API Reference — dna/layers/Geometry

Delta

Semantic alias for Vector3 that marks a value as a blend-shape displacement rather than a position or direction.

Why this exists

Blend-shape deltas are relative offsets applied on top of a base-mesh position — they are not absolute locations, and they should not be treated as directions requiring normalization. Using Delta instead of Vector3 at API boundaries makes this distinction explicit, prevents accidental unit-normalization, and identifies which attribute arrays hold morph-target data versus base geometry.

Relationships

  • Position — parallel alias for Vector3; holds absolute vertex positions to which deltas are added
  • Normal — parallel alias for Vector3; holds surface normals

Normal

Semantic alias for Vector3 that marks a value as a surface normal direction rather than a position or displacement.

Why this exists

Surface normals must be interpreted as unit-length direction vectors — normalizing them incorrectly or treating them as positional data produces rendering artifacts. This alias documents that intent at the type level. Together with Position and Delta, it forms a set of three semantically distinct Vector3 aliases that give geometry attribute arrays unambiguous meaning without introducing runtime cost.

Relationships

  • Position — parallel alias for Vector3; used for vertex positions
  • Delta — parallel alias for Vector3; used for blend-shape displacements
  • VertexLayout — the normal field indexes into an array of Normal values

Position

Semantic alias for Vector3 that marks a value as a spatial position rather than a direction or displacement.

Why this exists

All three geometric attribute types — Position, Normal, and Delta — share the same underlying Vector3 representation, but carry different mathematical meanings. Using named aliases instead of raw Vector3 makes function signatures and struct fields self-documenting and prevents passing a surface normal where a vertex position is expected. Position specifically identifies an absolute point in 3D space, as opposed to Normal (unit direction) or Delta (relative displacement).

Relationships

  • Normal — parallel alias for Vector3; used for surface directions, not positions
  • Delta — parallel alias for Vector3; used for blend-shape displacements
  • VertexLayout — the position field indexes into an array of Position values

TextureCoordinate

A UV pair that locates a point in 2D texture space for a mesh vertex.

Why this exists

Raw float pairs lack semantic meaning when stored alongside positions and normals. This struct names the two components u and v so code that reads or writes texture coordinates is self-documenting. It is consumed by VertexLayout, which stores an index into an array of TextureCoordinate values rather than embedding the UV directly in each vertex record.

Fields

Name Type Description
u float required — horizontal texture axis coordinate in [0, 1] normalized space
v float required — vertical texture axis coordinate in [0, 1] normalized space

Relationships

  • VertexLayout — holds a textureCoordinate index that references a slot in the TextureCoordinate attribute array
  • Position — parallel attribute type; combined with TextureCoordinate and Normal via VertexLayout
  • Normal — parallel attribute type used alongside this in the same vertex assembly

VertexLayout

Index triple that assembles a logical mesh vertex from three separate attribute arrays — position, texture coordinate, and normal.

Why this exists

DNA geometry stores positions, texture coordinates, and normals in separate indexed arrays rather than as an interleaved per-vertex record. This avoids duplicating shared attribute values across vertices that differ in only one component (common when UV seams split a shared position into multiple texture-space vertices). VertexLayout is the indirection record that names the three per-vertex indices, making explicit which slot in each attribute array contributes to a given logical vertex.

Fields

Name Type Description
position std::uint32_t required — zero-based index into the mesh's Position attribute array
textureCoordinate std::uint32_t required — zero-based index into the mesh's TextureCoordinate attribute array
normal std::uint32_t required — zero-based index into the mesh's Normal attribute array

Relationships

  • Position — attribute type indexed by the position field
  • TextureCoordinate — attribute type indexed by the textureCoordinate field
  • Normal — attribute type indexed by the normal field