plot_fit <- function(sobj, mthd, ncomp, grid_size = 25) {
  require(plot3D)
  x <- with(sobj, c(X[, 1]))
  y <- with(sobj, c(X[, 2]))
  z <- with(sobj, c(Y[, 1]))
  method <- get(mthd)(z ~ x + y)
  grid_size <- grid_size
  x_pred <- seq(min(x), max(x), length.out = grid_size)
  y_pred <- seq(min(y), max(y), length.out = grid_size)
  xy <- expand.grid(x = x_pred, y = y_pred)
  z_pred <- matrix(predict(method, newdata = xy, ncomp = ncomp), grid_size, grid_size)
  fitpoints <- predict(method, ncomp = ncomp)
  par(family = "mono")
  scatter3D(x, y, z, ticktype = "detailed", pch = 21, bty = "g", col = "grey50",
            cex = 1, theta = 55, phi = 0, colkey = FALSE, bg = viridis::viridis(length(z)),
            main = paste("Method:", toupper(mthd), "|", ncomp, "Components"),
            xlab = "Predictor 1", ylab = "Predictor 2", zlab = "Response",
            surf = list(x = x_pred, y = y_pred, z = z_pred,  shade = 0.1,
                        fit = fitpoints, facets = NA, col = viridis::viridis(length(z)),
                        alpha = 0.2, lcol = viridis::viridis(length(z))))
  scatter3D(x, y, fitpoints, add = TRUE, colkey = FALSE, pch = 16,
            col = viridis::viridis(length(fitpoints)),
            cex = 0.7)
}
plotly_fit <- function(sobj, mthd, ncomp, grid_size = 25) {
  require(plotly)
  x <- with(sobj, c(X[, 1]))
  y <- with(sobj, c(X[, 2]))
  z <- with(sobj, c(Y[, 1]))
  method <- get(mthd)(z ~ x + y)
  grid_size <- grid_size
  x_pred <- seq(min(x), max(x), length.out = grid_size)
  y_pred <- seq(min(y), max(y), length.out = grid_size)
  xy <- expand.grid(x = x_pred, y = y_pred)
  z_pred <- matrix(predict(method, newdata = xy, ncomp = ncomp), grid_size, grid_size)
  fitpoints <- predict(method, ncomp = ncomp)

  # custom grid style
  axx <- list(
    gridcolor='rgb(255, 255, 255)',
    zerolinecolor='rgb(255, 255, 255)',
    showbackground=TRUE,
    backgroundcolor='rgb(230, 230,230)'
  )
  # The Plot
  plot_ly() %>%
    add_markers(
      x = x, y = y, z = z,
      showlegend = FALSE,
      marker = list(
        color = "CadetBlue",
        size = 5,
        line = list(
          color = "black",
          width = 0.5
        )
      )) %>%
    add_surface(
      x = ~x_pred,
      y = ~y_pred,
      z = ~z_pred,
      showscale = FALSE,
      inherit = FALSE,
      opacity = 0.7
    ) %>%
    layout(
      title = paste("Method:", toupper(mthd), "; ", ncomp, "Components"),
      scene = list(
        xaxis = append(axx, list(title = "Predictor 1", range = c(-2, 2))),
        yaxis = append(axx, list(title = "Predictor 2", range = c(-2, 2))),
        zaxis = append(axx, list(title = "Response", range = c(-4, 4))),
        camera=list(
          eye = list(x=-1.8, y=1.8, z=0.8)
        )
      )
    )
}