Place percentage-closer soft shadows behind a feature gate to save on

samplers.

The two additional linear texture samplers that PCSS added caused us to
blow past the limit on Apple Silicon macOS and WebGL. To fix the issue,
this commit adds a `--feature pbr_pcss` feature gate that disables PCSS
if not present.

Closes bevyengine#15345.
Closes bevyengine#15525.
Closes bevyengine#15821.

Cargo.toml

@@ -402,6 +402,9 @@ pbr_multi_layer_material_textures = [
 # Enable support for anisotropy texture in the `StandardMaterial`, at the risk of blowing past the global, per-shader texture limit on older/lower-end GPUs
 pbr_anisotropy_texture = ["bevy_internal/pbr_anisotropy_texture"]
 
+# Enable support for PCSS, at the risk of blowing past the global, per-shader sampler limit on older/lower-end GPUs
+pbr_pcss = ["bevy_internal/pbr_pcss"]
+
 # Enable some limitations to be able to use WebGL2. Please refer to the [WebGL2 and WebGPU](https://github.com/bevyengine/bevy/tree/latest/examples#webgl2-and-webgpu) section of the examples README for more information on how to run Wasm builds with WebGPU.
 webgl2 = ["bevy_internal/webgl"]
 
@@ -3786,6 +3789,7 @@ wasm = true
 name = "pcss"
 path = "examples/3d/pcss.rs"
 doc-scrape-examples = true
+required-features = ["pbr_pcss"]
 
 [package.metadata.example.pcss]
 name = "Percentage-closer soft shadows"

crates/bevy_internal/Cargo.toml

@@ -134,6 +134,11 @@ pbr_anisotropy_texture = [
   "bevy_gltf?/pbr_anisotropy_texture",
 ]
 
+# Percentage-closer soft shadows
+pbr_pcss = [
+  "bevy_pbr?/pbr_pcss",
+]
+
 # Optimise for WebGL2
 webgl = [
   "bevy_core_pipeline?/webgl",

crates/bevy_pbr/Cargo.toml

@@ -14,6 +14,7 @@ webgpu = []
 pbr_transmission_textures = []
 pbr_multi_layer_material_textures = []
 pbr_anisotropy_texture = []
+pbr_pcss = []
 shader_format_glsl = ["bevy_render/shader_format_glsl"]
 trace = ["bevy_render/trace"]
 ios_simulator = ["bevy_render/ios_simulator"]

crates/bevy_pbr/src/render/light.rs

@@ -147,8 +147,10 @@ pub const MAX_CASCADES_PER_LIGHT: usize = 1;
 #[derive(Resource, Clone)]
 pub struct ShadowSamplers {
     pub point_light_comparison_sampler: Sampler,
+    #[cfg(feature = "pbr_pcss")]
     pub point_light_linear_sampler: Sampler,
     pub directional_light_comparison_sampler: Sampler,
+    #[cfg(feature = "pbr_pcss")]
     pub directional_light_linear_sampler: Sampler,
 }
 
@@ -172,13 +174,15 @@ impl FromWorld for ShadowSamplers {
                 compare: Some(CompareFunction::GreaterEqual),
                 ..base_sampler_descriptor
             }),
+            #[cfg(feature = "pbr_pcss")]
             point_light_linear_sampler: render_device.create_sampler(&base_sampler_descriptor),
             directional_light_comparison_sampler: render_device.create_sampler(
                 &SamplerDescriptor {
                     compare: Some(CompareFunction::GreaterEqual),
                     ..base_sampler_descriptor
                 },
             ),
+            #[cfg(feature = "pbr_pcss")]
             directional_light_linear_sampler: render_device
                 .create_sampler(&base_sampler_descriptor),
         }

crates/bevy_pbr/src/render/mesh.rs

@@ -1858,6 +1858,9 @@ impl SpecializedMeshPipeline for MeshPipeline {
         #[cfg(all(feature = "webgl", target_arch = "wasm32", not(feature = "webgpu")))]
         shader_defs.push("WEBGL2".into());
 
+        #[cfg(feature = "pbr_pcss")]
+        shader_defs.push("PCSS_SAMPLERS_AVAILABLE".into());
+
         if key.contains(MeshPipelineKey::TONEMAP_IN_SHADER) {
             shader_defs.push("TONEMAP_IN_SHADER".into());
             shader_defs.push(ShaderDefVal::UInt(

