Good to hear that, Wing. A couple of things:
* I think this would make for a nice Chrono demo. Would you mind if I include it in the Chrono distribution and make it available to everyone? * Ubuntu 20.04 is indeed a bit old. I had no issues with VSG on 22.04 and 24.04. But we’re interested in knowing what prevents using Chrono::VSG on an older OS. Could you please provide some details on what problems you are encountering? Are you using an appropriate version of Vulkan? Are you using the buildVSG.sh script we provide with Chrono (see https://api.projectchrono.org/module_vsg_installation.html)? --Radu From: [email protected] <[email protected]> On Behalf Of kuwt Sent: Monday, January 12, 2026 11:26 AM To: ProjectChrono <[email protected]> Subject: Re: [chrono] Re: Simulation of spinning top collision Hello Radu, Thank you very much for your help. With the latest Chrono and the use of SetFrameRefToAbs, I manage to do a proper simulation (good.mp4). I am still using Irrlicht for the visualization since i am using an older version of ubuntu (20.04) and I encountered some problems installing Chrono::VSG. Wing On Friday, 9 January 2026 at 14:56:59 UTC+1 Radu Serban wrote: This is a cute simulation. >From the code you provided, I take it that you are using an older version of >Chrono. I just tried your code with the latest Chrono from the main git >branch, and I cannot reproduce the issue. Regarding your question about ChBodyEasMesh, note that this creates under the hood a ChBodyAuxRef (and not a ChBody). In that case, you probably want to control the pose of the reference frame with respect to the global frame. However, SetPos and SetRot actually affect the pose of the centroidal frame (relative to the global frame). I know that this is *very* confusing and it’s something I intend to change throughout Chrono whenever I will find the time. In the meantime, I suggest you * Use the latest code in the Chrono main branch * Switch to using Chrono::VSG for run-time visualization (better than Irrlicht) I attached a modification of your code where I * Changed the way the initial body poses are set * Used Chrono::VSG for run-time visualization * Flipped one of the spinning tops * Increased the initial angular velocities to 50 rad/s Let me know what you get. Radu From: [email protected] <[email protected]> On Behalf Of kuwt Sent: Friday, January 9, 2026 2:43 PM To: ProjectChrono <[email protected]> Subject: [chrono] Re: Simulation of spinning top collision Interestingly if I change the object from mesh to simple ChBodyEasyBox(as shown below). The weird attraction disappears(video a.mp4). I am not sure if I misunderstand anything for ChBodyEasyMesh. Forgot to mention that i'm using version release 9.0. // auto falling = chrono_types::make_shared<ChBodyEasyMesh>("../resource/spinningTop1.obj",7000,true,true,true,contact_mat,0.005); auto falling = chrono_types::make_shared<ChBodyEasyBox>(2,2,2,7000,true,true,contact_mat); falling->SetRot(QuatFromAngleY(180 * CH_DEG_TO_RAD)); falling->SetPos(ChVector3d(3, 0, 0)); falling->SetAngVelLocal(ChVector3d(0,0, 5)); sys.Add(falling); // auto falling2 = chrono_types::make_shared<ChBodyEasyMesh>( "../resource/spinningTop2.obj",7000,true,true,true,contact_mat,0.005); auto falling2 = chrono_types::make_shared<ChBodyEasyBox>(2,2,2,7000,true,true,contact_mat); falling2->SetRot(QuatFromAngleY(180 * CH_DEG_TO_RAD)); falling2->SetPos(ChVector3d(-3, 0, 0)); falling2->SetAngVelLocal(ChVector3d(0,0, 5)); sys.Add(falling2); On Thursday, 8 January 2026 at 15:05:36 UTC+1 kuwt wrote: Hello project chrono community, I want to simulate the collision of two spinning top using project chrono. However, I encounter a weird problem that the two spinning top goes towards each other. v0.mp4 is a video showing how they go towards each other.. v1.mp4 is a video showing another viewing angle. I release the two spinning top mid air with some angular velocity and let them drop to the floor. I expect they will go towards each other after they hit the floor but not during initially mid air. I inserted the object as shown in the following code script(whole minimal script attached as spinningtop2.cpp. The resources are attached too. I made the floor myself. The spinning tops are from github as mentioned in the code.): auto falling = chrono_types::make_shared<ChBodyEasyMesh>( "../resource/spinningTop1.obj",7000,true,true,true,contact_mat,0.005); falling->SetRot(QuatFromAngleY(180 * CH_DEG_TO_RAD)); falling->SetPos(ChVector3d(3, 0, 0)); falling->SetAngVelLocal(ChVector3d(0,0, 5)); sys.Add(falling); auto falling2 = chrono_types::make_shared<ChBodyEasyMesh>( "../resource/spinningTop2.obj",7000,true,true,true,contact_mat,0.005); falling2->SetRot(QuatFromAngleY(180 * CH_DEG_TO_RAD)); falling2->SetPos(ChVector3d(-3, 0, 0)); falling2->SetAngVelLocal(ChVector3d(0,0, 5)); sys.Add(falling2); auto floor = chrono_types::make_shared<ChBodyEasyMesh>( "../resource/floor.obj",7000,true,true,true,contact_mat,0.005); floor->SetPos(ChVector3d(0, 0, -3)); floor->SetFixed(true); sys.Add(floor); Does anybody know what I have misunderstood? Thank you. -- You received this message because you are subscribed to the Google Groups "ProjectChrono" group. 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