Fix directional light shadow frustum culling near clip plane to infinity (#12342)

# Objective

- Fix slightly wrong logic from #11442
- Directional lights should not have a near clip plane

## Solution

- Push near clip out to infinity, so that the frustum normal is still
available if its needed for whatever reason in shader
- also opportunistically nabs a typo

crates/bevy_pbr/src/light.rs

@@ -589,7 +589,7 @@ fn calculate_cascade(
 
     // It is critical for `world_to_cascade` to be stable. So rather than forming `cascade_to_world`
     // and inverting it, which risks instability due to numerical precision, we directly form
-    // `world_to_cascde` as the reference material suggests.
+    // `world_to_cascade` as the reference material suggests.
     let light_to_world_transpose = light_to_world.transpose();
     let world_to_cascade = Mat4::from_cols(
         light_to_world_transpose.x_axis,

crates/bevy_pbr/src/render/light.rs

@@ -5,7 +5,7 @@ use bevy_math::{Mat4, UVec3, UVec4, Vec2, Vec3, Vec3Swizzles, Vec4, Vec4Swizzles
 use bevy_render::{
     camera::Camera,
     mesh::Mesh,
-    primitives::{CascadesFrusta, CubemapFrusta, Frustum},
+    primitives::{CascadesFrusta, CubemapFrusta, Frustum, HalfSpace},
     render_asset::RenderAssets,
     render_graph::{Node, NodeRunError, RenderGraphContext},
     render_phase::*,
@@ -1144,7 +1144,7 @@ pub fn prepare_lights(
                 .unwrap()
                 .iter()
                 .take(MAX_CASCADES_PER_LIGHT);
-            for (cascade_index, ((cascade, frusta), bound)) in cascades
+            for (cascade_index, ((cascade, frustum), bound)) in cascades
                 .zip(frusta)
                 .zip(&light.cascade_shadow_config.bounds)
                 .enumerate()
@@ -1171,6 +1171,11 @@ pub fn prepare_lights(
                         });
                 directional_depth_texture_array_index += 1;
 
+                let mut frustum = *frustum;
+                // Push the near clip plane out to infinity for directional lights
+                frustum.half_spaces[4] =
+                    HalfSpace::new(frustum.half_spaces[4].normal().extend(f32::INFINITY));
+
                 let view_light_entity = commands
                     .spawn((
                         ShadowView {
@@ -1191,7 +1196,7 @@ pub fn prepare_lights(
                             hdr: false,
                             color_grading: Default::default(),
                         },
-                       *frusta,
+                        frustum,
                         RenderPhase::<Shadow>::default(),
                         LightEntity::Directional {
                             light_entity,