CustomDataTag Manual

Table of Contents

• About
• Creation
• Data Type
• Data
• Further Reading

About

A CustomDataTag is a BaseTag that stores custom point or polygon data. It is a generalized tag type to store mesh-based data like normals, UVs, vertex colors etc. It can replace dedicated tags like NormalTag, UVWTag or VertexColorTag.

A CustomDataTag gives access to data and functionality implemented with maxon::MeshAttribute, maxon::MeshAttributeClassInterface, maxon::CustomDataTagClassInterface and maxon::CustomDataTagDisplayInterface (see Mesh Attributes Interfaces).

Creation

A CustomDataTag object is created using the usual tools and the specific data type ID:

• CustomDataTag::Alloc(): Creates a new CustomDataTag.
• CustomDataTag::Free(): Deletes the given CustomDataTag.
• CustomDataTag::InitData(): Initializes the data. Must be called after the tag is added to the PolygonObject.
• CustomDataTag::Resize(): Resizes the internal data.

  // This example creates a CustomDataTag of the given type, adds
  // it to the given polygon object and sets it to vertex mode.
 
  // create tag
  BaseTag* const tag = CustomDataTag::Alloc(ID_VERTEXSCALARTAG);
  if (tag == nullptr)
    return maxon::OutOfMemoryError(MAXON_SOURCE_LOCATION);
 
  // insert tag
  polygonObject->InsertTag(tag);
 
  // init tag
  CustomDataTag* const      customDataTag = static_cast<CustomDataTag*>(tag);
  customDataTag->InitData() iferr_return;
  customDataTag->SetMode(CUSTOMDATATAG_MODE::VERTEX);

Data Type

The data type stored in a given CustomDataTag is obtained with:

• CustomDataTag::GetCustomDataTagClass(): Returns the maxon::CustomDataTagClass (maxon::CustomDataTagClassInterface).
• CustomDataTag::GetDataType(): Returns the maxon::DataType. See DataType Manual.

Data

A CustomDataTag can stores either point data (CUSTOMDATATAG_MODE::VERTEX) or polygon point data (CUSTOMDATATAG_MODE::POLYVERTEX):

• CustomDataTag::GetMode(): Returns the current mode.
• CustomDataTag::SetMode(): Sets the current mode.

The number of stored elements is returned with:

• CustomDataTag::GetComponentCount(): Returns the number of stored elements.

The stored vertex data is accessed with these functions:

• CustomDataTag::GetConstVertexDataPtr(): Returns a read-only pointer to the data at the given index.
• CustomDataTag::GetVertexDataPtr(): Returns a pointer to the data at the given index.
• CustomDataTag::SetVertexDataPtr(): Sets the data at the given index.
• CustomDataTag::GetVertexAttribute(): Returns the maxon::MeshAttribute at the given index.
• CustomDataTag::SetVertexAttribute(): Sets the maxon::MeshAttribute at the given index.
• CustomDataTag::GetVertexData(): Returns a read-only reference to the data at the given index.
• CustomDataTag::GetVertexDataRef(): Returns a reference to the data at the given index. Uses GetVertexDataPtr() internally
• CustomDataTag::SetVertexData(): Sets the data at the given index.

  // This example fills the given CustomDataTag with random values for each point.
 
  // get number of components
  const Int count = customDataTag->GetComponentCount();
 
  // for each component, set a random value
  maxon::LinearCongruentialRandom<maxon::Float32> random;
  for (Int32 i = 0; i < count; ++i)
  {
    Float value = random.Get01();
    customDataTag->SetVertexData<Float>(i, std::move(value));
  }

The stored polygon data is accessed with:

