C++ Assembly::object_instances方法代码示例

void InputBinder::build_assembly_symbol_table(
    const Assembly&                 assembly,
    SymbolTable&                    symbols)
{
    try
    {
        insert_entities(symbols, assembly.colors(), SymbolTable::SymbolColor);
        insert_entities(symbols, assembly.textures(), SymbolTable::SymbolTexture);
        insert_entities(symbols, assembly.texture_instances(), SymbolTable::SymbolTextureInstance);
        insert_entities(symbols, assembly.bsdfs(), SymbolTable::SymbolBSDF);
        insert_entities(symbols, assembly.bssrdfs(), SymbolTable::SymbolBSSRDF);
        insert_entities(symbols, assembly.edfs(), SymbolTable::SymbolEDF);
#ifdef APPLESEED_WITH_OSL
        insert_entities(symbols, assembly.shader_groups(), SymbolTable::SymbolShaderGroup);
#endif
        insert_entities(symbols, assembly.surface_shaders(), SymbolTable::SymbolSurfaceShader);
        insert_entities(symbols, assembly.materials(), SymbolTable::SymbolMaterial);
        insert_entities(symbols, assembly.lights(), SymbolTable::SymbolLight);
        insert_entities(symbols, assembly.objects(), SymbolTable::SymbolObject);
        insert_entities(symbols, assembly.object_instances(), SymbolTable::SymbolObjectInstance);
    }
    catch (const SymbolTable::ExceptionDuplicateSymbol& e)
    {
        RENDERER_LOG_ERROR("duplicate entity \"%s\".", e.string());
        ++m_error_count;
    }
}

AssemblyItem::AssemblyItem(
    Assembly&       assembly,
    BaseGroup&      parent,
    BaseGroupItem*  parent_item,
    ProjectBuilder& project_builder,
    ParamArray&     settings)
  : BaseGroupItem(g_class_uid, assembly, project_builder, settings)
  , m_assembly(assembly)
  , m_parent(parent)
  , m_parent_item(parent_item)
  , m_project_builder(project_builder)
{
    set_title(QString::fromAscii(assembly.get_name()));

    set_allow_edition(false);

    insertChild(
        3,
        m_bsdf_collection_item = add_multi_model_collection_item<BSDF>(assembly.bsdfs()));

    insertChild(
        4,
        m_edf_collection_item = add_multi_model_collection_item<EDF>(assembly.edfs()));

    insertChild(
        5,
        m_surface_shader_collection_item = add_multi_model_collection_item<SurfaceShader>(assembly.surface_shaders()));

    insertChild(
        6,
        m_material_collection_item = add_multi_model_collection_item<Material>(assembly.materials()));

    insertChild(
        7,
        m_light_collection_item = add_multi_model_collection_item<Light>(assembly.lights()));

    insertChild(
        8,
        m_object_collection_item =
            new ObjectCollectionItem(
                assembly.objects(),
                assembly,
                this,
                project_builder,
                settings));

    insertChild(
        9,
        m_object_instance_collection_item =
            new ObjectInstanceCollectionItem(
                new_guid(),
                EntityTraits<ObjectInstance>::get_human_readable_collection_type_name(),
                assembly,
                project_builder));
    m_object_instance_collection_item->add_items(assembly.object_instances());
}

    void collect_relations_from_assembly(Assembly& assembly)
    {
        collect_relations_from(assembly.colors());
        collect_relations_from(assembly.textures());
        collect_relations_from(assembly.texture_instances());
        collect_relations_from(assembly.shader_groups());
        collect_relations_from(assembly.assembly_instances());

        collect_relations_from(assembly.bsdfs());
        collect_relations_from(assembly.bssrdfs());
        collect_relations_from(assembly.edfs());
        collect_relations_from(assembly.surface_shaders());
        collect_relations_from(assembly.materials());
        collect_relations_from(assembly.lights());
        collect_relations_from(assembly.objects());
        collect_relations_from(assembly.object_instances());
        collect_relations_from(assembly.volumes());

        for (auto& child_assembly : assembly.assemblies())
            collect_relations_from_assembly(child_assembly);

        // Lights are implicitly referenced by their parent assembly.
        for (auto& light : assembly.lights())
        {
            const InputBinder::ReferencedEntity referenced_entity(assembly.lights(), &light);
            insert_relation(referenced_entity, assembly);
        }

