API Reference — dna/layers/Geometry

Delta

Type alias for Vector3 that represents a per-vertex offset.

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.

Delta labels a Vector3 as an offset rather than an absolute position. Like Position and Normal, it is only an alias, so the compiler treats them as the same type.

Construction

dna::Delta d = dna::Vector3{0.0f, 0.02f, 0.0f};

Relationships

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

Normal

Type alias for Vector3 that represents a vertex normal.

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.

Normal labels a Vector3 as a normal direction. The compiler does not enforce the distinction, since it is an alias of Vector3.

Construction

dna::Normal n = dna::Vector3{0.0f, 0.0f, 1.0f};

Relationships

  • Position — sibling alias of Vector3
  • Delta — sibling alias of Vector3
  • VertexLayout — holds an index into the normal array
  • Delta — parallel alias for Vector3; used for blend-shape displacements

Position

Type alias for Vector3 that represents a vertex 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).

Construction

dna::Position p = dna::Vector3{0.0f, 1.5f, 0.0f};

Relationships

  • Normal — sibling alias of Vector3
  • Delta — sibling alias of Vector3
  • VertexLayout — holds an index into the position array
  • Normal — parallel alias for Vector3; used for surface directions, not positions
  • Delta — parallel alias for Vector3; used for blend-shape displacements

TextureCoordinate

A 2D UV coordinate for a vertex.

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.

TextureCoordinate gives UV pairs a named type instead of two loose floats. It keeps u and v together, and keeps them distinct from the 3D Position, Normal and Delta types.

Fields

Name Type Description
u float required. Horizontal texture coordinate.
v float required. Vertical texture coordinate.

Construction

dna::TextureCoordinate uv{0.25f, 0.75f};

Relationships

  • VertexLayout — holds an index into the texture coordinate array
  • Normal — parallel attribute type used alongside this in the same vertex assembly
  • VertexLayout — holds a textureCoordinate index that references a slot in the TextureCoordinate attribute array

VertexLayout

Describes one vertex as a set of indices into the position, texture coordinate and normal arrays.

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.

VertexLayout stores indices instead of copies of the data. Vertices can then share positions, UVs and normals.

Fields

Name Type Description
position std::uint32_t required. Index into the vertex positions.
textureCoordinate std::uint32_t required. Index into the texture coordinates.
normal std::uint32_t required. Index into the vertex normals.

Construction

dna::VertexLayout layout{12u, 12u, 7u};

Relationships

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