Add Context abstraction

Former-commit-id: 7bd77bfa85539326f688ead84edaf086c5c88985

mikktspace-sys/src/lib.rs

@@ -4,6 +4,7 @@ mod ffi;
 use std::os::raw::*;
 use std::mem;
 
+/// Rust FFI for the MikkTSpace implementation.
 const INTERFACE: ffi::SMikkTSpaceInterface = ffi::SMikkTSpaceInterface {
     m_getNumFaces: faces,
     m_getNumVerticesOfFace: vertices,
@@ -15,7 +16,26 @@ const INTERFACE: ffi::SMikkTSpaceInterface = ffi::SMikkTSpaceInterface {
 };
 
 pub struct Context {
-    faces: i32,
+    faces: Box<ExactSizeIterator<Item = Face>>,
+    positions: Box<ExactSizeIterator<Item = [f32; 3]>>,
+    tex_coords: Box<ExactSizeIterator<Item = [f32; 2]>>,
+    normals: Box<ExactSizeIterator<Item = [f32; 3]>>,
+}
+
+/// Specifies whether a face is a triangle or a quad.
+pub enum Face {
+    Triangle,
+    Quad,
+}
+
+impl Face {
+    /// Returns the number of vertices bound by this face.
+    pub fn vertices(&self) -> i32 {
+        match self {
+            &Face::Triangle { .. } => 3,
+            &Face::Quad { .. } => 4,
+        }
+    }
 }
 
 /// Returns the number of faces (triangles/quads) on the mesh to be processed.
@@ -23,7 +43,7 @@ pub struct Context {
 extern "C" fn faces(pContext: *const ffi::SMikkTSpaceContext) -> c_int {
     unsafe {
         let m: *const Context = mem::transmute(pContext);
-        (*m).faces as c_int
+        (*m).faces.len() as c_int
     }
 }
 
@@ -36,7 +56,7 @@ extern "C" fn vertices(
 ) -> c_int {
     unsafe {
         let _: *const Context = mem::transmute(pContext);
-        unimplemented!()
+        3
     }
 }
 
@@ -114,16 +134,19 @@ extern "C" fn set_tspace(
 }
 
 impl Context {
-    pub fn new() -> Self {
+    /// Constructor for a MikkTSpace `Context`.
+    pub fn new<F, P, T, N>(faces: F, positions: P, tex_coords: T, normals: N) -> Self
+    where
+        F: 'static + ExactSizeIterator<Item = Face>,
+        P: 'static + ExactSizeIterator<Item = [f32; 3]>,
+        T: 'static + ExactSizeIterator<Item = [f32; 2]>,
+        N: 'static + ExactSizeIterator<Item = [f32; 3]>,
+    {
         Context {
-            faces: 3,
+            faces: Box::new(faces),
+            positions: Box::new(positions),
+            tex_coords: Box::new(tex_coords),
+            normals: Box::new(normals),
         }
     }
 }
-
-#[cfg(test)]
-mod tests {
-    #[test]
-    fn it_works() {
-    }
-}