        // Object instances are implicitly referenced by their parent assembly.
        for (auto& object_instance : assembly.object_instances())
        {
            const InputBinder::ReferencedEntity referenced_entity(assembly.object_instances(), &object_instance);
            insert_relation(referenced_entity, assembly);
        }

        // Assembly instances are implicitly referenced by their parent assembly.
        for (auto& assembly_instance : assembly.assembly_instances())
        {
            const InputBinder::ReferencedEntity referenced_entity(assembly.assembly_instances(), &assembly_instance);
            insert_relation(referenced_entity, assembly);
        }
    }

    void finalize_assembly(Assembly& assembly) override
    {
        // Insert the baked mesh object into the assembly.
        assembly.objects().insert(auto_release_ptr<Object>(m_mesh));

        // Instantiate the baked mesh object.
        assembly.object_instances().insert(
            ObjectInstanceFactory::create(
                "cubes_instance",
                ParamArray(),
                "cubes",
                Transformd::identity(),
                StringDictionary()
                    .insert("default", "cubes_material")));
    }

    void remove_unused_entities_from_assembly(Assembly& assembly)
    {
        remove_unused_entities_from(assembly.colors());
        remove_unused_entities_from(assembly.textures());
        remove_unused_entities_from(assembly.texture_instances());
        remove_unused_entities_from(assembly.shader_groups());
        remove_unused_entities_from(assembly.assembly_instances());

        remove_unused_entities_from(assembly.bsdfs());
        remove_unused_entities_from(assembly.bssrdfs());
        remove_unused_entities_from(assembly.edfs());
        remove_unused_entities_from(assembly.surface_shaders());
        remove_unused_entities_from(assembly.materials());
        remove_unused_entities_from(assembly.lights());
        remove_unused_entities_from(assembly.objects());
        remove_unused_entities_from(assembly.object_instances());
        remove_unused_entities_from(assembly.volumes());

        for (auto& child_assembly : assembly.assemblies())
            remove_unused_entities_from_assembly(child_assembly);
    }

void AssemblyTree::collect_regions(const Assembly& assembly, RegionInfoVector& regions) const
{
    assert(regions.empty());

    const ObjectInstanceContainer& object_instances = assembly.object_instances();
    const size_t object_instance_count = object_instances.size();

    // Collect all regions of all object instances of this assembly.
    for (size_t obj_inst_index = 0; obj_inst_index < object_instance_count; ++obj_inst_index)
    {
        // Retrieve the object instance and its transformation.
        const ObjectInstance* object_instance = object_instances.get_by_index(obj_inst_index);
        assert(object_instance);
        const Transformd& transform = object_instance->get_transform();

        // Retrieve the object.
        Object& object = object_instance->get_object();

        // Retrieve the region kit of the object.
        Access<RegionKit> region_kit(&object.get_region_kit());

        // Collect all regions of the object.
        for (size_t region_index = 0; region_index < region_kit->size(); ++region_index)
        {
            // Retrieve the region.
            const IRegion* region = (*region_kit)[region_index];

            // Compute the assembly space bounding box of the region.
            const GAABB3 region_bbox =
                transform.transform_to_parent(region->get_local_bbox());

            regions.push_back(
                RegionInfo(
                    obj_inst_index,
                    region_index,
                    region_bbox));
        }
    }
}

void LightSampler::collect_emitting_triangles(
    const Assembly&         assembly,
    const AssemblyInstance& assembly_instance)
{
    // Loop over the object instances of the assembly.
    const size_t object_instance_count = assembly.object_instances().size();
    for (size_t object_instance_index = 0; object_instance_index < object_instance_count; ++object_instance_index)
    {
        // Retrieve the object instance.
        const ObjectInstance* object_instance = assembly.object_instances().get_by_index(object_instance_index);

        // Retrieve the materials of the object instance.
        const MaterialArray& front_materials = object_instance->get_front_materials();
        const MaterialArray& back_materials = object_instance->get_back_materials();

        // Skip object instances without light-emitting materials.
        if (!has_emitting_materials(front_materials) && !has_emitting_materials(back_materials))
            continue;

        // Compute the object space to world space transformation.
        // todo: add support for moving light-emitters.
        const Transformd& object_instance_transform = object_instance->get_transform();
        const Transformd assembly_instance_transform =
            assembly_instance.transform_sequence().empty()
                ? Transformd::identity()
                : assembly_instance.transform_sequence().earliest_transform();
        const Transformd global_transform = assembly_instance_transform * object_instance_transform;

