ft (wip): textures

src/objects/sphere.rs

@@ -1,4 +1,5 @@
 use core::f32::math::sqrt;
+use std::f32::consts::PI;
 use std::fmt::{self, Debug};
 use std::sync::Arc;
 
@@ -14,7 +15,6 @@ pub struct Sphere {
     material: Arc<dyn Material>,
 }
 
-
 impl Debug for Sphere {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         f.debug_struct("Sphere")
@@ -59,13 +59,26 @@ impl Hittable for Sphere {
             let t = if tl > 0.001 { tl } else { tr };
             let p = r.at(t);
             let out_n = (p - self.center) / self.radius;
+            let uv = self.to_uv(&p);
             Some(Hit::new(
                 t,
                 p,
                 (p - self.center).get_unit(),
                 self.material.clone(),
                 out_n.dot(r.dir()) < 0.,
+                *uv.x(),
+                *uv.y(),
             ))
         }
     }
+
+    fn to_uv(&self, point: &Vec3) -> Vec3 {
+        let p = *point - self.center;
+        // TODO: add rotated texture support
+        return Vec3::new(
+            0.5 + p.y().atan2(*p.x()) / (2. * PI),
+            1. - (p.z() / self.radius).acos() / PI,
+            0.0,
+        );
+    }
 }