---
title: "Importing terrainr tiles into Unity"
output: rmarkdown::html_vignette
vignette: >
  %\VignetteIndexEntry{Importing terrainr tiles into Unity}
  %\VignetteEngine{knitr::rmarkdown}
  %\VignetteEncoding{UTF-8}
---

```{r, include = FALSE}
knitr::opts_chunk$set(
  collapse = TRUE,
  comment = "#>"
)
```

terrainr advertises itself as a package for landscape visualization in R and 
[Unity](https://unity.com/). This vignette focuses on the Unity half of the 
equation -- specifically, on how to mostly-automatically import tiles into 
Unity. If you're interested in the R half of the package, refer to 
(the overview vignette)[overview.html]. Note that this vignette will assume you 
already have Unity installed on your computer.

In order to import terrain tiles into Unity, we will first need to have some 
data worth importing! For the purposes of this vignette, we'll be using data 
from the USGS National Map downloaded using `get_tiles`, but note that you can
use _any_ raster data for this process.

First things first, I'm going to use the `geocode_OSM` function from `tmaptools` 
to get the latitude and longitude of Zion National Park, out in Utah. We'll use
this area for our visualization today:

```{r, eval = FALSE}
zion <- tmaptools::geocode_OSM("Zion National Park")$coords
```

Our `zion` object now contains the x and y coordinates for a spot near the 
middle of Zion National Park. Let's go ahead and turn that into an `sf` object,
then use `set_bbox_side_length` to add a buffer around the point coordinates -- 
we'll download data for the entire 8 kilometer square around the central point:

```{r, eval = FALSE}
library(terrainr)
library(sf)
library(magrittr)

zion <- data.frame(x = zion[["x"]], y = zion[["y"]]) %>% 
  st_as_sf(coords = c("x", "y"), crs = 4326) %>% 
  set_bbox_side_length(8000)
```

And now we can go ahead and download data for our area of interest, then merge 
the downloaded tiles into individual rasters. For more on this process or what
these functions do, check out (the overview vignette)[overview.html]. 

Fair warning -- downloading this amount of data can take a bit of time! You can
optionally add a progress bar to the `get_tiles` download by calling 
`library(progressr)` and then `handlers(global = TRUE)` before running this 
code.

```{r, eval = FALSE}
merged_tiles <- zion %>%
  get_tiles(services = c("elevation", "ortho")) %>% 
  lapply(merge_rasters)
```

We've now got our data downloaded! All that's left is to import these tiles into
Unity.

As of terrainr 0.7.0, the way to do this is via the function `make_unity`. 
Assuming you have Unity installed on your computer, we can go ahead and 
import our terrain into a brand new project, named `zion`, through the 
following:

```{r eval = FALSE}
make_unity(
  project = "zion",
  heightmap = merged_tiles$elevation,
  overlay = merged_tiles$ortho
)
```

This will create a new folder, named `zion`, containing our Unity project. 
Open that project in Unity, and then open the scene (either using `Ctrl+O`
or `File -> Open Scene`) named `Scenes/terrainr_scene.unity`. 
Double click on one of the terrain tiles and you'll zoom out to see the
entire terrain:

```{r, echo = FALSE}
knitr::include_graphics("terrain_surface.jpg")
```

You can now move around your surface by right clicking on the image and moving
around with the W-A-S-D keys on your keyboard. Note that your movement speed 
starts off very slow, and then accelerates over time (especially if you
press and hold the "shift" key).

And ta-da, you have a surface in Unity! You can go ahead and customize the scene
further (I'll usually then click on "Directional Light" and change "Render Mode" 
to "Not Important" and "Shadow Type" to "No Shadows"), fly around and across
the scene, or do whatever else you want!


