Make reqwest an optional (and default) feature

Closes #211

This is just the simple solution until
#214 is fixed

Cargo.toml

@@ -16,7 +16,7 @@ all-features = true
 rustdoc-args = ["--cfg", "docsrs"]
 
 [features]
-default = ["glutin-window", "canvas", "egui-gui", "obj-io", "gltf-io", "image-io"]
+default = ["glutin-window", "canvas", "egui-gui", "obj-io", "gltf-io", "image-io", "reqwest"]
 glutin-window = ["glutin"] # Default window for desktop (only available when NOT building for the wasm32 architecture)
 canvas = [] # Default window for web (only available when building for the wasm32 architecture)
 egui-gui = ["egui"] # Additional GUI features 
@@ -30,7 +30,7 @@ log = "0.4"
 cgmath = "0.18"
 half = {version="1.8", features=["std", "num-traits", "zerocopy", "serde"]}
 thiserror = "1.0"
-reqwest = "0.11"
+reqwest = { version = "0.11", optional = true }
 serde = { version = "1.0", features = ["derive"], optional = true }
 gltf = { version = "0.16", features = ["utils"], optional = true }
 wavefront_obj = { version = "10.0", optional = true }

src/io.rs

@@ -47,8 +47,12 @@ pub enum IOError {
     #[cfg(not(target_arch = "wasm32"))]
     #[error("error while loading the file {0}: {1}")]
     FailedLoading(String, std::io::Error),
-    #[error("error while loading the file {0}: {1}")]
+    #[cfg(feature = "reqwest")]
+    #[error("error while loading the url {0}: {1}")]
     FailedLoadingUrl(String, reqwest::Error),
+    #[cfg(not(feature = "reqwest"))]
+    #[error("error while loading the url {0}: feature 'reqwest' not enabled")]
+    FailedLoadingUrl(String),
     #[error("tried to use {0} which was not loaded")]
     NotLoaded(String),
 }

src/io/loader.rs

@@ -1,6 +1,5 @@
 use crate::core::*;
 use crate::io::*;
-use reqwest::Url;
 use std::cell::RefCell;
 use std::collections::HashMap;
 use std::path::{Path, PathBuf};
@@ -255,12 +254,13 @@ fn load_from_disk(mut paths: Vec<PathBuf>, loaded: &mut Loaded) -> ThreeDResult<
     Ok(())
 }
 
+#[cfg(feature = "reqwest")]
 async fn load_urls(mut paths: Vec<PathBuf>, loaded: &mut Loaded) -> ThreeDResult<()> {
     if paths.len() > 0 {
         let mut handles = Vec::new();
         let client = reqwest::Client::new();
         for path in paths.drain(..) {
-            let url = Url::parse(path.to_str().unwrap())?;
+            let url = reqwest::Url::parse(path.to_str().unwrap())?;
             handles.push((path, client.get(url).send().await));
         }
         for (path, handle) in handles.drain(..) {
@@ -276,6 +276,16 @@ async fn load_urls(mut paths: Vec<PathBuf>, loaded: &mut Loaded) -> ThreeDResult
     Ok(())
 }
 
+#[cfg(not(feature = "reqwest"))]
+async fn load_urls(paths: Vec<PathBuf>, _loaded: &mut Loaded) -> ThreeDResult<()> {
+    if paths.is_empty() {
+        Ok(())
+    } else {
+        let url = paths[0].to_str().unwrap().to_owned();
+        Err(Box::new(IOError::FailedLoadingUrl(url)))
+    }
+}
+
 fn is_absolute_url(path: &str) -> bool {
     path.find("://").map(|i| i > 0).unwrap_or(false)
         || path.find("//").map(|i| i == 0).unwrap_or(false)