Add configuration file

Cargo.toml

@@ -37,10 +37,18 @@ winit       = "0.26.1"
 version  = "3.1.6"
 features = ["derive"]
 
+[dependencies.figment]
+version  = "0.10.6"
+features = ["env", "toml"]
+
 [dependencies.fj]
 version = "0.5.0"
 path    = "fj"
 
+[dependencies.serde]
+version  = "1.0.136"
+features = ["derive"]
+
 [dependencies.tracing-subscriber]
 version  = "0.3.9"
 features = ["env-filter", "fmt"]

fj.toml

@@ -0,0 +1,7 @@
+# The default path that models are loaded from. If the `--model` argument is a
+# relative path, it is assumed to be relative to `default_path`.
+default_path = "models"
+
+# The default models that is loaded, if none is specified. If this is a relative
+# path, it should be relative to `default_path`.
+default_model = "star"

src/args.rs

@@ -4,8 +4,8 @@ use std::path::PathBuf;
 #[derive(clap::Parser)]
 pub struct Args {
     /// The model to open
-    #[clap(short, long, default_value = "cuboid")]
-    pub model: PathBuf,
+    #[clap(short, long)]
+    pub model: Option<PathBuf>,
 
     /// Export model to this path
     #[clap(short, long)]

src/config.rs

@@ -0,0 +1,24 @@
+use std::path::PathBuf;
+
+use anyhow::Context as _;
+use figment::{
+    providers::{Env, Format as _, Toml},
+    Figment,
+};
+use serde::Deserialize;
+
+#[derive(Debug, Deserialize)]
+pub struct Config {
+    pub default_path: PathBuf,
+    pub default_model: PathBuf,
+}
+
+impl Config {
+    pub fn load() -> Result<Self, anyhow::Error> {
+        Figment::new()
+            .merge(Toml::file("fj.toml"))
+            .merge(Env::prefixed("FJ_"))
+            .extract()
+            .context("Error loading configuration")
+    }
+}

src/main.rs

@@ -1,5 +1,6 @@
 mod args;
 mod camera;
+mod config;
 mod debug;
 mod graphics;
 mod input;
@@ -27,6 +28,7 @@ use crate::math::Scalar;
 use crate::{
     args::Args,
     camera::Camera,
+    config::Config,
     debug::DebugInfo,
     graphics::{DrawConfig, Renderer},
     kernel::shapes::ToShape as _,
@@ -50,7 +52,11 @@ fn main() -> anyhow::Result<()> {
         .init();
 
     let args = Args::parse();
-    let model = Model::new(args.model);
+    let config = Config::load()?;
+    let model = Model::new(
+        config.default_path,
+        args.model.unwrap_or(config.default_model),
+    );
 
     let mut parameters = HashMap::new();
     for parameter in args.parameters {

src/model.rs

@@ -12,8 +12,8 @@ pub struct Model {
 }
 
 impl Model {
-    pub fn new(rel_path: PathBuf) -> Self {
-        let mut path = PathBuf::from("models");
+    pub fn new(base_path: PathBuf, rel_path: PathBuf) -> Self {
+        let mut path = base_path;
         path.push(rel_path);
 
         Self { path }