        // Retrieve the object.
        Object& object = object_instance->get_object();

        // Retrieve the region kit of the object.
        Access<RegionKit> region_kit(&object.get_region_kit());

        // Loop over the regions of the object.
        const size_t region_count = region_kit->size();
        for (size_t region_index = 0; region_index < region_count; ++region_index)
        {
            // Retrieve the region.
            const IRegion* region = (*region_kit)[region_index];

            // Retrieve the tessellation of the region.
            Access<StaticTriangleTess> tess(&region->get_static_triangle_tess());

            // Loop over the triangles of the region.
            const size_t triangle_count = tess->m_primitives.size();
            for (size_t triangle_index = 0; triangle_index < triangle_count; ++triangle_index)
            {
                // Fetch the triangle.
                const Triangle& triangle = tess->m_primitives[triangle_index];

                // Skip triangles without a material.
                if (triangle.m_pa == Triangle::None)
                    continue;

                // Fetch the materials assigned to this triangle.
                const size_t pa_index = static_cast<size_t>(triangle.m_pa);
                const Material* front_material =
                    pa_index < front_materials.size() ? front_materials[pa_index] : 0;
                const Material* back_material =
                    pa_index < back_materials.size() ? back_materials[pa_index] : 0;

                // Skip triangles that don't emit light.
                if ((front_material == 0 || front_material->get_uncached_edf() == 0) &&
                    (back_material == 0 || back_material->get_uncached_edf() == 0))
                    continue;

                // Retrieve object instance space vertices of the triangle.
                const GVector3& v0_os = tess->m_vertices[triangle.m_v0];
                const GVector3& v1_os = tess->m_vertices[triangle.m_v1];
                const GVector3& v2_os = tess->m_vertices[triangle.m_v2];

                // Transform triangle vertices to assembly space.
                const GVector3 v0_as = object_instance_transform.point_to_parent(v0_os);
                const GVector3 v1_as = object_instance_transform.point_to_parent(v1_os);
                const GVector3 v2_as = object_instance_transform.point_to_parent(v2_os);

                // Compute the support plane of the hit triangle in assembly space.
                const GTriangleType triangle_geometry(v0_as, v1_as, v2_as);
                TriangleSupportPlaneType triangle_support_plane;
                triangle_support_plane.initialize(TriangleType(triangle_geometry));

                // Transform triangle vertices to world space.
                const Vector3d v0(assembly_instance_transform.point_to_parent(v0_as));
                const Vector3d v1(assembly_instance_transform.point_to_parent(v1_as));
                const Vector3d v2(assembly_instance_transform.point_to_parent(v2_as));

                // Compute the geometric normal to the triangle and the area of the triangle.
                Vector3d geometric_normal = cross(v1 - v0, v2 - v0);
                const double geometric_normal_norm = norm(geometric_normal);
                if (geometric_normal_norm == 0.0)
                    continue;
                const double rcp_geometric_normal_norm = 1.0 / geometric_normal_norm;
                const double rcp_area = 2.0 * rcp_geometric_normal_norm;
                const double area = 0.5 * geometric_normal_norm;
                geometric_normal *= rcp_geometric_normal_norm;
                assert(is_normalized(geometric_normal));

                // Retrieve object instance space vertex normals.
                const GVector3& n0_os = tess->m_vertex_normals[triangle.m_n0];
//.........这里部分代码省略.........

bool InputBinder::try_bind_assembly_entity_to_input(
    const Scene&                    scene,
    const SymbolTable&              scene_symbols,
    const Assembly&                 assembly,
    const SymbolTable&              assembly_symbols,
    const char*                     entity_type,
    const char*                     entity_name,
    const char*                     param_value,
    InputArray::iterator&           input)
{
    if (input.format() == InputFormatEntity)
    {
        #define BIND(symbol, collection)                        \
            case symbol:                                        \
              input.bind(collection.get_by_name(param_value));  \
              return true

        switch (assembly_symbols.lookup(param_value))
        {
          BIND(SymbolTable::SymbolColor, assembly.colors());
          BIND(SymbolTable::SymbolTexture, assembly.textures());
          BIND(SymbolTable::SymbolTextureInstance, assembly.texture_instances());
          BIND(SymbolTable::SymbolBSDF, assembly.bsdfs());
          BIND(SymbolTable::SymbolBSSRDF, assembly.bssrdfs());
          BIND(SymbolTable::SymbolEDF, assembly.edfs());
#ifdef APPLESEED_WITH_OSL
          BIND(SymbolTable::SymbolShaderGroup, assembly.shader_groups());
#endif
          BIND(SymbolTable::SymbolSurfaceShader, assembly.surface_shaders());
          BIND(SymbolTable::SymbolMaterial, assembly.materials());
          BIND(SymbolTable::SymbolLight, assembly.lights());
          BIND(SymbolTable::SymbolObject, assembly.objects());
          BIND(SymbolTable::SymbolObjectInstance, assembly.object_instances());
        }

