add_grid()

bool MayaFlux::IO::Detail::VDBArchive::add_grid	(	const Kinesis::Lattice3D &	lattice,
		const VDBGridSpec &	spec
	)

Build one grid from active cells and retain it for saving.

The lattice becomes a per-axis scale-translate transform mapping index to world as cell_size() times index plus bounds.min plus half a cell, which reproduces Lattice3D::cell_center exactly.

Returns

False if the spec is inconsistent or the tree build failed. Call last_error() for detail. A failure leaves previously added grids intact.

Definition at line 541 of file VDBArchive.cpp.

{
    const size_t width = element_width(spec.is_vector);
    if (spec.values.size() != spec.coords.size() * width) {
        m_last_error = "grid '" + std::string(spec.name)
            + "': value bytes do not match coordinate count";
        return false;
    }
    if (spec.background.size() != width) {
        m_last_error = "grid '" + std::string(spec.name)
            + "': background is the wrong width";
        return false;
    }
 
    static_assert(sizeof(glm::ivec3) == sizeof(tvdb_vec3i),
        "glm::ivec3 and tvdb_vec3i must be layout compatible for the "
        "coordinate span to be passed through without a copy");
 
    auto& type_token = m_state->type_tokens.emplace_back();
    tvdb_grid_t tmpl = make_template(lattice, spec.is_vector, type_token.data());
 
    const std::string name(spec.name);
 
    tvdb_grid_t grid;
    const bool ok = tvdb_grid_from_sparse_typed_using_template(
        &tmpl,
        reinterpret_cast<const tvdb_vec3i*>(spec.coords.data()),
        spec.values.data(),
        spec.coords.size(),
        spec.is_vector ? TVDB_VALUE_VEC3F : TVDB_VALUE_FLOAT,
        spec.background.data(),
        name.c_str(),
        &grid);
 
    if (!ok) {
        m_last_error = "grid '" + name + "': tree build failed";
        return false;
    }
 
    auto& list = m_state->entries.emplace_back();
    list.reserve(spec.metadata.size() + 1);
 
    auto add_entry = [&](std::string_view key, std::string_view value) {
        std::string& k = m_state->strings.emplace_back(key);
        std::string& t = m_state->strings.emplace_back("string");
        std::string& v = m_state->strings.emplace_back(value);
 
        tvdb_meta_entry_t entry;
        std::memset(&entry, 0, sizeof(entry));
        entry.name = k.data();
        entry.type_name = t.data();
        entry.value.type = TVDB_VALUE_STRING;
        entry.value.u.s.str = v.data();
        entry.value.u.s.len = v.size();
        list.push_back(entry);
    };
 
    // OpenVDB reads a grid's name from metadata, not from the archive's grid
    // descriptor. Without this entry vdb_print and every DCC show it unnamed.
    add_entry("name", spec.name);
 
    for (const auto& [key, value] : spec.metadata) {
        add_entry(key, value);
    }
 
    grid.metadata.entries = list.data();
    grid.metadata.count = list.size();
    grid.metadata.capacity = list.size();
    grid.metadata.alloc = nullptr;
 
    m_state->grids.push_back(grid);
    return true;
}

References MayaFlux::IO::Detail::VDBGridSpec::background, MayaFlux::IO::Detail::VDBGridSpec::coords, MayaFlux::IO::Detail::VDBGridSpec::is_vector, k, m_last_error, m_state, MayaFlux::IO::Detail::VDBGridSpec::metadata, name, MayaFlux::IO::Detail::VDBGridSpec::name, value, MayaFlux::IO::Detail::VDBGridSpec::values, and width.

Referenced by MayaFlux::IO::VDBWriter::write().

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