Thanks for the screenshots.
I have made a few tests with a similar scene.
Unnatural bounces at triangle edges can have several causes and here are a few things you can try:
Contact Welding
Bounces can be caused by bad normal vectors at triangle edges.
Enable contact welding for the mesh:
triangleShapeMesh.EnableContactWelding = true;
and make the welding more aggressive by setting the welding limit to 1. This is a static property of the TriangleMeshAlgorithm class:
TriangleMeshAlgorithm.WeldingLimit = 1f;
Contact welding improves the contact normal vectors at triangle edges.
Perfect sphere contacts
Normally, when a sphere touches another object, the contact normal vector points in the direction from the sphere center to the contact. When contact welding is used, the contact positions can be a bit off. - But small errors can cause visible bounces.
We can correct this with a custom contact filter:
public class MyContactFilter : IContactFilter
{
private ContactReducer _defaultContactFilter = new ContactReducer();
public void Filter(ContactSet contactSet)
{
// Call the default contact filter.
_defaultContactFilter.Filter(contactSet);
// Abort if there are no contacts in this contact set.
if (contactSet.Count == 0)
return;
// If this is a sphere vs. * contact set, then we correct the position of the
// contact point to make sure that the contact position is in line with the sphere center.
var sphere = contactSet.ObjectA.GeometricObject.Shape as SphereShape;
if (sphere != null)
{
float radius = sphere.Radius;
foreach(var contact in contactSet)
contact.Position = contactSet.ObjectA.GeometricObject.Pose.Position + contact.Normal * (radius - contact.PenetrationDepth / 2);
return;
}
sphere = contactSet.ObjectB.GeometricObject.Shape as SphereShape;
if (sphere != null)
{
float radius = sphere.Radius;
foreach (var contact in contactSet)
contact.Position = contactSet.ObjectB.GeometricObject.Pose.Position - contact.Normal * (radius - contact.PenetrationDepth / 2);
}
}
}
Set this filter with:
simulation.CollisionDomain.CollisionDetection.ContactFilter = new MyContactFilter();
When I use contact welding and this contact filter, I get a very smooth movement.
If this does not help, here are a few more things you can try:
Lower friction
Try to use a lower friction. If the friction is lower, the spheres can glide more smoothly over bumps.
Allowed Penetration Depth
Try to lower the allowed penetration depth. For example:
simulation.Settings.Constraints.AllowedPenetration = 0.001f;
If this parameter is high (which is not good in your case), then the sphere will sink more into the triangle surface. And when it rolls to a triangle edge, it will perceive the neighbor edge as a small upwards step.
Gravity
When the gravity is high, small bumps can have a higher impact. Try to use a lower gravity, for example:
simulation.ForceEffects.Add(new Gravity() { Acceleration = new Vector3F(0, -5, 0)});
Height field instead of triangle mesh
Try to use a height field instead of a triangle mesh - if your scenario allows to use a height field.
Distorted triangles
Your triangles are very distorted (one side is small relative to the other sides). Subdivide your mesh to create more regular triangles. Very long, distorted shapes will create high numerical errors in many collision detection and physics algorithms.
Hope this helps - if not, let us know.