Embed model template in fj-app directory, use it to generate model

Cargo.toml

@@ -3,6 +3,7 @@ resolver = "2"
 members = [
     "crates/fj",
     "crates/fj-app",
+    "crates/fj-app/model-template",
     "crates/fj-export",
     "crates/fj-host",
     "crates/fj-interop",

crates/fj-app/build.rs

@@ -1,8 +1,7 @@
 use ignore::WalkBuilder;
 use std::{collections::HashSet, env, ffi::OsStr, fs::File, path::Path};
 
-static NEW_MODEL_TEMPLATE: &str = "star";
-static EXTRA_IGNORED_FILES: &[&str] = &["star.png", "README.md"];
+static EXTRA_IGNORED_FILES: &[&str] = &["README.md"];
 
 fn main() {
     create_new_model_tar();
@@ -14,13 +13,7 @@ fn create_new_model_tar() {
     let mut tar_builder = tar::Builder::new(file);
 
     let manifest_dir = env::var_os("CARGO_MANIFEST_DIR").unwrap();
-    let fornjot_root_path = Path::new(&manifest_dir)
-        .ancestors()
-        .nth(2)
-        .expect("Failed to get 'fornjot_root_path' path");
-
-    let new_model_path =
-        fornjot_root_path.join("models").join(NEW_MODEL_TEMPLATE);
+    let new_model_path = Path::new(&manifest_dir).join("model-template");
 
     let extra_ignored_files = EXTRA_IGNORED_FILES
         .iter()

crates/fj-app/model-template/Cargo.toml

@@ -0,0 +1,7 @@
+[package]
+name = "model-template"
+version = "0.1.0"
+edition = "2021"
+
+[dependencies.fj]
+path = "../../fj"

crates/fj-app/model-template/README.md

@@ -0,0 +1,3 @@
+# Fornjot - Model Template
+
+This template is compiled into the `fj-app` binary, where it is used to generate new models.

crates/fj-app/model-template/src/lib.rs

@@ -0,0 +1,40 @@
+use std::f64::consts::PI;
+
+#[fj::model]
+pub fn model(
+    #[param(default = 5, min = 3)] num_points: u64,
+    #[param(default = 1.0, min = 1.0)] r1: f64,
+    #[param(default = 2.0, min = 2.0)] r2: f64,
+    #[param(default = 1.0)] h: f64,
+) -> fj::Shape {
+    let num_vertices = num_points * 2;
+    let vertex_iter = (0..num_vertices).map(|i| {
+        let angle =
+            fj::Angle::from_rad(2. * PI / num_vertices as f64 * i as f64);
+        let radius = if i % 2 == 0 { r1 } else { r2 };
+        (angle, radius)
+    });
+
+    // Now that we got that iterator prepared, generating the vertices is just a
+    // bit of trigonometry.
+    let mut outer = Vec::new();
+    let mut inner = Vec::new();
+    for (angle, radius) in vertex_iter {
+        let (sin, cos) = angle.rad().sin_cos();
+
+        let x = cos * radius;
+        let y = sin * radius;
+
+        outer.push([x, y]);
+        inner.push([x / 2., y / 2.]);
+    }
+
+    let outer = fj::Sketch::from_points(outer);
+    let inner = fj::Sketch::from_points(inner);
+
+    let footprint = fj::Difference2d::from_shapes([outer.into(), inner.into()]);
+
+    let star = fj::Sweep::from_path(footprint.into(), [0., 0., h]);
+
+    star.into()
+}

crates/fj-app/src/model_crate.rs

@@ -1,8 +1,6 @@
 use std::{fs, path::Path};
 use tar::Archive;
 
-static NEW_MODEL_TEMPLATE: &str = "star";
-
 static NEW_MODEL_TAR: &[u8] =
     include_bytes!(concat!(env!("OUT_DIR"), "/new_model.tar"));
 
@@ -22,11 +20,11 @@ fn postprocess_model_files(
         &path.join("Cargo.toml"),
         [
             (
-                format!("name = \"{NEW_MODEL_TEMPLATE}\""),
+                "name = \"model-template\"".to_string(),
                 format!("name = \"{model_name}\""),
             ),
             (
-                r#"path = "../../crates/fj""#.to_owned(),
+                r#"path = "../../fj""#.to_owned(),
                 ["version = \"", &fj::version::VERSION_PKG.to_string(), "\""]
                     .concat(),
             ),