as_mesh_access()

MAYAFLUX_API std::optional< MeshAccess > MayaFlux::Kakshya::as_mesh_access	(	const DataVariant &	vertex_variant,
		const DataVariant &	index_variant,
		const VertexLayout &	layout,
		std::optional< RegionGroup >	submeshes = std::nullopt
	)

Construct a MeshAccess from two DataVariant instances.

vertex_variant must hold vector<uint8_t> (canonical interleaved bytes). index_variant must hold vector<uint32_t>. layout must have stride_bytes > 0 and at least one attribute. submeshes is forwarded as-is; pass std::nullopt for single-mesh data.

Returns std::nullopt and logs an error for any type mismatch.

The RegionGroup convention: a single RegionGroup named "submeshes" holds one Region per submesh. Each Region carries coordinates [index_start, index_start + index_count) in the index dimension, with attributes "name", "material_name", and "vertex_offset". This mirrors the audio/video pattern where e.g. "transients" is the group and each onset event is a Region inside it.

Definition at line 29 of file MeshAccess.cpp.

{
    const auto* vbytes = std::get_if<std::vector<uint8_t>>(&vertex_variant);
    if (!vbytes || vbytes->empty()) {
        MF_ERROR(Journal::Component::Kakshya, Journal::Context::Runtime,
            "as_mesh_access: vertex_variant must hold a non-empty vector<uint8_t>");
        return std::nullopt;
    }
 
    const auto* ibuf = std::get_if<std::vector<uint32_t>>(&index_variant);
    if (!ibuf || ibuf->empty()) {
        MF_ERROR(Journal::Component::Kakshya, Journal::Context::Runtime,
            "as_mesh_access: index_variant must hold a non-empty vector<uint32_t>");
        return std::nullopt;
    }
 
    if (layout.stride_bytes == 0) {
        MF_ERROR(Journal::Component::Kakshya, Journal::Context::Runtime,
            "as_mesh_access: layout stride_bytes is zero");
        return std::nullopt;
    }
 
    if (layout.attributes.empty()) {
        MF_ERROR(Journal::Component::Kakshya, Journal::Context::Runtime,
            "as_mesh_access: layout has no attributes");
        return std::nullopt;
    }
 
    if (vbytes->size() % layout.stride_bytes != 0) {
        MF_ERROR(Journal::Component::Kakshya, Journal::Context::Runtime,
            "as_mesh_access: vertex byte count {} is not a multiple of stride {}",
            vbytes->size(), layout.stride_bytes);
        return std::nullopt;
    }
 
    MeshAccess ma;
    ma.vertex_ptr = vbytes->data();
    ma.vertex_bytes = vbytes->size();
    ma.index_ptr = ibuf->data();
    ma.index_count = static_cast<uint32_t>(ibuf->size());
    ma.layout = layout;
    ma.layout.vertex_count = static_cast<uint32_t>(vbytes->size() / layout.stride_bytes);
    ma.submeshes = std::move(submeshes);
    return ma;
}

References MayaFlux::Kakshya::VertexLayout::attributes, MayaFlux::Kakshya::MeshAccess::index_count, MayaFlux::Kakshya::MeshAccess::index_ptr, MayaFlux::Journal::Kakshya, MayaFlux::Kakshya::MeshAccess::layout, MF_ERROR, MayaFlux::Journal::Runtime, MayaFlux::Kakshya::VertexLayout::stride_bytes, MayaFlux::Kakshya::MeshAccess::submeshes, MayaFlux::Kakshya::MeshAccess::vertex_bytes, MayaFlux::Kakshya::VertexLayout::vertex_count, and MayaFlux::Kakshya::MeshAccess::vertex_ptr.

Referenced by MayaFlux::Kakshya::MeshData::access(), and MayaFlux::Kakshya::MeshInsertion::build().

Here is the caller graph for this function: