From 829476c602bba7e76e261751f0b6a539830b9bab Mon Sep 17 00:00:00 2001
From: hal8174 <henning.lindemann@pm.me>
Date: Tue, 31 Dec 2024 18:04:52 +0100
Subject: [PATCH] Add albedo to material visualization

---
 ray-tracing-core/src/color.rs                 |  6 +++
 ray-tracing-material-visualizer/src/main.rs   | 44 +++++++++++++++----
 .../src/examples/stanford_dragon.rs           |  8 +---
 3 files changed, 43 insertions(+), 15 deletions(-)

diff --git a/ray-tracing-core/src/color.rs b/ray-tracing-core/src/color.rs
index 3756b77..8e52159 100644
--- a/ray-tracing-core/src/color.rs
+++ b/ray-tracing-core/src/color.rs
@@ -101,3 +101,9 @@ impl Mul<Color> for Float {
         Color::new(self * rhs.r, self * rhs.g, self * rhs.b)
     }
 }
+
+impl std::iter::Sum for Color {
+    fn sum<I: Iterator<Item = Self>>(iter: I) -> Self {
+        iter.reduce(|a, b| a + b).unwrap_or(Color::black())
+    }
+}
diff --git a/ray-tracing-material-visualizer/src/main.rs b/ray-tracing-material-visualizer/src/main.rs
index 2dbd129..d536963 100644
--- a/ray-tracing-material-visualizer/src/main.rs
+++ b/ray-tracing-material-visualizer/src/main.rs
@@ -14,24 +14,26 @@ use ray_tracing_material::{
     mirror::Mirror,
     oren_nayar::OrenNayar,
 };
-use rayon::iter::{IntoParallelIterator, ParallelExtend, ParallelIterator};
+use rayon::iter::{
+    IntoParallelIterator, IntoParallelRefIterator, ParallelExtend, ParallelIterator,
+};
 
 fn main() -> Result<(), Box<dyn std::error::Error>> {
     let w_in = Dir3::new(1.0, 1.0, 0.0).normalize();
 
     let color = Color::new(1.0, 1.0, 1.0);
 
-    // let m = Mirror::new(color);
-    // generate_chart("mirror.png", &m, 2, w_in)?;
+    let m = Mirror::new(color);
+    generate_chart("mirror.png", &m, 2, w_in)?;
 
-    // let m = DiffuseMaterial::new(color);
-    // generate_chart("diffuse.png", &m, 100, w_in)?;
+    let m = DiffuseMaterial::new(color);
+    generate_chart("diffuse.png", &m, 100, w_in)?;
 
     let m = Microfacet::new(BeckmannDistribution::new(0.1), color);
     generate_chart("microfacet.png", &m, 100, w_in)?;
 
-    // let m = OrenNayar::new(0.5, color);
-    // generate_chart("oren-nayar.png", &m, 100, w_in)?;
+    let m = OrenNayar::new(0.5, color);
+    generate_chart("oren-nayar.png", &m, 100, w_in)?;
 
     Ok(())
 }
@@ -59,10 +61,28 @@ fn generate_chart<M: Material<SmallRng>>(
         Float::MIN_POSITIVE,
     );
 
-    let area = areas[0].titled("Evaled", ("sans-serif", 30))?;
+    let eval_energy = eval_histogram.energy();
+    let area = areas[0].titled(
+        &format!(
+            "Evaled ({:.4}, {:.4}, {:.4})",
+            eval_energy.r(),
+            eval_energy.g(),
+            eval_energy.b()
+        ),
+        ("sans-serif", 30),
+    )?;
     plot_material(&area, eval_histogram, max)?;
 
-    let area = areas[1].titled("Sampled", ("sans-serif", 30))?;
+    let sample_energy = sample_histogram.energy();
+    let area = areas[1].titled(
+        &format!(
+            "Evaled ({:.4}, {:.4}, {:.4})",
+            sample_energy.r(),
+            sample_energy.g(),
+            sample_energy.b()
+        ),
+        ("sans-serif", 30),
+    )?;
     plot_material(&area, sample_histogram, max)?;
 
     root.present()?;
@@ -240,6 +260,12 @@ impl Histogram {
             })
             .filter(|(dir, _)| dir.x() * dir.x() + dir.z() * dir.z() < 1.0)
     }
+
+    fn energy(&self) -> Color {
+        let total = self.data.par_iter().copied().sum::<Color>();
+
+        total / (self.inserted as Float)
+    }
 }
 
 impl ParallelExtend<(Dir3, Color)> for Histogram {
diff --git a/ray-tracing-scene/src/examples/stanford_dragon.rs b/ray-tracing-scene/src/examples/stanford_dragon.rs
index d49b237..f7cee2c 100644
--- a/ray-tracing-scene/src/examples/stanford_dragon.rs
+++ b/ray-tracing-scene/src/examples/stanford_dragon.rs
@@ -16,11 +16,6 @@ use super::ExampleScene;
 
 pub fn scene<R: Rng + Debug + 'static>() -> ExampleScene<R> {
     let f = || {
-        let color = Color::new(0.2, 0.2, 0.9);
-        // let m = DiffuseMaterial::new(color);
-        let m = Microfacet::new(BeckmannDistribution::new(0.1), color);
-        // let m = OrenNayar::new(0.5, color);
-
         let obj = ObjData::new("ray-tracing-scene/obj/stanford_dragon.obj").unwrap();
 
         let mut triangles = obj
@@ -28,8 +23,9 @@ pub fn scene<R: Rng + Debug + 'static>() -> ExampleScene<R> {
             .map(|t| Triangle::new(t.v, 0))
             .collect::<Vec<_>>();
 
+        let color = Color::new(0.2, 0.2, 0.9);
         let materials = vec![
-            BVHMaterial::new_material(m),
+            BVHMaterial::new_material(Microfacet::new(BeckmannDistribution::new(0.01), color)),
             BVHMaterial::new_material(OrenNayar::new(0.5, Color::new(0.8, 0.8, 0.8))),
             BVHMaterial::new_material(OrenNayar::new(0.5, Color::new(0.9, 0.0, 0.0))),
             BVHMaterial::new_material(OrenNayar::new(0.5, Color::new(0.0, 0.9, 0.0))),