Hey @alcol68,

We cannot always answer right away.

A layer shader stores its layer in a data type unexposed to the Python and public C++ API (BlendDataType) in its parameter SLA_LAYER_BLEND. Which is why this abstraction with LayerShaderLayer exists.

Your code went into the right direction, as you probably have to use id decomposition ((param, sub_channel)) when you want to access such value without the layer abstraction. The issue with your code is that you do not take into account that this must be a dynamic description, i.e., you have to encode which layer you mean.

I currently do not have much time due to approaching releases and would probably only find time next week to have a closer look. Here is how the data type reroutes parameter set events internally. As you can see, it encodes both the layer and the item into a desc level. How this works exactly and if this translates to Python, I would have to find out myself.

static const Int32 BLEND_DATA_OFFSET = 10000; static const Int32 BLEND_DATA_STEP_SIZE = 20; Bool Foo::GetParameter(...) { iBlendDataType *s = (iBlendDataType*)data; if (!s) return false; Int32 lID = id[0].id; lID -= BLEND_DATA_OFFSET; DescID idNew = id << 1; // push out id[0] Int32 lItem = lID % BLEND_DATA_STEP_SIZE; Int32 lLayer = lID / BLEND_DATA_STEP_SIZE; //BlendLayer is what you know as LayerShaderLayer BlendLayer* pLayer = s->m_BlendLayers.SearchLayer(lLayer); if (!pLayer) return false; pLayer->GetParameter(lItem, idNew, t_data, flags); return CustomDataTypeClass::GetParameter(data, id, t_data, flags); }

Cheers,
Ferdinand

Check C4D version for using Fields