        #undef BIND
    }
    else
    {
        switch (assembly_symbols.lookup(param_value))
        {
          case SymbolTable::SymbolColor:
            bind_color_to_input(
                assembly.colors(),
                param_value,
                input);
            return true;

          case SymbolTable::SymbolTextureInstance:
            bind_texture_instance_to_input(
                assembly.texture_instances(),
                assembly.get_uid(),
                entity_type,
                entity_name,
                param_value,
                input);
            return true;
        }
    }

    return false;
}

//.........这里部分代码省略.........
            scene,
            scene_symbols,
            SymbolTable::symbol_name(SymbolTable::SymbolEDF),
            *i);
    }

#ifdef APPLESEED_WITH_OSL
    // Bind ShaderGroups inputs.
    for (each<ShaderGroupContainer> i = assembly.shader_groups(); i; ++i)
    {
        bind_assembly_entity_inputs(
            scene,
            scene_symbols,
            SymbolTable::symbol_name(SymbolTable::SymbolShaderGroup),
            *i);
    }
#endif

    // Bind surface shaders inputs.
    for (each<SurfaceShaderContainer> i = assembly.surface_shaders(); i; ++i)
    {
        bind_assembly_entity_inputs(
            scene,
            scene_symbols,
            SymbolTable::symbol_name(SymbolTable::SymbolSurfaceShader),
            *i);
    }

    // Bind materials inputs.
    for (each<MaterialContainer> i = assembly.materials(); i; ++i)
    {
        bind_assembly_entity_inputs(
            scene,
            scene_symbols,
            SymbolTable::symbol_name(SymbolTable::SymbolMaterial),
            *i);
    }

    // Bind lights inputs.
    for (each<LightContainer> i = assembly.lights(); i; ++i)
    {
        bind_assembly_entity_inputs(
            scene,
            scene_symbols,
            SymbolTable::symbol_name(SymbolTable::SymbolLight),
            *i);
    }

    // Bind objects inputs.
    for (each<ObjectContainer> i = assembly.objects(); i; ++i)
    {
        bind_assembly_entity_inputs(
            scene,
            scene_symbols,
            SymbolTable::symbol_name(SymbolTable::SymbolObject),
            *i);
    }

    // Bind objects to object instances. This must be done before binding materials.
    for (each<ObjectInstanceContainer> i = assembly.object_instances(); i; ++i)
    {
        i->unbind_object();

        for (AssemblyInfoIt j = m_assembly_info.rbegin(); j != m_assembly_info.rend(); ++j)
            i->bind_object(j->m_assembly->objects());

        i->check_object();
    }

    // Bind materials to object instances.
    for (each<ObjectInstanceContainer> i = assembly.object_instances(); i; ++i)
    {
        i->unbind_materials();

        for (AssemblyInfoIt j = m_assembly_info.rbegin(); j != m_assembly_info.rend(); ++j)
            i->bind_materials(j->m_assembly->materials());

        i->check_materials();
    }

    // Bind assemblies to assembly instances.
    for (each<AssemblyInstanceContainer> i = assembly.assembly_instances(); i; ++i)
    {
        i->unbind_assembly();

        for (AssemblyInfoIt j = m_assembly_info.rbegin(); j != m_assembly_info.rend(); ++j)
            i->bind_assembly(j->m_assembly->assemblies());

        i->bind_assembly(scene.assemblies());

        i->check_assembly();
    }

    // Recurse into child assemblies.
    for (const_each<AssemblyContainer> i = assembly.assemblies(); i; ++i)
        bind_assembly_entities_inputs(scene, scene_symbols, *i);