crates/bevy_pbr/src/render/mesh_view_bindings.rs

@@ -227,6 +227,7 @@ fn layout_entries(
             // Point Shadow Texture Array Comparison Sampler
             (3, sampler(SamplerBindingType::Comparison)),
             // Point Shadow Texture Array Linear Sampler
+            #[cfg(feature = "pbr_pcss")]
             (4, sampler(SamplerBindingType::Filtering)),
             // Directional Shadow Texture Array
             (
@@ -243,6 +244,7 @@ fn layout_entries(
             // Directional Shadow Texture Array Comparison Sampler
             (6, sampler(SamplerBindingType::Comparison)),
             // Directional Shadow Texture Array Linear Sampler
+            #[cfg(feature = "pbr_pcss")]
             (7, sampler(SamplerBindingType::Filtering)),
             // PointLights
             (
@@ -574,9 +576,11 @@ pub fn prepare_mesh_view_bind_groups(
                 (1, light_binding.clone()),
                 (2, &shadow_bindings.point_light_depth_texture_view),
                 (3, &shadow_samplers.point_light_comparison_sampler),
+                #[cfg(feature = "pbr_pcss")]
                 (4, &shadow_samplers.point_light_linear_sampler),
                 (5, &shadow_bindings.directional_light_depth_texture_view),
                 (6, &shadow_samplers.directional_light_comparison_sampler),
+                #[cfg(feature = "pbr_pcss")]
                 (7, &shadow_samplers.directional_light_linear_sampler),
                 (8, clusterable_objects_binding.clone()),
                 (

crates/bevy_pbr/src/render/mesh_view_bindings.wgsl

@@ -14,14 +14,18 @@
 @group(0) @binding(2) var point_shadow_textures: texture_depth_cube_array;
 #endif
 @group(0) @binding(3) var point_shadow_textures_comparison_sampler: sampler_comparison;
+#ifdef PCSS_SAMPLERS_AVAILABLE
 @group(0) @binding(4) var point_shadow_textures_linear_sampler: sampler;
+#endif  // PCSS_SAMPLERS_AVAILABLE
 #ifdef NO_ARRAY_TEXTURES_SUPPORT
 @group(0) @binding(5) var directional_shadow_textures: texture_depth_2d;
 #else
 @group(0) @binding(5) var directional_shadow_textures: texture_depth_2d_array;
 #endif
 @group(0) @binding(6) var directional_shadow_textures_comparison_sampler: sampler_comparison;
+#ifdef PCSS_SAMPLERS_AVAILABLE
 @group(0) @binding(7) var directional_shadow_textures_linear_sampler: sampler;
+#endif  // PCSS_SAMPLERS_AVAILABLE
 
 #if AVAILABLE_STORAGE_BUFFER_BINDINGS >= 3
 @group(0) @binding(8) var<storage> clusterable_objects: types::ClusterableObjects;

crates/bevy_pbr/src/render/shadow_sampling.wgsl

@@ -40,6 +40,8 @@ fn search_for_blockers_in_shadow_map_hardware(
     return vec2(0.0);
 #else   // WEBGL2
 
+#ifdef PCSS_SAMPLERS_AVAILABLE
+
 #ifdef NO_ARRAY_TEXTURES_SUPPORT
     let sampled_depth = textureSampleLevel(
         view_bindings::directional_shadow_textures,
@@ -58,6 +60,10 @@ fn search_for_blockers_in_shadow_map_hardware(
 #endif  // NO_ARRAY_TEXTURES_SUPPORT
     return select(vec2(0.0), vec2(sampled_depth, 1.0), sampled_depth >= depth);
 
+#else   // PCSS_SAMPLERS_AVAILABLE
+    return vec2(0.0);
+#endif  // PCSS_SAMPLERS_AVAILABLE
+
 #endif  // WEBGL2
 }
 
@@ -340,6 +346,8 @@ fn search_for_blockers_in_shadow_cubemap_hardware(
     return vec2(0.0);
 #else   // WEBGL2
 
+#ifdef PCSS_SAMPLERS_AVAILABLE
+
 #ifdef NO_CUBE_ARRAY_TEXTURES_SUPPORT
     let sampled_depth = textureSample(
         view_bindings::point_shadow_textures,
@@ -357,6 +365,10 @@ fn search_for_blockers_in_shadow_cubemap_hardware(
 
     return select(vec2(0.0), vec2(sampled_depth, 1.0), sampled_depth >= depth);
 
+#else   // PCSS_SAMPLERS_AVAILABLE
+    return vec2(0.0);
+#endif  // PCSS_SAMPLERS_AVAILABLE
+
 #endif  // WEBGL2
 }
 

examples/shader/extended_material.rs

@@ -32,7 +32,7 @@ fn setup(
         MeshMaterial3d(materials.add(ExtendedMaterial {
             base: StandardMaterial {
                 base_color: RED.into(),
-                // can be used in forward or deferred mode.
+                // can be used in forward or deferred mode
                 opaque_render_method: OpaqueRendererMethod::Auto,
                 // in deferred mode, only the PbrInput can be modified (uvs, color and other material properties),
                 // in forward mode, the output can also be modified after lighting is applied.