• CustomDataTag::GetConstPolyVertexDataPtr(): Returns a read-only pointer to the data at the given polygon and point index.
• CustomDataTag::GetPolyVertexDataPtr(): Returns a pointer to the data at the given polygon and point index.
• CustomDataTag::SetPolyVertexDataPtr(): Sets the data at the given polygon and point index.
• CustomDataTag::GetConstPolygonDataPtr(): Returns a read-only pointer to maxon::PolyData for the given polygon index.
• CustomDataTag::GetPolygonDataPtr(): Returns a pointer to maxon::PolyData for the given polygon index.
• CustomDataTag::SetPolygonDataPtr(): Sets the maxon::PolyData for the given polygon index.
• CustomDataTag::GetPolyVertexAttribute(): Returns the maxon::MeshAttribute for the given polygon and point index.
• CustomDataTag::SetPolyVertexAttribute(): Sets the maxon::MeshAttribute for the given polygon and point index.
• CustomDataTag::GetPolygonAttribute(): Returns the maxon::PolyData maxon::MeshAttribute for the given polygon index.
• CustomDataTag::SetPolygonAttribute(): Sets the maxon::PolyData maxon::MeshAttribute for the given polygon index.
• CustomDataTag::GetPolyVertexData(): Returns the read-only data for the given polygon and point index.
• CustomDataTag::GetPolyVertexDataRef(): Returns a reference to the data for the given polygon and point index.
• CustomDataTag::SetPolyVertexData(): Sets the data for the given polygon and point index.
• CustomDataTag::GetPolygonData(): Returns the maxon::PolyData for the given polygon index.
• CustomDataTag::GetPolygonDataRef(): Returns a reference to the maxon::PolyData for the given polygon index.
• CustomDataTag::SetPolygonData(): Sets the maxon::PolyData for the given polygon index.

  // This example fills the given CustomDataTag with random values for each polygon vertex.
 
  // get number for components
  const Int count = customDataTag->GetComponentCount();
 
  // for each polygon set random values
  maxon::LinearCongruentialRandom<maxon::Float32> random;
  for (Int32 i = 0; i < count; ++i)
  {
    // create polygon value
    maxon::Float value = random.Get01();
 
    // set each point of the given polygon to that value
    for (Int32 polyvertexIndex = 0; polyvertexIndex < 4; ++polyvertexIndex)
    {
      customDataTag->SetPolyVertexData<maxon::Float>(i, polyvertexIndex, std::move(value));
    }
  }

The maxon::PolyData template class stores data for either a triangle or quad:

• maxon::PolyData::operator[](): Returns the data for the given vertex index.
• maxon::PolyData::IsTriangle(): Returns true if the polygon is a triangle.
• maxon::PolyData::FindCornerIndex(): Returns the vertex index for the given value.
• maxon::PolyData::FindEdge(): Returns the edge index for the given values.
• maxon::PolyData::GetEdgeValues(): Gets the values for the given edge index.
• maxon::PolyData::GetMemorySize(): Returns the size of the data.
• maxon::PolyData::ToString(): Returns a maxon::String representation of the data.

        // This example accesses the polygon point values of the
        // given CustomDataTag within MeshAttributeDisplay::DisplayControl().
 
        // for each polygon of the object set the polygon vertex colors
        for (Int32 polygonIndex = 0; polygonIndex < polyCount; ++polygonIndex)
        {
          // get polygon vertex data for the given polygon
          maxon::PolyData<Float> polygonData = customDataTag->GetPolygonData<Float>(polygonIndex);
 
          // set the color of each polygon vertex
          // the CustomDataTag always stores four point values for each polygon
          for (Int32 pointIndex = 0; pointIndex < 4; ++pointIndex)
          {
            // get polygon vertex color
            // float value dispalyed in the red channel
            Color32 color { 0.0 };
            color.r = maxon::Float32(polygonData[pointIndex]);
 
            // store polygon vertex color
            // "cds" is the ControlDisplayStruct argument
            const maxon::Int colorIndex = 4 * polygonIndex + pointIndex;
            cds.vertex_color[colorIndex] = static_cast<Color32>(color);
          }
        }
 
        // show polygon vertex color
        cds.perPolygonVertexColor = true;

Further Reading

• Scene Elements
• Modeling
• Mesh Attributes Interfaces
• MAXON Data Type
• DataType Manual
• BaseTag and VariableTag Manual
• VertexColorTag Manual
• UVWTag Manual
• NormalTag Manual