R/surface.R

In JerBoon/raytrace:

#---------------------------------------------------------------------
#' Validate parameters, and return a valid surface object
#'
#' @param rgb Either a 3 value vector of numbers in teh range 0 to 1, or a function which will return the equivalent.
#'     The function, if present, will be passed the values of *north* and *east* as returned by the object's intersection.
#'     The function allow interesting surface properties to be easily constructed, for example patterned, image mapping, smoothing or 
#'     randomisation.
#' @param transparency The proportion of incident light which will be refracted by the surface. 1 minus this value will be reflected.
#'     Default = 0, i.e. a non-transparent surface.
#' @param matteness The proportion of matte reflectivity of the surface. 1 minus this value will be reflected as mirror reflection.
#'     Default = 0, i.e the surface has mirror reflectivity
#'
#' @return A validated surface object. Ray tracing functions in this package expect all solid objects to have a valid surface property.
#' 
#' @export
#'
#' @examples
#'   surf <- RT.Surface(rgb=c(1,1,0), transparency=1)

# ultimately I think I need...
#  - colour
#  - matteness - the proportion of matte reflectivity for the surface. If 0, it's a mirror surface, if 1 it's fully matte 
#  - transparency - if 0, then it's not, 1 it's fully transparent
#      - if > 0 also need outside andinside refractive index

RT.Surface <- function(rgb, matteness=0, transparency=0) {

  #----- Some validation checks -----
  if (((typeof(rgb) != "double") ||
       length(rgb) != 3 ||
       min(rgb) < 0 ||
       max(rgb) > 1)
      && typeof(rgb) != "closure") {
    print("RT.Surface: rgb should be a 3 number vector, values between 0 and 1, OR a function which'll return that")
    return(NA)
  }
  if ((typeof(matteness) != "double") ||
      length(matteness) != 1 ||
      matteness < 0 || matteness > 1) {
    print("RT.Surface: matteness should be a scalar value between 0 and 1")
    return(NA)
  }
  if ((typeof(transparency) != "double") ||
      length(transparency) != 1 ||
      transparency < 0 || transparency > 1) {
    print("RT.Surface: transparency should be a scalar value between 0 and 1")
    return(NA)
  }

  r <- list(rgb=rgb,
            matteness=matteness,
            transparency=transparency)

  class(r) = append(class(r),"RTSurface")
  return(r)
}