Parameters are accessed with C4DAtom::GetParameter()/ C4DAtom::SetParameter(). See Parameter IDs.
Parameter: Cache Primary Rays
HAIR_RENDER_PHYSICAL_CACHE_PRIMARYParameter: Cache Secondary Rays
HAIR_RENDER_PHYSICAL_CACHE_SECONDARYParameter: Cache Blurry Rays
HAIR_RENDER_PHYSICAL_CACHE_BLURRYParameter: Cache GI Rays
HAIR_RENDER_PHYSICAL_CACHE_GIParameter: GI Sampling
HAIR_RENDER_PHYSICAL_GIParameter: Sampling
HAIR_RENDER_COLOR_SAMPLINGParameter: GI Quality
HAIR_RENDER_PHYSICAL_GI_QUALITYParameter: Render
HAIR_RENDER_TYPEParameter: AA Quality
HAIR_RENDER_AA_QUALITYParameter: Type
HAIR_RENDER_AA_MODEParameter: Filter
HAIR_RENDER_AA_USERParameter: Cast Shadows
HAIR_RENDER_SHADOWSParameter: Transparency
HAIR_RENDER_TRANSPARENCYParameter: Reflection/Refraction/Traced Shadows
HAIR_RENDER_TRACINGParameter: Tracing Memory
HAIR_RENDER_MEMORY_USEParameter: Shadows
HAIR_RENDER_SHADOW_TYPEParameter: Trans. Threshold
HAIR_RENDER_SHADOW_TRANS_ACCURACYParameter: Depth Threshold
HAIR_RENDER_SHADOW_DIST_ACCURACYParameter: Antialiasing
HAIR_RENDER_SHADOW_AA_LEVELParameter: Filter
HAIR_RENDER_SHADOW_AA_USERParameter: Sample Size
HAIR_RENDER_SHADOW_SAMPLE_SIZEParameter: Shadow Map
HAIR_RENDER_SHADOWS_MAPParameter: Resolution
HAIR_RENDER_SHADOW_CACHE_SIZEParameter: Traced Width
HAIR_RENDER_SHADOW_WIDTHParameter: Mode
HAIR_RENDER_LIGHTS_MODEParameter: Lights
HAIR_RENDER_LIGHTSParameter: Hair
HAIR_RENDER_OBJECTS_HAIRParameter: Polygon
HAIR_RENDER_OBJECTS_POLYGONParameter: Spline
HAIR_RENDER_OBJECTS_SPLINEParameter: Particle
HAIR_RENDER_OBJECTS_PARTICLEParameter: Length
HAIR_RENDER_HAIR_LENGTHParameter: Count
HAIR_RENDER_HAIR_COUNTParameter: Mode
HAIR_RENDER_OBJECTS_MODEParameter: Objects
HAIR_RENDER_OBJECTSParameter: Image
HAIR_RENDER_MP_RGBParameter: Depth
HAIR_RENDER_MP_DEPTHParameter: Alpha
HAIR_RENDER_MP_ALPHAParameter: Split Back
HAIR_RENDER_MP_SPLIT_BACKParameter: Color
HAIR_RENDER_MP_COLORParameter: Diffuse
HAIR_RENDER_MP_DIFFUSEParameter: Specular
HAIR_RENDER_MP_SPECULARParameter: Secondary
HAIR_RENDER_MP_SECONDARY_SPECULARParameter: Received Shadows
HAIR_RENDER_MP_RECIEVE_SHADOWParameter: Self-Shadows
HAIR_RENDER_MP_SELF_SHADOWParameter: Illumination
HAIR_RENDER_MP_ILLUMINATION