Optimize GenericMaterial layout

Shaving off 2 floats, i.e. 16 bytes. Brings a 3-4% overall perf
increase. Should be possible to shave another 16 bytes.

examples/toroid25d.rs

@@ -100,7 +100,7 @@ fn main() {
                     let d = Vec2::new(to_m(x_px), to_m(y_px)) - center;
                     let r = d.mag();
                     if (conductor_inner_rad as _..conductor_outer_rad as _).contains(&r) {
-                        *driver.state.get_mut(loc).mat_mut() = mat::Static::conductor(conductivity).into();
+                        *driver.state.get_mut(loc).mat_mut() = mat::db::conductor(conductivity).into();
                     } else if (ferro_inner_rad as _..ferro_outer_rad as _).contains(&r) {
                         let half_depth_px = from_m(half_depth);
                         let ferro_depth_px = from_m(ferro_depth);

examples/wrapped_torus.rs

@@ -28,14 +28,14 @@ fn main() {
     let size_px = Index((width_px, width_px, depth_px).into());
     let mut driver = Driver::new(size_px, feat_size);
     driver.set_steps_per_frame(1000);
-    let base = "wrapped_torus-11";
+    let base = "wrapped_torus-12";
     let ferro_region = Torus::new_xy(Meters((half_width, half_width, half_depth).into()), ferro_major, ferro_minor);
     let drive_region = Torus::new_xz(Meters((half_width - ferro_major, half_width, half_depth).into()), wire_major, wire_minor);
     let sense_region = Torus::new_xz(Meters((half_width + ferro_major, half_width, half_depth).into()), wire_major, wire_minor);
 
     driver.fill_region(&ferro_region, mat::db::ferroxcube_3r1());
-    driver.fill_region(&drive_region, mat::Static::conductor(conductivity).into());
-    driver.fill_region(&sense_region, mat::Static::conductor(conductivity).into());
+    driver.fill_region(&drive_region, mat::db::conductor(conductivity).into());
+    driver.fill_region(&sense_region, mat::db::conductor(conductivity).into());
 
     let boundary_xy = half_width - ferro_major - ferro_minor - buffer;
     let boundary_z = half_depth - wire_major - wire_minor - buffer;

src/driver.rs

@@ -181,7 +181,7 @@ impl<M: Material + Clone + Default + Send + Sync + 'static> Driver<M> {
     }
 }
 
-impl<M: Material + From<mat::Static>> Driver<M> {
+impl<M: Material + From<mat::Conductor>> Driver<M> {
     // pub fn add_boundary(&mut self, thickness: u32, base_conductivity: Flt) {
     //     for inset in 0..thickness {
     //         let depth = thickness - inset;
@@ -252,7 +252,7 @@ impl<M: Material + From<mat::Static>> Driver<M> {
                         };
                         let cond = Vec3::new(cond_x, cond_y, cond_z);
                         // trace!("cond: {:?}", cond);
-                        let conductor = mat::Static::anisotropic_conductor(cond);
+                        let conductor = mat::db::anisotropic_conductor(cond);
                         *self.state.get_mut(Index(Vec3u::new(x, y, z))).mat_mut() = conductor.into();
                     }
                 }

src/mat.rs

@@ -29,24 +29,37 @@ pub trait Material {
     }
 }
 
+/// Materical which has a conductivity parameter, but cannot be magnetized
+#[derive(Clone, Default, Serialize, Deserialize)]
+pub struct Conductor {
+    conductivity: Vec3,
+}
+
+impl Conductor {
+    pub fn new(conductivity: Flt) -> Self {
+        Self::new_anisotropic(Vec3::unit() * conductivity)
+    }
+    pub fn new_anisotropic(conductivity: Vec3) -> Self {
+        Self {
+            conductivity,
+        }
+    }
+}
+
+impl Material for Conductor {
+    fn conductivity(&self) -> Vec3 {
+        self.conductivity
+    }
+}
+
+/// Capable of capturing all field-related information about a material at any
+/// snapshot moment-in-time. Useful for serializing state.
 #[derive(Clone, Default, Serialize, Deserialize)]
 pub struct Static {
     pub conductivity: Vec3,
     pub m: Vec3,
 }
 
-impl Static {
-    pub fn conductor(conductivity: Flt) -> Self {
-        Self::anisotropic_conductor(Vec3::unit() * conductivity)
-    }
-    pub fn anisotropic_conductor(conductivity: Vec3) -> Self {
-        Self {
-            conductivity,
-            ..Default::default()
-        }
-    }
-}
-
 impl Material for Static {
     fn conductivity(&self) -> Vec3 {
         self.conductivity
@@ -162,7 +175,7 @@ impl MHCurve {
 pub struct PiecewiseLinearFerromagnet {
     /// Instantaneous magnetization in the z direction.
     pub m: Vec3,
-    pub conductivity: Vec3,
+    pub conductivity: Flt,
     mh_curve: &'static MHCurve,
 }
 
@@ -184,7 +197,7 @@ impl Material for PiecewiseLinearFerromagnet {
         self.m
     }
     fn conductivity(&self) -> Vec3 {
-        self.conductivity
+        Vec3::new(self.conductivity, self.conductivity, self.conductivity)
     }
     fn step_h(&mut self, context: &CellState, delta_b: Vec3) -> Vec3 {
         trace!("step_h enter");
@@ -206,20 +219,26 @@ impl Material for PiecewiseLinearFerromagnet {
 #[enum_dispatch(Material)]
 #[derive(Clone)]
 pub enum GenericMaterial {
-    Static(Static),
+    Conductor(Conductor),
     // ComsolFerromagnet(ComsolFerromagnet),
     PiecewiseLinearFerromagnet(PiecewiseLinearFerromagnet)
 }
 
 impl Default for GenericMaterial {
     fn default() -> Self {
-        Static::default().into()
+        Conductor::default().into()
     }
 }
 
 /// Database of common materials
 pub mod db {
     use super::*;
+    pub fn conductor(conductivity: Flt) -> Conductor {
+        Conductor::new(conductivity)
+    }
+    pub fn anisotropic_conductor(conductivity: Vec3) -> Conductor {
+        Conductor::new_anisotropic(conductivity)
+    }
     /// https://www.ferroxcube.com/upload/media/product/file/MDS/3r1.pdf
     pub fn ferroxcube_3r1() -> GenericMaterial {
         ferroxcube_3r1_concrete().into()
@@ -243,7 +262,7 @@ pub mod db {
     }
     pub fn ferroxcube_3r1_concrete() -> PiecewiseLinearFerromagnet {
         let mut m = PiecewiseLinearFerromagnet::new(ferroxcube_3r1_curve());
-        m.conductivity = Vec3::unit() * 1e-3;
+        m.conductivity = 1e-3;
         m
     }
 }