API Reference — `dna/layers/GeometryWriter`

`class GeometryWriter : public virtual DefinitionWriter`

Write geometry data (meshes, vertex positions, normals, texture coordinates, and layouts) into a rig DNA structure.

When to use this

Use this interface when you need to populate or replace the mesh geometry layer of a DNA asset during a write pass. Pair with GeometryReader to read geometry back after writing, or combine multiple set* calls to progressively build up mesh data before committing.

Method groups

Group	Methods
Mesh management	`clearMeshes`, `deleteMesh`
Vertex positions	`setVertexPositions`
Texture coordinates	`setVertexTextureCoordinates`
Vertex normals	`setVertexNormals`
Vertex layouts	`setVertexLayouts`

Example

// Obtain a Writer (which also implements GeometryWriter) via factory
dna::Writer* writer = dna::Writer::create(stream, memRes);

// Set vertex positions for mesh 0
std::vector<dna::Position> positions = { {0.0f, 1.0f, 0.0f}, {1.0f, 0.0f, 0.0f} };
writer->setVertexPositions(0, positions.data(), static_cast<std::uint32_t>(positions.size()));

// Set normals for mesh 0
std::vector<dna::Normal> normals = { {0.0f, 0.0f, 1.0f}, {0.0f, 0.0f, 1.0f} };
writer->setVertexNormals(0, normals.data(), static_cast<std::uint32_t>(normals.size()));

// Set texture coordinates for mesh 0
std::vector<dna::TextureCoordinate> uvs = { {0.5f, 0.5f}, {1.0f, 0.0f} };
writer->setVertexTextureCoordinates(0, uvs.data(), static_cast<std::uint32_t>(uvs.size()));

// Remove a mesh no longer needed
writer->deleteMesh(2);

Parameters

Name	Type	Description
`meshIndex`	`std::uint16_t`	required — zero-indexed position of the target mesh. Must be less than `getMeshCount` for `deleteMesh`; implicitly resizes storage for `set*` methods.
`positions`	`const Position*`	required — source buffer of `Position` values to copy into the mesh.
`textureCoordinates`	`const TextureCoordinate*`	required — source buffer of `TextureCoordinate` values to copy into the mesh.
`normals`	`const Normal*`	required — source buffer of `Normal` values to copy into the mesh.
`layouts`	`const VertexLayout*`	required — source buffer of `VertexLayout` values to copy into the mesh.
`count`	`std::uint32_t`	required — number of elements to copy from the corresponding source buffer.

Constraints

meshIndex passed to deleteMesh must be less than the value returned by getMeshCount.
For all set* methods, mesh storage is implicitly resized to accommodate the inferred mesh count from meshIndex — no explicit pre-allocation required.

Watch out for

Do not inherit directly from GeometryWriter. Implementors must inherit from Writer itself; this interface is a write-layer mixin only.

API Reference — dna/layers/GeometryWriter

class GeometryWriter : public virtual DefinitionWriter