rtiow: add simple debugging material.

rtiow/renderer/src/material.rs

@@ -251,6 +251,20 @@ where
     }
 }
 
+#[derive(Debug)]
+pub struct DebugMaterial {}
+
+impl Material for DebugMaterial {
+    fn scatter(&self, _r_in: &Ray, rec: &HitRecord) -> ScatterResponse {
+        let dir = Vec3::new(0., -1., -1.).unit_vector();
+        ScatterResponse {
+            scattered: Ray::new(rec.p, dir, 0.),
+            attenutation: [1., 1., 1.].into(),
+            reflected: true,
+        }
+    }
+}
+
 #[cfg(test)]
 mod tests {
     use super::*;