    // Pop the information about this assembly from the stack.
    m_assembly_info.pop_back();
}

void InputBinder::bind_assembly_entities_inputs(
    const Scene&                    scene,
    const SymbolTable&              scene_symbols,
    const Assembly&                 assembly,
    const SymbolTable&              assembly_symbols)
{
    // Bind BSDFs inputs.
    for (each<BSDFContainer> i = assembly.bsdfs(); i; ++i)
    {
        bind_assembly_entity_inputs(
            scene,
            scene_symbols,
            assembly,
            assembly_symbols,
            SymbolTable::symbol_name(SymbolTable::SymbolBSDF),
            i->get_name(),
            i->get_parameters(),
            i->get_inputs());
    }

    // Bind EDFs inputs.
    for (each<EDFContainer> i = assembly.edfs(); i; ++i)
    {
        bind_assembly_entity_inputs(
            scene,
            scene_symbols,
            assembly,
            assembly_symbols,
            SymbolTable::symbol_name(SymbolTable::SymbolEDF),
            i->get_name(),
            i->get_parameters(),
            i->get_inputs());
    }

    // Bind surface shaders inputs.
    for (each<SurfaceShaderContainer> i = assembly.surface_shaders(); i; ++i)
    {
        bind_assembly_entity_inputs(
            scene,
            scene_symbols,
            assembly,
            assembly_symbols,
            SymbolTable::symbol_name(SymbolTable::SymbolSurfaceShader),
            i->get_name(),
            i->get_parameters(),
            i->get_inputs());
    }

    // Bind materials inputs.
    for (each<MaterialContainer> i = assembly.materials(); i; ++i)
    {
        bind_assembly_entity_inputs(
            scene,
            scene_symbols,
            assembly,
            assembly_symbols,
            SymbolTable::symbol_name(SymbolTable::SymbolMaterial),
            i->get_name(),
            i->get_parameters(),
            i->get_inputs());

        i->bind_entities(
            assembly.surface_shaders(),
            assembly.bsdfs(),
            assembly.edfs());
    }

    // Bind lights inputs.
    for (each<LightContainer> i = assembly.lights(); i; ++i)
    {
        bind_assembly_entity_inputs(
            scene,
            scene_symbols,
            assembly,
            assembly_symbols,
            SymbolTable::symbol_name(SymbolTable::SymbolLight),
            i->get_name(),
            i->get_parameters(),
            i->get_inputs());
    }

    // Bind object instances inputs.
    for (each<ObjectInstanceContainer> i = assembly.object_instances(); i; ++i)
        i->bind_entities(assembly.materials());
}

AssemblyItem::AssemblyItem(
    EntityEditorContext&    editor_context,
    Assembly&               assembly,
    BaseGroup&              parent,
    BaseGroupItem*          parent_item)
  : BaseGroupItem(editor_context, g_class_uid, assembly)
  , m_assembly(assembly)
  , m_assembly_uid(assembly.get_uid())
  , m_parent(parent)
  , m_parent_item(parent_item)
{
    set_title(QString::fromAscii(assembly.get_name()));

    set_allow_edition(false);

    insertChild(
        3,
        m_bsdf_collection_item = add_multi_model_collection_item<BSDF>(assembly.bsdfs()));

    insertChild(
        4,
        m_bssrdf_collection_item = add_multi_model_collection_item<BSSRDF>(assembly.bssrdfs()));

    insertChild(
        5,
        m_edf_collection_item = add_multi_model_collection_item<EDF>(assembly.edfs()));

    insertChild(
        6,
        m_surface_shader_collection_item = add_multi_model_collection_item<SurfaceShader>(assembly.surface_shaders()));

    insertChild(
        7,
        m_material_collection_item = new MaterialCollectionItem(
            m_editor_context,
            assembly.materials(),
            assembly,
            this));

    insertChild(
        8,
        m_light_collection_item = add_multi_model_collection_item<Light>(assembly.lights()));

    insertChild(
        9,
        m_object_collection_item =
            new ObjectCollectionItem(
                m_editor_context,
                assembly.objects(),
                assembly,
                this));

    insertChild(
        10,
        m_object_instance_collection_item =
            new ObjectInstanceCollectionItem(
                m_editor_context,
                new_guid(),
                EntityTraits<ObjectInstance>::get_human_readable_collection_type_name(),
                assembly));
    m_object_instance_collection_item->add_items(assembly.object_instances());

    insertChild(
        11,
        m_volume_collection_item = add_multi_model_collection_item<Volume>(assembly.volumes()));

    m_editor_context.m_item_registry.insert(m_assembly, this);
}

void LightSampler::collect_emitting_triangles(
    const Assembly&                     assembly,
    const AssemblyInstance&             assembly_instance,
    const TransformSequence&            transform_sequence)
{
    // Loop over the object instances of the assembly.
    const size_t object_instance_count = assembly.object_instances().size();
    for (size_t object_instance_index = 0; object_instance_index < object_instance_count; ++object_instance_index)
    {
        // Retrieve the object instance.
        const ObjectInstance* object_instance = assembly.object_instances().get_by_index(object_instance_index);

