# Unity [FBX] Material Index problem

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Hi all,

I have a problem to get good material index with FBX, the problem is not the FBX because Unity open it good.

The problem is not the UV because I have rendered them and I see good UV on the mesh.

I show you the code I use to get the material index :

int GetMappingIndex( const FbxLayerElement::EMappingMode& MappingMode, const int PolygonIndex, const int PolygonVertexIndex, const int VertexIndex )
{
switch( MappingMode )
{
case FbxLayerElement::eAllSame         : return 0;
case FbxLayerElement::eByControlPoint  : return VertexIndex;
case FbxLayerElement::eByPolygonVertex : return PolygonIndex * 3 + PolygonVertexIndex;
case FbxLayerElement::eByPolygon       : return PolygonIndex;
}
return -1;
}

int GetMaterialIndex( FbxScene* Scene, FbxMesh* FBXMesh, const int LayerIndex, const int PolygonIndex, const int PolygonVertexIndex, const int VertexIndex )
{
// Check for valid params.
if( LayerIndex < 0 || LayerIndex > FBXMesh->GetLayerCount() )
return -1;

// Get the node of the mesh.
FbxNode* Node = FBXMesh->GetNode();

// Check if the node is valid.
if( Node == NULL )
return -1;

// Get the layer element material.
FbxLayerElementMaterial* FBXMaterial = FBXMesh->GetLayer( LayerIndex )->GetMaterials();

// Check if the layer element material is valid.
if( FBXMaterial )
{
// Get the mapping index.
const int MappingIndex = GetMappingIndex( FBXMaterial->GetMappingMode(), PolygonIndex, 0, VertexIndex );

// Check if the mapping index is valid.
if( MappingIndex < 0 )
return -1;

// Get the reference mode.
const FbxLayerElement::EReferenceMode ReferenceMode = FBXMaterial->GetReferenceMode();

// Check the reference mode.
if( ReferenceMode == FbxLayerElement::eDirect )
{
// Check if the mapping index is valid.
if( MappingIndex < Node->GetMaterialCount() )
{
// Get the node material.
FbxSurfaceMaterial* NodeMaterial = Node->GetMaterial( MappingIndex );

// Find the node material in the scene.
for( int i = 0; i < Scene->GetMaterialCount(); ++i )
{
FbxSurfaceMaterial* SceneMaterial = Scene->GetMaterial( i );
if( SceneMaterial == NodeMaterial )
return i;
}
}
}
else if( ReferenceMode == FbxLayerElement::eIndexToDirect )
{
// Get the material index array.
const FbxLayerElementArrayTemplate< int >& MaterialIndexArray = FBXMaterial->GetIndexArray();

// Check if the mapping index is valid.
if( MappingIndex < MaterialIndexArray.GetCount() )
{
// Get the material index.
const int Index = MaterialIndexArray.GetAt( MappingIndex );

// Check if the index is valid.
if( Index < Node->GetMaterialCount() )
{
// Get the node material.
FbxSurfaceMaterial* NodeMaterial = Node->GetMaterial( Index );

// Find the node material in the scene.
for( int i = 0; i < Scene->GetMaterialCount(); ++i )
{
FbxSurfaceMaterial* SceneMaterial = Scene->GetMaterial( i );
if( SceneMaterial == NodeMaterial )
return i;
}
}
}
}
}

// Return invalid material index.
return -1;
}
// Each polygon (triangle).
for( DE::Int32 p = 0; p < FBXMesh->GetPolygonCount(); ++p )
{
// Each polygon vertex.
for( DE::Int32 pv = 0; pv < 3; ++pv )
{
...
...
}

// Set the face material ID.
const DE::Int32 MaterialControlPointIndex = FBXMesh->GetPolygonVertex( p, 0 );
NewFace.MaterialID = GetMaterialIndex( m_Scene, FBXMesh, 0, p, 0, MaterialControlPointIndex );
}

Thanks for the help

Edited by Alundra

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