From 87f62eedb09916954889f2fcc4ed278fa0f1f0da Mon Sep 17 00:00:00 2001
From: Matthew Gordon <matthew@gordon.earth>
Date: Sat, 12 Sep 2020 09:45:21 -0400
Subject: [PATCH] Add photon parameter to Material::sample(), other changes to
 integrate()

---
 src/integrators.rs                   | 74 +++++++++++++++-------------
 src/materials/mod.rs                 |  2 +-
 src/materials/reflective_material.rs |  2 +-
 3 files changed, 42 insertions(+), 36 deletions(-)

diff --git a/src/integrators.rs b/src/integrators.rs
index 49b5d6e..c37da97 100644
--- a/src/integrators.rs
+++ b/src/integrators.rs
@@ -55,35 +55,36 @@ impl Integrator for WhittedIntegrator {
                 }
             })
             .chain(
-                [info.material.sample(&(world_to_bsdf_space * info.retro))]
-                    .iter()
-                    .map(|direction| {
-                        let world_space_direction = bsdf_to_world_space * direction;
-                        match sampler.sample(
-                            &Ray::new(info.location, world_space_direction).bias(0.000_000_1),
-                        ) {
-                            Some(recursive_hit) => {
-                                if recursion_limit > 0 {
-                                    let photon = info.material.bsdf()(
-                                        &(world_to_bsdf_space * info.retro),
-                                        direction,
-                                        &self.integrate(
-                                            &sampler,
-                                            &recursive_hit,
-                                            &photon,
-                                            recursion_limit - 1,
-                                        ),
-                                    );
-                                    photon.scale_intensity(
-                                        world_space_direction.dot(&info.normal).abs(),
-                                    )
-                                } else {
-                                    photon.scale_intensity(0.0)
-                                }
+                [info
+                    .material
+                    .sample(&(world_to_bsdf_space * info.retro), &photon)]
+                .iter()
+                .map(|direction| {
+                    let world_space_direction = bsdf_to_world_space * direction;
+                    match sampler
+                        .sample(&Ray::new(info.location, world_space_direction).bias(0.000_000_1))
+                    {
+                        Some(recursive_hit) => {
+                            if recursion_limit > 0 {
+                                let photon = info.material.bsdf()(
+                                    &(world_to_bsdf_space * info.retro),
+                                    direction,
+                                    &self.integrate(
+                                        &sampler,
+                                        &recursive_hit,
+                                        &photon,
+                                        recursion_limit - 1,
+                                    ),
+                                );
+                                photon
+                                    .scale_intensity(world_space_direction.dot(&info.normal).abs())
+                            } else {
+                                photon.scale_intensity(0.0)
                             }
-                            None => photon.scale_intensity(0.0),
                         }
-                    }),
+                        None => photon.scale_intensity(0.0),
+                    }
+                }),
             )
             .fold(photon.clone(), |a, b| {
                 let mut result = a;
@@ -115,18 +116,23 @@ impl Integrator for SimpleRandomIntegrator {
         let bsdf_to_world_space = world_to_bsdf_space
             .try_inverse()
             .expect("Expected matrix to be invertable.");
-        let w_i = info.material.sample(&(world_to_bsdf_space * info.retro));
-        let world_space_w_i = bsdf_to_world_space * w_i;
+        let world_space_w_i = info.retro;
+        let w_i = world_to_bsdf_space * world_space_w_i;
+        let w_o = info.material.sample(&w_i, &photon);
+        let world_space_w_o = bsdf_to_world_space * w_o;
         info.material.bsdf()(
-            &(world_to_bsdf_space * info.retro),
-            &w_i,
-            &match sampler.sample(&Ray::new(info.location, world_space_w_i).bias(0.000_000_1)) {
-                None => photon.set_intensity(world_space_w_i.y()),
+            &w_o.normalize(),
+            &w_i.normalize(),
+            &match sampler.sample(&Ray::new(info.location, world_space_w_o).bias(0.000_000_1)) {
+                None => photon.set_intensity(test_lighting_environment(
+                    &world_space_w_o,
+                    photon.wavelength,
+                )),
                 Some(recursive_hit) => {
                     self.integrate(&sampler, &recursive_hit, &photon, recursion_limit - 1)
                 }
             }
-            .scale_intensity(world_space_w_i.dot(&info.normal).abs()),
+            .scale_intensity(world_space_w_o.dot(&info.normal).abs()),
         )
     }
 }
diff --git a/src/materials/mod.rs b/src/materials/mod.rs
index 8a170e4..fb2be32 100644
--- a/src/materials/mod.rs
+++ b/src/materials/mod.rs
@@ -18,7 +18,7 @@ pub use reflective_material::ReflectiveMaterial;
 pub trait Material: Debug + Sync + Send {
     fn bsdf<'a>(&'a self) -> Box<dyn Fn(&Vec3, &Vec3, &Photon) -> Photon + 'a>;
 
-    fn sample(&self, _w_i: &Vec3) -> Vec3 {
+    fn sample(&self, _w_i: &Vec3, _photon: &Photon) -> Vec3 {
         let mut rng = thread_rng();
         let mut w_o = Vec3::new(
             2.0 * rng.sample::<f64, _>(Open01) - 1.0,
diff --git a/src/materials/reflective_material.rs b/src/materials/reflective_material.rs
index 3446229..05ff4e9 100644
--- a/src/materials/reflective_material.rs
+++ b/src/materials/reflective_material.rs
@@ -39,7 +39,7 @@ impl Material for ReflectiveMaterial {
         })
     }
 
-    fn sample(&self, w_o: &Vec3) -> Vec3 {
+    fn sample(&self, w_o: &Vec3, _photon: &Photon) -> Vec3 {
         Vec3::new(-w_o.x(), -w_o.y(), w_o.z())
     }
 }