missed faces

[slava-jazz]

Hey, guys. I started using assimp in my project and got the problem. I am loading a FBX model from the https://sketchfab.com/3d-models/survival-guitar-backpack-799f8c4511f84fab8c3f12887f7e6b36 and getting this result:

As you see several faces are missed. Blender shows that model correct. Could some help me to understand what I am doing wrong?

To load I am using this call:

        Assimp::Importer importer;
        const aiScene* ai_scene = importer.ReadFile(_file_name,
            aiProcess_Triangulate |
            aiProcess_GenBoundingBoxes | 
            aiProcess_FlipUVs | 
            aiProcess_GenNormals |
            aiProcess_CalcTangentSpace |
            aiProcess_FixInfacingNormals |
            aiProcess_GenUVCoords 
        );

Then I read the vertices and take into account the transformation.

        for (unsigned int i = 0; i < _ai_mesh->mNumVertices; i++)
        {
            Stride stride;
            stride.position = _t* glm::vec4(a2g(_ai_mesh->mVertices[i]), 1);
            stride.normal = glm::normalize(_t * glm::vec4(a2g(_ai_mesh->mNormals[i]), 1));
            stride.tangent = glm::normalize(_t * glm::vec4(a2g(_ai_mesh->mTangents[i]), 1));
            stride.bitangent = glm::normalize(_t * glm::vec4(a2g(_ai_mesh->mBitangents[i]), 1));
            if (_ai_mesh->mTextureCoords[0])
            {
                stride.uv0 = a2g2d(_ai_mesh->mTextureCoords[0][i]);
            }
            mesh->addStride(stride);
        }

All this works fine.
Now about the problem. I am reading faces:

        for (unsigned int i = 0; i < _ai_mesh->mNumFaces; i++)
        {
            const aiFace& face = _ai_mesh->mFaces[i];
            const TriangleFace tf{ face.mIndices[0], face.mIndices[1], face.mIndices[2] };
            mesh->addFace(tf);
        }

where TriangleFace is defined as:

#pragma pack(push,1)
    struct TriangleFace
    {
        uint16_t indices[3];
    };
#pragma pack(pop)

I use very trivial fragment shader:

final_color = texture(basecolor_tex,vr.tex_coord) ;

and use static buffer:

    bool MeshPainter::loadStatic()
    {
        h[0] = h[1] = -1;
        glGenBuffers(2, h);
        if (h[0] != -1 && h[1] != -1)
        {
            glBindBuffer(GL_ARRAY_BUFFER, h[0]);
            glBufferData(GL_ARRAY_BUFFER, data->getStridesBufferSize(), data->getStridesBuffer(), GL_STATIC_DRAW);
            glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, h[1]);
            glBufferData(GL_ELEMENT_ARRAY_BUFFER, data->getIndecesBufferSize(), data->getIndiciesBuffer(), GL_STATIC_DRAW);
        }
        return h[0] != -1 && h[1] != -1;
   }

    void MeshPainter::draw()
    {
        glBindBuffer(GL_ARRAY_BUFFER, h[0]);
        glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, h[1]);
        size_t stride_size = sizeof(Stride);
        for (uint16_t index = 0; index < Stride::ATTRIBUTES_QTY; index++)
        {
            glVertexAttribPointer
            (
                index,
                Stride::getAttributeSize(index),
                GL_FLOAT,
                false,
                stride_size,
                Stride::getAttributeOffset(index)
            );
        }
        glDrawElements(GL_TRIANGLES, 3 * data->getFacesQty(), GL_UNSIGNED_SHORT, 0);
    }

[slava-jazz]

I switched to FBX SDK and found one issue in my code