diff --git a/shared/src/bxdfs/diffuse.rs b/shared/src/bxdfs/diffuse.rs
index 0643b4f..70e20a0 100644
--- a/shared/src/bxdfs/diffuse.rs
+++ b/shared/src/bxdfs/diffuse.rs
@@ -41,7 +41,7 @@ impl BxDFTrait for DiffuseBxDF {
             return None;
         }
         let mut wi = sample_cosine_hemisphere(u);
-        if wo.z() == 0. {
+        if wo.z() < 0. {
             wi[2] *= -1.;
         }
         let pdf = cosine_hemisphere_pdf(abs_cos_theta(wi));
diff --git a/shared/src/cameras/orthographic.rs b/shared/src/cameras/orthographic.rs
index 8a9ab3a..021d549 100644
--- a/shared/src/cameras/orthographic.rs
+++ b/shared/src/cameras/orthographic.rs
@@ -114,7 +114,7 @@ impl CameraTrait for OrthographicCamera {
 
         Some(CameraRay {
             ray: camera_ray,
-            weight: SampledSpectrum::default(),
+            weight: SampledSpectrum::new(1.),
         })
     }
 
diff --git a/shared/src/cameras/spherical.rs b/shared/src/cameras/spherical.rs
index 6caaf11..3400c6c 100644
--- a/shared/src/cameras/spherical.rs
+++ b/shared/src/cameras/spherical.rs
@@ -58,7 +58,7 @@ impl CameraTrait for SphericalCamera {
         );
         Some(CameraRay {
             ray: self.render_from_camera(&ray, &mut None),
-            weight: SampledSpectrum::default(),
+            weight: SampledSpectrum::new(1.),
         })
     }
 }
diff --git a/shared/src/core/bssrdf.rs b/shared/src/core/bssrdf.rs
index 6559eac..bccbed6 100644
--- a/shared/src/core/bssrdf.rs
+++ b/shared/src/core/bssrdf.rs
@@ -86,7 +86,7 @@ impl From<&SubsurfaceInteraction> for SurfaceInteraction {
             dvdx: 0.,
             dudy: 0.,
             dvdy: 0.,
-            shape: Ptr::from(&Shape::default()),
+            shape: Ptr::null(),
         }
     }
 }
diff --git a/shared/src/core/medium.rs b/shared/src/core/medium.rs
index bc9d18a..f9ab279 100644
--- a/shared/src/core/medium.rs
+++ b/shared/src/core/medium.rs
@@ -11,7 +11,7 @@ use crate::utils::containers::SampledGrid;
 use crate::utils::math::{clamp, square};
 use crate::utils::rng::Rng;
 use crate::utils::transform::Transform;
-use crate::{gvec_with_capacity, GVec, Ptr};
+use crate::{gvec_with_capacity, leak, GVec, Ptr};
 use enum_dispatch::enum_dispatch;
 use num_traits::Float as NumFloat;
 
@@ -170,7 +170,7 @@ pub struct RayMajorantSegment {
 }
 
 #[repr(C)]
-#[derive(Clone, Copy, Debug)]
+#[derive(Clone, Debug)]
 pub enum RayMajorantIterator {
     Homogeneous(HomogeneousMajorantIterator),
     DDA(DDAMajorantIterator),
@@ -191,7 +191,7 @@ impl Iterator for RayMajorantIterator {
 }
 
 #[repr(C)]
-#[derive(Clone, Copy, Debug)]
+#[derive(Clone, Debug)]
 pub struct HomogeneousMajorantIterator {
     called: bool,
     seg: RayMajorantSegment,
@@ -224,7 +224,7 @@ impl Iterator for HomogeneousMajorantIterator {
 }
 
 #[repr(C)]
-#[derive(Debug, Clone, Copy)]
+#[derive(Debug, Clone)]
 pub struct DDAMajorantIterator {
     sigma_t: SampledSpectrum,
     t_min: Float,
@@ -728,20 +728,20 @@ impl Default for MediumInterface {
 }
 
 impl From<Medium> for MediumInterface {
-    fn from(medium: Medium) -> Self {
+    fn from(p: Ptr<Medium>) -> Self {
         Self {
-            inside: Ptr::from(&medium),
-            outside: Ptr::from(&medium),
+            inside: p,
+            outside: p,
         }
     }
 }
 
-impl From<&Medium> for MediumInterface {
-    fn from(medium: &Medium) -> Self {
-        Self::from(medium.clone())
-    }
-}
-
+// impl From<&Medium> for MediumInterface {
+//     fn from(medium: &Medium) -> Self {
+//         Self::from(medium.clone())
+//     }
+// }
+//
 impl MediumInterface {
     pub fn new(inside: &Medium, outside: &Medium) -> Self {
         Self {
diff --git a/shared/src/shapes/cylinder.rs b/shared/src/shapes/cylinder.rs
index e15f8df..b064123 100644
--- a/shared/src/shapes/cylinder.rs
+++ b/shared/src/shapes/cylinder.rs
@@ -9,8 +9,8 @@ use crate::core::shape::{
 use crate::utils::splines::{
     bound_cubic_bezier, cubic_bezier_control_points, evaluate_cubic_bezier, subdivide_cubic_bezier,
 };
-use crate::utils::transform::{Transform, look_at};
-use crate::{Float, PI, gamma};
+use crate::utils::transform::{look_at, Transform};
+use crate::{gamma, Float, PI};
 
 use crate::core::geometry::{SqrtExt, Tuple};
 use crate::utils::interval::Interval;
@@ -61,11 +61,10 @@ impl CylinderShape {
         let di = self
             .object_from_render
             .apply_to_vector_interval(&Vector3fi::new_from_vector(r.d));
-        // Solve quadratic equation to find cylinder t0 and t1 values>>
-        let a: Interval = square(di.x()) + square(di.y()) + square(di.z());
-        let b: Interval = 2. * (di.x() * oi.x() + di.y() * oi.y() + di.z() * oi.z());
-        let c: Interval =
-            square(oi.x()) + square(oi.y()) + square(oi.z()) - square(Interval::new(self.radius));
+        // Solve quadratic equation to find cylinder t0 and t1 values
+        let a: Interval = square(di.x()) + square(di.y());
+        let b: Interval = 2. * (di.x() * oi.x() + di.y() * oi.y());
+        let c: Interval = square(oi.x()) + square(oi.y()) - square(Interval::new(self.radius));
         let f = b / (2. * a);
         let vx: Interval = oi.x() - f * di.x();
         let vy: Interval = oi.y() - f * di.y();
diff --git a/shared/src/shapes/sphere.rs b/shared/src/shapes/sphere.rs
index 21d156e..903620d 100644
--- a/shared/src/shapes/sphere.rs
+++ b/shared/src/shapes/sphere.rs
@@ -108,7 +108,7 @@ impl SphereShape {
             mem::swap(&mut t0, &mut t1);
         }
 
-        if t0.high > t_max || t1.low < 0. {
+        if t0.high >= t_max || t1.low <= 0. {
             return None;
         }
         let mut t_shape_hit = t0;