see what I can do with that info. Thanks for your help!

[alexlll]

Is it possible to make  work two versions, DirectX 9 and DirectX 11 together. One is responsible for breast physics and the second one, for example, for the physics of the ass.

Edited April 11 by alexlll

[CPVC]

On 4/10/2026 at 9:56 PM, alexlll said:

Is it possible to make  work two versions, DirectX 9 and DirectX 11 together. One is responsible for breast physics and the second one, for example, for the physics of the ass.

 

You mean having angular physics for the breasts and linear for the butt? No, not currently, but that is a good idea. I'll add that.

[RyuK_]

17 hours ago, CPVC said:

 

You mean having angular physics for the breasts and linear for the butt? No, not currently, but that is a good idea. I'll add that.

Since I am having trouble to run the DX11 version of the mod, I would like to see angular physics for the DX9 version too, if possible, since that one still works normally on my end.

[ATIMKOS]

How to change RTBP Commander 10k windows size? In my game it looks like this:

[CPVC]

On 4/13/2026 at 11:19 AM, ATIMKOS said:

How to change RTBP Commander 10k windows size? In my game it looks like this:

 

  Reveal hidden contents

 

 

 

 

 

 

It was supposed to scale with the window size, but I guess I didn't read the ImGui documentation close enough. I think I've got it now. I'll put out an experimental build later today with some other changes and link you to it when it's ready.

 

Edit: Here you go. This experimental version also enables selectively enabling/disabling linear/angular physics per-body part, so angular physics can be used for the breasts and linear for the butt if you desire. They can be split too, so you could have angular for the left breast, linear for the right. Why not?

 

RTBP v2.2~2 2026-04-14.zip

Edited April 15 by CPVC
Add experimental version.

[0Spirit0]

I found a glitch with one top. I'm sending that top and a small video showing the glitch. It only happens when zoomed out.

 

Recorded Videos.7z

[jeno3]

Hi CPVC, I have a question about the current version. The pack contains a D9 DLL; is that for DirectX 9 or 11? Or does it work for both, regardless of what I select in the game?

[jeno3]

...and would it be possible to change the area of effect downwards from the selected area? As soon as I change the level below, the shoulders in the game also sag.

[CPVC]

20 hours ago, 0Spirit0 said:

I found a glitch with one top. I'm sending that top and a small video showing the glitch. It only happens when zoomed out.

 

Recorded Videos.7z 12.78 MB · 1 download

 

That happens occasionally. Until I can find a fix, you might consider disabling butt physics if you can live without them. I'm pretty sure glitches like that are from creating new bones on the fly like butt physics does.

 

14 hours ago, jeno3 said:

Hi CPVC, I have a question about the current version. The pack contains a D9 DLL; is that for DirectX 9 or 11? Or does it work for both, regardless of what I select in the game?

 

No, if it contains a d3d9.dll, that's gotta be the legacy version. You want this one here:

 

https://www.loverslab.com/files/file/14085-real-time-body-physics-directx-11/?do=download&r=2147932&confirm=1&t=1&csrfKey=cb097b74a9e4d67eb44f0c494d6413e7

 

14 hours ago, jeno3 said:

...and would it be possible to change the area of effect downwards from the selected area? As soon as I change the level below, the shoulders in the game also sag.

 

I'll look into it. Maybe there's a way to reliably calculate a pivot position based on the center of the target bone, the vertices they affect and their weights. I'll do some experiments.

[alexlll]

On 4/12/2026 at 7:58 AM, CPVC said:

 

You mean having angular physics for the breasts and linear for the butt? No, not currently, but that is a good idea. I'll add that.

I have a DirectX 9 version that works well with breasts; it's already perfectly configured, and I wouldn't want to change it, but the buttock physics don't work. If I could run both DirectX 9 versions, I'd keep the old one, and DirectX 11 would handle the butt.