Adding Mesh to simulation

[Fax3D]

Hi,
Could you please show me how to add a mesh to the simulation?

Here my code snippet where i extract vertices from my model to create a mesh... and then i dont' know how to use this mesh to add a new "body" to the simulation...

`
physics.BufferPool.Take(_trianglesCount, out var _triangleBuffer);
for (int i = 0; i < _trianglesCount; i++)
{
ref Triangle t = ref _triangleBuffer[i];

  t.A.X = _vertices[_indices[i * 3 + 0]].Position.X;
  t.A.Y = _vertices[_indices[i * 3 + 0]].Position.Y;
  t.A.Z = _vertices[_indices[i * 3 + 0]].Position.Z;

  t.B.X = _vertices[_indices[i * 3 + 1]].Position.X;
  t.B.Y = _vertices[_indices[i * 3 + 1]].Position.Y;
  t.B.Z = _vertices[_indices[i * 3 + 1]].Position.Z;

  t.C.X = _vertices[_indices[i * 3 + 2]].Position.X;
  t.C.Y = _vertices[_indices[i * 3 + 2]].Position.Y;
  t.C.Z = _vertices[_indices[i * 3 + 2]].Position.Z;

}
var _mesh = new Mesh(_triangleBuffer.Slice(0, _trianglesCount), System.Numerics.Vector3.One, physics.BufferPool);
physics.Bodies.Add(?)
`

Thanks for your help!

[RossNordby]

A Mesh is a shape, like a Sphere or Box. You'll need to add it first:
var shapeIndex = Simulation.Shapes.Add(mesh);
Then, when creating a body, provide the shapeIndex to the CollidableDescription in the BodyDescription or StaticDescription.

So if creating a body:

Simulation.Bodies.Add(BodyDescription.CreateDynamic(
    new RigidPose(new Vector3(0, -15, 0), QuaternionEx.CreateFromAxisAngle(new Vector3(0, 1, 0), MathF.PI / 2)), 
    mesh.ComputeClosedInertia(1), 
    new CollidableDescription(Simulation.Shapes.Add(mesh)), 
    new BodyActivityDescription(0.01f)));

Or a static:

Simulation.Statics.Add(new StaticDescription(
    new Vector3(0, -15, 0), QuaternionEx.CreateFromAxisAngle(new Vector3(0, 1, 0), MathF.PI / 2),
    new CollidableDescription(Simulation.Shapes.Add(mesh))));

2.4 also has some convenience casts that can make the description of bodies shorter. For example, you can directly provide the shape's TypedIndex as a CollidableDescription and a float for the BodyActivityDescription:

Simulation.Bodies.Add(BodyDescription.CreateDynamic(
    new RigidPose(new Vector3(0, -15, 0), QuaternionEx.CreateFromAxisAngle(new Vector3(0, 1, 0), MathF.PI / 2)),
    mesh.ComputeClosedInertia(1), Simulation.Shapes.Add(mesh), 0.01f));

Simulation.Statics.Add(new StaticDescription(
    new Vector3(0, -15, 0), QuaternionEx.CreateFromAxisAngle(new Vector3(0, 1, 0), MathF.PI / 2), 
    Simulation.Shapes.Add(mesh)));

You can find more examples in the demos. The idea is that shapes can be shared across many bodies/statics.

Also, I generally recommend against using Mesh with dynamic bodies. See the bit about meshes in the performance tips. Approximating meshes with simpler shapes, especially for dynamics, is a big win.