From 30322d639f3a36200e3481eb65ddefc9558e443c Mon Sep 17 00:00:00 2001
From: Yeicor <4929005+Yeicor@users.noreply.github.com>
Date: Wed, 24 Aug 2022 20:31:23 +0200
Subject: [PATCH] Cleaner FFI API

---
 README.md           |  8 ++++----
 src/sdf/demo/ffi.rs |  8 ++++++++
 src/sdf/demo/mod.rs |  2 ++
 src/sdf/ffi.rs      | 10 ++--------
 4 files changed, 16 insertions(+), 12 deletions(-)
 create mode 100644 src/sdf/demo/ffi.rs

diff --git a/README.md b/README.md
index 80fdd5d..b5ba402 100644
--- a/README.md
+++ b/README.md
@@ -117,10 +117,10 @@ SDF), and you should keep the source code or the wasm file in order to export hi
 
 ## Integrations
 
-| Repo                                                      | Language | Library                                                                                                               | Features                          | Notes                                                                                                     |
-|:----------------------------------------------------------|----------|-----------------------------------------------------------------------------------------------------------------------|-----------------------------------|-----------------------------------------------------------------------------------------------------------|
-| [sdf-viewer](https://github.com/Yeicor/sdf-viewer/)       | Rust     | [Pure Rust](src/sdf/mod.rs)                                                                                           | Core<br/>Hierarchy<br/>Parameters | Used for the demo / feature showcase<br/>Also available as a library, see `sdf-viewer-rs-py`              |
-| [sdf-viewer-go](https://github.com/Yeicor/sdf-viewer-go/) | Go       | [Pure Go](https://github.com/Yeicor/sdf-viewer-go/tree/main/sdf-viewer-go)<br/>[SDFX](https://github.com/deadsy/sdfx) | Core<br/>Hierarchy<br/>Parameters | May be used as a guide for implementing your own<br/>integration due to the simplicity of the Go language |
+| Repo                                                      | Language | Library                                                                                                               | Features                          | Notes                                                                                                            |
+|:----------------------------------------------------------|----------|-----------------------------------------------------------------------------------------------------------------------|-----------------------------------|------------------------------------------------------------------------------------------------------------------|
+| [sdf-viewer](https://github.com/Yeicor/sdf-viewer/)       | Rust     | [Pure Rust](src/sdf/mod.rs)                                                                                           | Core<br/>Hierarchy<br/>Parameters | Used for the demo / feature showcase<br/>Available as a library (`sdfffi` feature, [usage](src/sdf/demo/ffi.rs)) |
+| [sdf-viewer-go](https://github.com/Yeicor/sdf-viewer-go/) | Go       | [Pure Go](https://github.com/Yeicor/sdf-viewer-go/tree/main/sdf-viewer-go)<br/>[SDFX](https://github.com/deadsy/sdfx) | Core<br/>Hierarchy<br/>Parameters | May be used as a guide for implementing your own<br/>integration due to the simplicity of the Go language        |
 
 **Feel free to create integrations for other languages and frameworks and add them to this list!**
 
diff --git a/src/sdf/demo/ffi.rs b/src/sdf/demo/ffi.rs
new file mode 100644
index 0000000..ebcb0f8
--- /dev/null
+++ b/src/sdf/demo/ffi.rs
@@ -0,0 +1,8 @@
+use crate::sdf::demo::SDFDemo;
+use crate::sdf::ffi::set_root_sdf;
+
+/// Entrypoint: only needs to set the root SDFSurface implementation.
+#[no_mangle]
+pub extern "C" fn init() {
+    set_root_sdf(Box::new(SDFDemo::default()));
+}
\ No newline at end of file
diff --git a/src/sdf/demo/mod.rs b/src/sdf/demo/mod.rs
index 56c6c8d..00bee49 100644
--- a/src/sdf/demo/mod.rs
+++ b/src/sdf/demo/mod.rs
@@ -13,6 +13,8 @@ use crate::sdf::demo::sphere::SDFDemoSphere;
 
 pub mod cube;
 pub mod sphere;
+#[cfg(feature = "sdfdemoffi")]
+pub mod ffi;
 
 /// An embedded demo `Sdf` implementation to showcase/test most features. Subtracts a cube and a sphere.
 #[derive(clap::Parser, Debug, Clone, PartialEq, Eq)]
diff --git a/src/sdf/ffi.rs b/src/sdf/ffi.rs
index 73fb74b..bb19b21 100644
--- a/src/sdf/ffi.rs
+++ b/src/sdf/ffi.rs
@@ -1,5 +1,7 @@
 //! This provides a external API for the SDF library. It matches the WebAssembly specification
 //! defined at [crate::sdf::wasm].
+//!
+//! See [crate::sdf::demo::ffi::init] for a usage example.
 
 use std::cell::RefCell;
 use std::collections::HashMap;
@@ -38,14 +40,6 @@ fn sdf_registry<R>(f: impl FnOnce(&HashMap<u32, Box<dyn SDFSurface>>) -> R) -> R
     })
 }
 
-/// Start entrypoint for building the demo SDF wasm.
-/// This contains all the boilerplate that users of the library would need to include in their code.
-#[cfg(feature = "sdfdemoffi")]
-#[no_mangle]
-pub extern "C" fn init() {
-    set_root_sdf(Box::new(SDFDemo::default()));
-}
-
 #[no_mangle]
 pub extern "C" fn bounding_box(sdf_id: u32) -> Box<[Vector3<f32>; 2]> {
     Box::new(sdf_registry(|r| r.get(&sdf_id)