Does b3GpuNarrowPhase::registerConcaveMesh work in a physics simulation?

[Kobayashi-Takahiro]

Hello everyone,

I have a question about physics simulation using GPU.

First, I confirmed that the physics simulation works as expected by using b3GpuNarrowPhase::registerConvexHullShape with the physics engine. This is based on the implementation found in the demo scene (OpenCL > Box-Box).

Next, I attempted to register a concave shape using an arbitrary mesh with the physics engine as follows:

// GpuConvexScene.cpp
// Line: 229

int colIndex = -1;
if (gUseInstancedCollisionShapes)
{
  //colIndex = m_data->m_np->registerConvexHullShape(utilPtr);
  b3AlignedObjectArray<b3Vector3> b3verts;
  b3AlignedObjectArray<int> b3idxs;
  size_t vlen = sizeof(tetra_vertices) / sizeof(float);
  for (size_t i = 0; i < vlen; i+=3) b3verts.push_back(b3MakeVector3(tetra_vertices[i], tetra_vertices[i+1], tetra_vertices[i+2]));
  vlen = sizeof(tetra_indices) / sizeof(int);
  for (size_t i = 0; i < vlen; i+=3) b3idxs.push_back(tetra_indices[i]);
  float scale[3] = { 1.0f, 1.0f, 1.0f };
  colIndex = m_data->m_np->registerConcaveMesh(&b3verts, &b3idxs, scale);
  
}

When I executed this code, all objects passed through the ground and fell downward, without any physics simulation or collision occurring. Upon further inspection, it seems that collision pairs in the broad phase can be obtained.

Does the current version of Bullet (version: 3.25) support GPU-based simulation when shapes are registered using registerConcaveMesh?

Thank you for your assistance.