9.8. The VertexBuffer Object

A VertexBuffer object is an optimal read-only container for vertex data.

9.8.1. Constructor

A VertexBuffer object can be constructed with GraphicsDevice.createVertexBuffer.

9.8.2. Methods

9.8.2.1. setData

Summary

Set the data by passing in an array of numbers.

Vertex data stored on the VertexBuffer, it consists of an array of numbers, one value for each component of every attribute of all vertices. The number of components per attribute depends on the attribute format.

Create the VertexBuffer as dynamic if you are planning to update the vertex data at runtime.

Changing or requesting the vertex data can be an expensive operation.

Syntax

// request all the data
var vertexData = [100.0, 200.0, 3, 1000,
                  200.0, 200.0, 4, 2000,
                  100.0, 100.0, 5, 3000,
                  200.0, 100.0, 6, 4000]

var offset = 0;
var count = vertexData.length / vertexBuffer.stride;
vertexBuffer.setData(vertexData, offset, count);

vertexData

An array of numbers in the same format as the data element passed in to createVertexBuffer.

offset (Optional)

Offset from the beginning of the buffer in verticies. Optional, assumed to be 0 if omitted.

count (Optional)

The number of verticies to write. Optional, assumed to be size of the buffer if omitted.

9.8.2.2. map

Summary

Requests write access to a region of the VertexBuffer.

Syntax

var writer = vertexBuffer.map(offset, count);
if (writer)
{
    for (var n = 0; n < count; n += 1)
    {
        // This VertexBuffer has 3 attributes
        writer(0, 1, 2, // first attribute has 3 components
               0, 1, 2, // second attribute has also 3 components
               0, 1);   // third attribute has only 2
    }

    vertexBuffer.unmap(writer);
}

offset (Optional)

The zero-based index of the first vertex to map. If it is not specified the whole VertexBuffer will be mapped.

count (Optional)

The number of vertices to map. If it is not specified all the vertices after and including offset will be mapped.

Returns a vertex writer. The writer can be called once for each mapped vertex to replace each of the components of every attribute.

9.8.2.3. unmap

Summary

Communicate to the VertexBuffer that write access to a mapped region is no longer required.

Syntax

var writer = vertexBuffer.map(firstVertexToMap, numVerticesToMap);
if (writer)
{
    // Do something with the writer here

    vertexBuffer.unmap(writer);
}

writer

The vertex writer returned by a previous call to map.

This method must be called if map returns a valid writer.

9.8.3. Properties

9.8.3.1. numVertices

Summary

Number of vertices stored on the VertexBuffer.

Syntax

var numVertices = vertexBuffer.numVertices;

Note

Read Only

9.8.3.2. numAttributes

Summary

Number of attributes per vertex.

Syntax

var numAttributes = vertexBuffer.numAttributes;

Note

Read Only

9.8.3.3. attributes

Summary

Array of strings with the format names of each vertex attribute.

Syntax

var vertexAttributesArray = vertexBuffer.attributes;

Note

Read Only

9.8.3.4. stride

Summary

The number of total components per vertex. Each vertex attribute can have up to 4 components depending on the attribute format.

Syntax

var vertexBufferStride = vertexBuffer.stride;

Note

Read Only

9.8.3.5. dynamic

Summary

True if the VertexBuffer was created as dynamic and hence can be modified at runtime, false otherwise.

Syntax

var isDynamic = vertexBuffer.dynamic;

Note

Read Only