        // Retrieve the materials of the object instance.
        const MaterialArray& front_materials = object_instance->get_front_materials();
        const MaterialArray& back_materials = object_instance->get_back_materials();

        // Skip object instances without light-emitting materials.
        if (!has_emitting_materials(front_materials) && !has_emitting_materials(back_materials))
            continue;

        double object_area = 0.0;

        // Compute the object space to world space transformation.
        // todo: add support for moving light-emitters.
        const Transformd& object_instance_transform = object_instance->get_transform();
        const Transformd& assembly_instance_transform = transform_sequence.get_earliest_transform();
        const Transformd global_transform = assembly_instance_transform * object_instance_transform;

        // Retrieve the object.
        Object& object = object_instance->get_object();

        // Retrieve the region kit of the object.
        Access<RegionKit> region_kit(&object.get_region_kit());

        // Loop over the regions of the object.
        const size_t region_count = region_kit->size();
        for (size_t region_index = 0; region_index < region_count; ++region_index)
        {
            // Retrieve the region.
            const IRegion* region = (*region_kit)[region_index];

            // Retrieve the tessellation of the region.
            Access<StaticTriangleTess> tess(&region->get_static_triangle_tess());

            // Loop over the triangles of the region.
            const size_t triangle_count = tess->m_primitives.size();
            for (size_t triangle_index = 0; triangle_index < triangle_count; ++triangle_index)
            {
                // Fetch the triangle.
                const Triangle& triangle = tess->m_primitives[triangle_index];

                // Skip triangles without a material.
                if (triangle.m_pa == Triangle::None)
                    continue;

                // Fetch the materials assigned to this triangle.
                const size_t pa_index = static_cast<size_t>(triangle.m_pa);
                const Material* front_material =
                    pa_index < front_materials.size() ? front_materials[pa_index] : 0;
                const Material* back_material =
                    pa_index < back_materials.size() ? back_materials[pa_index] : 0;

                // Skip triangles that don't emit light.
                if ((front_material == 0 || front_material->has_emission() == false) &&
                    (back_material == 0 || back_material->has_emission() == false))
                    continue;

                // Retrieve object instance space vertices of the triangle.
                const GVector3& v0_os = tess->m_vertices[triangle.m_v0];
                const GVector3& v1_os = tess->m_vertices[triangle.m_v1];
                const GVector3& v2_os = tess->m_vertices[triangle.m_v2];

                // Transform triangle vertices to assembly space.
                const GVector3 v0_as = object_instance_transform.point_to_parent(v0_os);
                const GVector3 v1_as = object_instance_transform.point_to_parent(v1_os);
                const GVector3 v2_as = object_instance_transform.point_to_parent(v2_os);

                // Compute the support plane of the hit triangle in assembly space.
                const GTriangleType triangle_geometry(v0_as, v1_as, v2_as);
                TriangleSupportPlaneType triangle_support_plane;
                triangle_support_plane.initialize(TriangleType(triangle_geometry));

                // Transform triangle vertices to world space.
                const Vector3d v0(assembly_instance_transform.point_to_parent(v0_as));
                const Vector3d v1(assembly_instance_transform.point_to_parent(v1_as));
                const Vector3d v2(assembly_instance_transform.point_to_parent(v2_as));

                // Compute the geometric normal to the triangle and the area of the triangle.
                Vector3d geometric_normal = cross(v1 - v0, v2 - v0);
                const double geometric_normal_norm = norm(geometric_normal);
                if (geometric_normal_norm == 0.0)
                    continue;
                const double rcp_geometric_normal_norm = 1.0 / geometric_normal_norm;
                const double rcp_area = 2.0 * rcp_geometric_normal_norm;
                const double area = 0.5 * geometric_normal_norm;
                geometric_normal *= rcp_geometric_normal_norm;
                assert(is_normalized(geometric_normal));

                // Retrieve object instance space vertex normals.
                Vector3d n0_os, n1_os, n2_os;
//.........这里部分代码省略.........