From 344df2c3d93258416747d6bdba75b9faa2981d70 Mon Sep 17 00:00:00 2001
From: Daniel Oom <daoo314@gmail.com>
Date: Sat, 26 Oct 2024 19:01:49 +0200
Subject: [PATCH] Implement sphere normal computation

---
 geometry/src/geometry.rs        | 12 ++++++++----
 geometry/src/sphere.rs          | 10 +++++++++-
 material-tester-cli/src/main.rs |  6 +++---
 3 files changed, 20 insertions(+), 8 deletions(-)

diff --git a/geometry/src/geometry.rs b/geometry/src/geometry.rs
index 52f6296..cb18ee0 100644
--- a/geometry/src/geometry.rs
+++ b/geometry/src/geometry.rs
@@ -83,7 +83,9 @@ pub enum GeometryProperties<M> {
         texcoords: TriangleTexcoords,
         material: M,
     },
-    Sphere(),
+    Sphere {
+        material: M,
+    },
 }
 
 impl<M> GeometryProperties<M> {
@@ -100,7 +102,7 @@ impl<M> GeometryProperties<M> {
                 texcoords: _,
                 material,
             } => material,
-            GeometryProperties::Sphere() => todo!(),
+            GeometryProperties::Sphere { material } => material,
         }
     }
 
@@ -117,7 +119,9 @@ impl<M> GeometryProperties<M> {
                 texcoords: _,
                 material: _,
             } => normals.lerp(u, v),
-            GeometryProperties::Sphere() => todo!(),
+            GeometryProperties::Sphere { material: _ } => {
+                Vec3::new(u.sin() * v.cos(), u.sin() * v.sin(), u.cos())
+            }
         }
     }
 
@@ -134,7 +138,7 @@ impl<M> GeometryProperties<M> {
                 texcoords,
                 material: _,
             } => texcoords.lerp(u, v),
-            GeometryProperties::Sphere() => todo!(),
+            GeometryProperties::Sphere { material: _ } => Vec2::new(u, v),
         }
     }
 }
diff --git a/geometry/src/sphere.rs b/geometry/src/sphere.rs
index 760def2..595036d 100644
--- a/geometry/src/sphere.rs
+++ b/geometry/src/sphere.rs
@@ -46,7 +46,15 @@ impl Sphere {
         let t1 = (-b - discriminant.sqrt()) / (2.0 * a);
         let t2 = (-b + discriminant.sqrt()) / (2.0 * a);
         let t = if t1 <= t2 { t1 } else { t2 };
-        Some(RayIntersection { t, u: 0.0, v: 0.0 })
+
+        let normal = ray.param(t) - self.center;
+        let theta = normal.x.atan2(normal.y);
+        let phi = (normal.z / self.radius).acos();
+        Some(RayIntersection {
+            t,
+            u: theta,
+            v: phi,
+        })
     }
 }
 
diff --git a/material-tester-cli/src/main.rs b/material-tester-cli/src/main.rs
index 0aaeafc..2a2dbe5 100644
--- a/material-tester-cli/src/main.rs
+++ b/material-tester-cli/src/main.rs
@@ -140,7 +140,7 @@ fn main() {
     );
     let pinhole = Pinhole::new(camera, args.size.as_uvec2());
     let geometries = vec![Sphere::new(Vec3::new(0.0, 0.0, 0.0), 1.0).into()];
-    let properties = vec![GeometryProperties::Sphere()];
+    let properties = vec![GeometryProperties::Sphere { material: 0 }];
     let materials = vec![Material {
         diffuse_reflectance: [1.0, 0.0, 0.0].into(),
         diffuse_texture_reflectance: None,
@@ -151,9 +151,9 @@ fn main() {
         transparency: 0.0,
     }];
     let lights = vec![SphericalLight {
-        center: [0.0, 0.0, 0.0].into(),
+        center: [-2.0, -2.0, -2.0].into(),
         intensity: [1.0, 1.0, 1.0].into(),
-        radius: 1.0,
+        radius: 2.0,
     }];
     let accelerator = NoAccelerator {};
     let pathtracer = Pathtracer {