feat(rapier_testbed): autosave testbed configuration + add support for per-example settings (#799)

* feat(rapier_testbed): autosave testbed configuration + add support for per-example parameters

* feat(rapier_testbed): also save the camera position

* feat(rapier_testbed): improve ergonomics of example-specific settings

* chore: cargo fmt

* chore(rapier_testbed): small UI ergonomics improvement

* chore(rapier_testbed): clippy fixes

examples2d/Cargo.toml

@@ -14,7 +14,6 @@ enhanced-determinism = ["rapier2d/enhanced-determinism"]
 
 [dependencies]
 rand = "0.8"
-Inflector = "0.11"
 lyon = "0.17"
 usvg = "0.14"
 

examples2d/all_examples2.rs

@@ -3,8 +3,6 @@
 #[cfg(target_arch = "wasm32")]
 use wasm_bindgen::prelude::*;
 
-use inflector::Inflector;
-
 use rapier_testbed2d::{Testbed, TestbedApp};
 use std::cmp::Ordering;
 
@@ -45,38 +43,8 @@ mod s2d_pyramid;
 mod sensor2;
 mod trimesh2;
 
-fn demo_name_from_command_line() -> Option<String> {
-    let mut args = std::env::args();
-
-    while let Some(arg) = args.next() {
-        if &arg[..] == "--example" {
-            return args.next();
-        }
-    }
-
-    None
-}
-
-#[cfg(target_arch = "wasm32")]
-fn demo_name_from_url() -> Option<String> {
-    None
-    //    let window = stdweb::web::window();
-    //    let hash = window.location()?.search().ok()?;
-    //    Some(hash[1..].to_string())
-}
-
-#[cfg(not(any(target_arch = "wasm32")))]
-fn demo_name_from_url() -> Option<String> {
-    None
-}
-
 #[cfg_attr(target_arch = "wasm32", wasm_bindgen(start))]
 pub fn main() {
-    let demo = demo_name_from_command_line()
-        .or_else(demo_name_from_url)
-        .unwrap_or_default()
-        .to_camel_case();
-
     let mut builders: Vec<(_, fn(&mut Testbed))> = vec![
         ("Add remove", add_remove2::init_world),
         ("CCD", ccd2::init_world),
@@ -126,11 +94,7 @@ pub fn main() {
         (false, true) => Ordering::Less,
     });
 
-    let i = builders
-        .iter()
-        .position(|builder| builder.0.to_camel_case().as_str() == demo.as_str())
-        .unwrap_or(0);
-    let testbed = TestbedApp::from_builders(i, builders);
+    let testbed = TestbedApp::from_builders(builders);
 
     testbed.run()
 }

examples2d/s2d_pyramid.rs

@@ -21,7 +21,9 @@ pub fn init_world(testbed: &mut Testbed) {
     /*
      * Create the cubes
      */
-    let base_count = 100;
+    const BASE_COUNT_SETTING: &str = "# of basis cubes";
+    let settings = testbed.example_settings_mut();
+    let base_count = settings.get_or_set_u32(BASE_COUNT_SETTING, 100, 2..=200);
 
     let h = 0.5;
     let shift = 1.0 * h;