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A NormalTag stores normal vectors for a (polygon) object. For each polygon a set of four vectors is stored ( NormalStruct ). The class NormalTag is based on VariableTag so the typical workflows on handling tags apply, see BaseTag and VariableTag Manual .

NormalTag objects are an instance of Tnormal .

Allocation/Deallocation

NormalTag instances are created with the usual tools.

NormalTag::Alloc() : Creates a new NormalTag .
NormalTag::Free() : Destroys the given NormalTag .

// This example checks if the given object hosts a Normal tag. // If not, a Normal tag is created.

NormalTag * normalTag = static_cast< NormalTag * > (polyObject-> GetTag ( Tnormal )); if (normalTag == nullptr ) { const Int32 polyCnt = polyObject-> GetPolygonCount (); normalTag = NormalTag::Alloc (polyCnt); if (normalTag == nullptr ) return maxon::OutOfMemoryError( MAXON_SOURCE_LOCATION ); polyObject-> InsertTag (normalTag); }

编辑

The normal vectors stored in a NormalTag are accessed by obtaining data handles that are used with static functions:

NormalTag::GetDataAddressR() : Returns a handle to the read-only normal vectors.
NormalTag::GetDataAddressW() : Returns a handle to the writeable normal vectors.
NormalTag::Get() : Returns the normal vectors for the given polygon index.
NormalTag::Set() : Sets the normal vectors for the given polygon index.
NormalTag::Copy() : Copies the normal vectors from the given handle to the other handle.

// This example calculates normal vectors, changes them and stores them in the given Normal tag.

// make sure a Phong tag exists if (polyObject-> GetTag ( Tphong ) == nullptr ) { BaseTag * phongTag = polyObject-> MakeTag ( Tphong ); if (phongTag == nullptr ) return maxon::OutOfMemoryError( MAXON_SOURCE_LOCATION ); } Random random; NormalHandle handle = normalTag-> GetDataAddressW (); for ( Int32 i = 0; i < polygonCount; ++i) { const CPolygon polygon = polygons[i];

// calculate default face normal 向量 normal = CalcFaceNormal (points, polygon); NormalStruct normals;

// add random variation normal. x += ((random. Get01 () * 0.2) - 0.1); normal. y += ((random. Get01 () * 0.2) - 0.1); normal. z += ((random. Get01 () * 0.2) - 0.1); normal. Normalize ();

// define polygon normals normals. a = normal; normals. b = normal; normals. c = normal; normals. d = normal; NormalTag::Set (handle, i, normals); } polyObject-> 消息 ( MSG_UPDATE );