From 6ce7a8e3f9bf4296f5a87ad825e2b002409f9cd7 Mon Sep 17 00:00:00 2001
From: Robert Swain <robert.swain@gmail.com>
Date: Wed, 1 Feb 2023 20:09:23 +0100
Subject: [PATCH] bevy_pbr: Add cascade debug visualization

---
 crates/bevy_pbr/src/render/pbr_functions.wgsl |  5 ++++-
 crates/bevy_pbr/src/render/shadows.wgsl       | 19 ++++++++++++++++---
 2 files changed, 20 insertions(+), 4 deletions(-)

diff --git a/crates/bevy_pbr/src/render/pbr_functions.wgsl b/crates/bevy_pbr/src/render/pbr_functions.wgsl
index 57b516202..c33cea15b 100644
--- a/crates/bevy_pbr/src/render/pbr_functions.wgsl
+++ b/crates/bevy_pbr/src/render/pbr_functions.wgsl
@@ -226,7 +226,10 @@ fn pbr(
                 && (lights.directional_lights[i].flags & DIRECTIONAL_LIGHT_FLAGS_SHADOWS_ENABLED_BIT) != 0u) {
             shadow = fetch_directional_shadow(i, in.world_position, in.world_normal, view_z);
         }
-        let light_contrib = directional_light(i, roughness, NdotV, in.N, in.V, R, F0, diffuse_color);
+        var light_contrib = directional_light(i, roughness, NdotV, in.N, in.V, R, F0, diffuse_color);
+#ifdef DIRECTIONAL_LIGHT_SHADOW_MAP_DEBUG_CASCADES
+        light_contrib = cascade_debug_visualization(light_contrib, i, view_z);
+#endif
         light_accum = light_accum + light_contrib * shadow;
     }
 
diff --git a/crates/bevy_pbr/src/render/shadows.wgsl b/crates/bevy_pbr/src/render/shadows.wgsl
index a3f1f79a9..f74733c90 100644
--- a/crates/bevy_pbr/src/render/shadows.wgsl
+++ b/crates/bevy_pbr/src/render/shadows.wgsl
@@ -144,7 +144,7 @@ fn sample_cascade(light_id: u32, cascade_index: u32, frag_position: vec4<f32>, s
         directional_shadow_textures_sampler,
         light_local,
         depth
-    );   
+    );
 #else
     return textureSampleCompareLevel(
         directional_shadow_textures,
@@ -152,14 +152,14 @@ fn sample_cascade(light_id: u32, cascade_index: u32, frag_position: vec4<f32>, s
         light_local,
         i32((*light).depth_texture_base_index + cascade_index),
         depth
-    );   
+    );
 #endif
 }
 
 fn fetch_directional_shadow(light_id: u32, frag_position: vec4<f32>, surface_normal: vec3<f32>, view_z: f32) -> f32 {
     let light = &lights.directional_lights[light_id];
     let cascade_index = get_cascade_index(light_id, view_z);
-    
+
     if (cascade_index >= (*light).num_cascades) {
         return 1.0;
     }
@@ -178,3 +178,16 @@ fn fetch_directional_shadow(light_id: u32, frag_position: vec4<f32>, surface_nor
     }
     return shadow;
 }
+
+fn cascade_debug_visualization(
+    output_color: vec3<f32>,
+    light_id: u32,
+    view_z: f32,
+) -> vec3<f32> {
+    let overlay_alpha = 0.95;
+    let cascade_index = get_cascade_index(light_id, view_z);
+    let cascade_color = hsv2rgb(f32(cascade_index) / f32(#{MAX_CASCADES_PER_LIGHT}u + 1u), 1.0, 0.5);
+    return vec3<f32>(
+        (1.0 - overlay_alpha) * output_color.rgb + overlay_alpha * cascade_color
+    );
+}
-- 
2.39.1