parseFileOBJ.R

#' Convert String Matrix to Numeric Matrix
#'
#' @param m string matrix
#'
#' @return numeric matrix
#' @export

numericMatrix = function(m)
{
  
  m = as.matrix(m);
  mdim = dim(m);
  
  nm <- mapply(m, FUN=as.numeric);
  matrix(data=nm, nrow=mdim[1], ncol=mdim[2])
  
}


#' Convert String List of "f" to numeric multi-dimensional array
#'
#' @param fobj 
#'
#' @return fn, multidimension array of rows, cols, and values
#' @export
#'

numericF = function(fobj)
{
  
  rdim = dim(fobj)[1];  # rows
  cdim = dim(fobj)[2];  # cols
  ddim = 3;
  
  fn = array(NA,dim=c(rdim,cdim,ddim));
  
  
  for(rn in 1:rdim)
    {
    for(cn in 1:cdim)
      {
      rcdat = fobj[rn,cn];
      fdat = as.numeric(unlist(strsplit(rcdat,"/",fixed=T))); # basic numeric case
      fn[rn,cn,] = fdat;
      }
    }
  
  
  
  #fn[1:10,1:4,1:3]
  
  fn;
  

    }



#' Internally equivalent to rgl 'readOBJ'
#'
#' @param rawobj Raw object read in using parseFileOBJ
#' 
#' rgl::readOBJ
#' hand <- readLines("hand.OBJ")
#' poly <- grepl("^f ", hand)
#' hand[poly] <- gsub("/[^ ]+", "", hand[poly])
#' handmesh <- readOBJ(textConnection(hand))
#' 
#' mymesh = buildBasicMeshFromOBJ(parseFileOBJ("hand.OBJ"));
#' 
#' These appear to be equivalent in the basic form
#'
#' @return list object equivalent to readOBJ output
#' @export
#'

buildBasicMeshFromOBJ <- function(rawobj)
{
  
  mesh = list();
      vb = as.matrix(rawobj$v);
      vb = cbind(vb,1);
    mesh$vb = t(vb);
    mesh$it = matrix(0,nrow=3,ncol=0);
    mesh$primitivetype = "triangle";
    mesh$ib = t(as.matrix(rawobj$fn[,,1]));
    
    attr(mesh,"class") = c("mesh3d","shape3d");
  
  mesh;  
}

#' Parse file of type OBJ
#'
#' Specification for OBJ format can be found here:
#' http://www.martinreddy.net/gfx/3d/OBJ.spec
#' 
#' Requires gdata::trim
#' 
#' @param filename 
#'
#' @return list 'rawobj' with all details from the file
#' @export
#'
#' @examples
#' rawobj = parseFileOBJ("hand.obj");
parseFileOBJ <- function(filename)
{
  
  
  
  linestxt <- readLines(filename)                 # read all lines
  linestxt = gsub("\\s+"," ",gdata::trim(linestxt));  # replace multiple spaces with single space
  linesobj = strsplit(linestxt," ",fixed=T);      # split on spaces
  
  
  rawobj = list();
  rawobj$lines = c();
  rawobj$comments = c();
  

  
  for(i in 1:length(linesobj))
  {
    hir = gdata::trim(linesobj[[i]]);
    key = hir[1]; 
    rdat = hir[-1]; 
    rlen = length(rdat);
    rstr = paste(rdat,collapse=" ");
    if(!is.na(key))
    {
    if (key=="#") {
      rawobj$lines = c(rawobj$lines,"comments");
      rawobj$comments = c(rawobj$comments,rstr);
      } else { rawobj$lines = c(rawobj$lines,key); 
              if(is.null(rawobj[[key]])) { rawobj[[key]] = rdat; } else 
                {  rawobj[[key]] = rbind(rawobj[[key]],rdat);}
      }
    }
  }
  
  
  if(!is.null(rawobj[["v"]])) { rawobj[["v"]] = numericMatrix(rawobj[["v"]]);  }
  if(!is.null(rawobj[["vn"]])) { rawobj[["vn"]] = numericMatrix(rawobj[["vn"]]);  }
  if(!is.null(rawobj[["vt"]])) { rawobj[["vt"]] = numericMatrix(rawobj[["vt"]]);  }
  
  # "f" could be numeric (f 1 2 3 4) or (f -4 -3 -2 -1) or references to v,vn,vt (f 1/1/1 2/2/2 3/3/3 4/4/4) or (f v/vt/vn v/vt/vn v/vt/vn v/vt/vn) or (f 1//1 2//2 3//3 4//4)
  # rdat = c("1102/9904/4404","2981/9909/4404","3943/9910/4404","2854/9905/4404");
  # rdat = c('1//1','2//2','3//3',4//4');
  
  if(!is.null(rawobj[["f"]])) { rawobj[["fn"]] = numericF(rawobj[["f"]]);  }
  
  
  
  rawobj;
  
}