Parameters are accessed with C4DAtom::GetParameter()/ C4DAtom::SetParameter(). See Parameter IDs.
Parameter: Texture
XRAIN_SHADERLINK
Parameter: Direction
XRAIN_DIRECTION
Parameter: Intensity
XRAIN_INTENSITY
Parameter: Smoothness
XRAIN_SAMPLES
Parameter: Weighting
XRAIN_WEIGHTED
Parameter: Clamp UV coords
XRAIN_CLAMP
Parameter: Intensity Shader
XRAIN_WEIGHTSHADER_LINK
Parameter: Strength
XRAIN_WEIGHTSHADER_INTENSITY