Hi Josh, thanks for your reply.
"it doesn't work" means, the result is: The rigidbody character cannot be blocked by the mirrored version shape/rigidbody. In the hkVisualDebugger, I can only see the the mirrored shape's mesh wireframe without the solid shading. It may caused by reverted triangle winding.
What I have done is: 1. Create ahkpTransformShape to wrap the normal mopp shape( constructed from hkpExtendedShape and TriangleSubpart). 2. Set the hkpTransformShape's transform scale to {1, 1, -1}. 3. Construct a rigid body by using this hkpTransformShape. 4. Add this rigid body to my hkpWorld.

In the game, I used the rigidbody character controller to control characters in the game. Everything works fine with normal mopp shapes. For the mirrored model, my current solution is: duplicated the normal model's vertices and indices data, mirror vertices position, then create a new mopp shape from these mirrored vertices and indices.
Is it possible to create a mirrored mopp shape without duplicating vertices data?

Josh, thanks for your quick reply.
I construct a 4x4 float matrix from a mirrored model's translation, rotation and a scale = {1, 1, -1}, and set this float matrix to a hkTransform through hkTransform::set4x4ColumnMajor(const hkFloat32* p). Then use this hkTransform to construct a hkpTransformShape. I know the hkTransform::set4x4ColumnMajor wasn't supposed to be used in this way. I just want to try if a scale = {1, 1, -1} will be treat as a unnormal rotation, and can be handle corrected. There are some mistakes about my current solution in my last post.Actually my current solution is: 1. Used the normal model shape's vertices data to construct a new TrianglesSubpart by set its scale to {1, 1, -1} through its setScaling interface. 2. Add this TrianglesSubpart to a new hkpExtendedMeshShape. 3. Build a new hkpMoppCode for this hkpExtendedMeshShape. 4. Construct a new mopp shape by using the new hkpExtendedMeshShape and the new hkpMoppCode. It works. I can avoid duplicate vertices in this way, but cannot reuse the normal model shape's hkpMoppCode. Is it possible to reuse the mopp code just like what the MoppInstancingDemo does? And this solution can only works at TrianglesSubpart (use a hkQsTransform member to represent its tranform), it cannot works at ShapesSubpart (use a hkQuaternion and a hkVector4 to represent its tranfrom).But I think duplicate sub convex shapes is acceptable, since convexshapes may cost much less memory space than vertices data.

-Yao

Josh, many thanks for your detail answer! It's helpful. And I can imagine this requirement will cause a big modification on the raycasting and linearcasting implement. But I still want suggest the havok team don't totally overlooked this requirement, at least don't make the havok more difficult to implement it in the future. Some day havok may need implement it.
Maybe the mirror trick has not got enough attention at present, and it usually be used at simple games for mirrored levels. I think the situation may will change in the future. This trick can be used at morden big games in variant styles (not only for mirrored levels) to bring some new game play styles and experience for player.

-Yao