Stream Linkage

// Create our position stream
auto PositionStream = FRealtimeMeshStream::Create<FVector3f>(FRealtimeMeshStreams::Position);

// Create our tangents stream
auto TangentsStream = FRealtimeMeshStream::Create<FRealtimeMeshTangentsNormalPrecision>(FRealtimeMeshStreams::Tangents);

// Create our linkage that we'll use to bind the vertex streams together
FRealtimeMeshStreamLinkage VerticesLinkage;

// Bind the position stream, with a deafult value of zero vector.
// We can do this simply because we know the type
VerticesLinkage.BindStream(PositionStream, FRealtimeMeshStreamDefaultRowValue::Create(FVector3f::ZeroVector));

// Bind the tangents stream, we create the default value by passing it our wanted value, and getting the final layout from the stream.
// This lets it do the conversion once and then just blit this value into the stream.
VerticesLinkage.BindStream(TangentsStream, FRealtimeMeshStreamDefaultRowValue::Create(
    FRealtimeMeshTangentsNormalPrecision(FVector3f::ZAxisVector, FVector3f::XAxisVector),
    TangentsStream.GetLayout()));

// We can setup the two builders to make working with the streams easier    
TRealtimeMeshStreamBuilder<FVector3f> PositionStreamBuilder(PositionStream);
TRealtimeMeshStreamBuilder<FRealtimeMeshTangentsHighPrecision, FRealtimeMeshTangentsNormalPrecision> TangentsStreamBuilder(TangentsStream);

// This will add the position to the position stream. It will also set the tangents stream size to the same size and default the value
// You should *NOT* use .Add on the secondary streams when setting the value, you can just used the indexed set. 
// It doesn't matter which stream you call .Add() on, it will resize them all.
int32 Index = PositionStreamBuilder.Add(FVector3f(1, 0, 0));

// Here we just set the tangent entry for this index
// If you call .Add() again then you'll end up with 2 vertices in both streams, instead of 1 vertex with the tangent set for the existing vertex
TangentsStreamBuilder[Index] = FRealtimeMeshTangentsHighPrecision(FVector3f(0, 1, 0), FVector3f(0, 0, 1));