---
title: initializationValue
framework: modelio
role: symbol
role_heading: Instance Property
path: modelio/mdlvertexattribute/initializationvalue
---

# initializationValue

The default value for vertex data for this attribute.

## Declaration

```swift
var initializationValue: vector_float4 { get set }
```

## Discussion

Discussion When you set the vertexDescriptor property of a MDLMesh object, the mesh automatically formats its vertex buffers to match the new descriptor. If the vertex descriptor contains a vertex attribute that is not already present in the mesh, the mesh creates a new vertex buffer (or allocates space in an interleaved vertex buffer, if the vertex descriptor describes such) for the new attribute, and fills in per-vertex data for that attribute using this property’s value. Although this property’s type is vector_float4, Model I/O  uses only the components of the vector that match the vertex attribute’s format property. For example, if you set this property’s value to the vector {1, 2, 3, 4} on a vertex attribute whose format is MDLVertexFormat.float2, each vertex will be initialized with the value {1, 2}. The default initialization value is the vector {0, 0, 0, 1}.

## See Also

### Inspecting a Vertex Attribute

- [name](modelio/mdlvertexattribute/name.md)
- [format](modelio/mdlvertexattribute/format.md)
- [offset](modelio/mdlvertexattribute/offset.md)
- [bufferIndex](modelio/mdlvertexattribute/bufferindex.md)