Parameters are accessed with C4DAtom::GetParameter()/ C4DAtom::SetParameter(). See Parameter IDs.
Parameter: Color
THINFILMSHADER_LAYERCOLOR
Parameter: Texture
THINFILMSHADER_LAYERCOLOR_TEX_LINK
Parameter: Mix Strength
THINFILMSHADER_LAYERMIXSTRENGTH
Parameter: Thickness (nm)
THINFILMSHADER_AVERAGETHICKNESS
Parameter: Variation (nm)
THINFILMSHADER_RELATIVETHICKNESS
Parameter: Texture
THINFILMSHADER_RELATIVECHANGE_TEX_LINK
Parameter: IOR Preset
THINFILMSHADER_IOR_PRESET
Parameter: IOR
THINFILMSHADER_IOR
Parameter: Spectral Samples
THINFILMSHADER_NUMSPECTRALSAMPLE