Question

我正在用c＃开发一个游戏引擎，我正在使用BulletSharp进行物理攻击。除了立方体之外，它运行良好：

http://i.stack.imgur.com/EPfrw.png

（轴对齐边界框为透明红色，模型为白色）

休息时，他们边缘的立场。因为我是从Collada模型加载的，所以我创建了一个ConvexHullShape()并将数据添加为矢量云。虽然使用BoxShape()会更有效（并且正常工作），但我不能保证所有模型都是立方体。我无法弄清楚为什么它们停留在顶点而不是平坦的边缘上。我的ConvexHullShape实现是错误的还是我需要使用不同类型的形状（物理才能正常工作）？

public RigidBody AddDynamicGeometry(ColladaGeometry geometry, Matrix4 transform)
        {
            List<Vector3> points = new List<Vector3>();
            foreach (Triangle tri in geometry.triangles)
            {
                points.Add(tri.vertices[0]);
                points.Add(tri.vertices[1]);
                points.Add(tri.vertices[2]);
            }
            CollisionShape shape = new ConvexHullShape(points);



            shape.UserObject = geometry;

            collisionShapes.Add(shape);

            RigidBody body = CreateRigidBody(geometry.triangles.Count * 10, transform, shape);

            return body;
        }

        public RigidBody CreateRigidBody(float mass, Matrix4 startTransform, CollisionShape shape)
        {
            bool isDynamic = (mass != 0.0f);

            Vector3 localInertia = Vector3.Zero;
            if (isDynamic)
                shape.CalculateLocalInertia(mass, out localInertia);

            DefaultMotionState myMotionState = new DefaultMotionState(startTransform);

            RigidBodyConstructionInfo rbInfo = new RigidBodyConstructionInfo(mass, myMotionState, shape, localInertia);
            RigidBody body = new RigidBody(rbInfo);

            physics_world.AddRigidBody(body);

            return body;
        }

Answer 1

ConvexHullShape期望质心（COM）为（0,0,0），但立方体偏离中心，使其朝向角落倾斜。

您可以使用ConvexTriangleMeshShape.CalculatePrincipalAxisTransform找到正确的COM。然后你可以从每个顶点减去COM以使COM回到0.但是，创建一个具有多维数据集的本地中心的CompoundShape会更容易。

// Create a ConvexTriangleMeshShape from the points
const int indexStride = 3 * sizeof(int);
const int vertexStride = 12;
int vertexCount = points.Count;
int indexCount = vertexCount / 3;

TriangleIndexVertexArray vertexArray = new TriangleIndexVertexArray();
IndexedMesh mesh = new IndexedMesh();
mesh.Allocate(vertexCount, vertexStride, indexCount, indexStride);
Vector3Array vdata = mesh.Vertices;
IntArray idata = mesh.TriangleIndices;
for (int i = 0; i < vertexCount; i++)
{
    vdata[i] = points[i];
    idata[i] = i;
}
vertexArray.AddIndexedMesh(mesh);
ConvexTriangleMeshShape shape = new ConvexTriangleMeshShape(vertexArray, true);

// Calculate center of mass
Matrix center = Matrix.Identity;
Vector3 inertia;
float volume;
shape.CalculatePrincipalAxisTransform(ref center, out inertia, out volume);

// Create a CompoundShape with COM offset
CompoundShape compound = new CompoundShape();
compound.AddChildShape(Matrix.Invert(center), shape);

注意：ConvexTriangleMeshShape.CalculatePrincipalAxisTransform适用于SVN中继，但不适用于BulletSharp 2.82。很快就会发布bug修复。

Bullet物理凸面船体与立方体

1 个答案: