Expose ssao radius

crates/bevy_pbr/src/ssao/mod.rs

@@ -115,22 +115,38 @@ impl Plugin for ScreenSpaceAmbientOcclusionPlugin {
 pub struct ScreenSpaceAmbientOcclusion {
     /// Quality of the SSAO effect.
     pub quality_level: ScreenSpaceAmbientOcclusionQualityLevel,
+    /// Maximum sample distance, in view-space units.
+    ///
+    /// Use larger values for broader occlusion. This can increase haloing and noise.
+    /// This value must be greater than `0.0`.
+    ///
+    /// To disable SSAO, remove [`ScreenSpaceAmbientOcclusion`] from the camera instead.
+    pub radius: f32,
     /// A constant estimated thickness of objects.
     ///
     /// This value is used to decide how far behind an object a ray of light needs to be in order
     /// to pass behind it. Any ray closer than that will be occluded.
     pub constant_object_thickness: f32,
 }
 
+const DEFAULT_SSAO_RADIUS: f32 = 0.5 * 1.457;
+
 impl Default for ScreenSpaceAmbientOcclusion {
     fn default() -> Self {
         Self {
             quality_level: ScreenSpaceAmbientOcclusionQualityLevel::default(),
+            radius: DEFAULT_SSAO_RADIUS,
             constant_object_thickness: 0.25,
         }
     }
 }
 
+#[derive(Clone, Copy, ShaderType)]
+struct SsaoSettingsUniform {
+    radius: f32,
+    constant_object_thickness: f32,
+}
+
 #[derive(Reflect, PartialEq, Eq, Hash, Clone, Copy, Default, Debug)]
 #[reflect(PartialEq, Hash, Clone, Default)]
 pub enum ScreenSpaceAmbientOcclusionQualityLevel {
@@ -368,7 +384,7 @@ impl FromWorld for SsaoPipelines {
                     texture_storage_2d(depth_format, StorageTextureAccess::WriteOnly),
                     texture_storage_2d(TextureFormat::R32Uint, StorageTextureAccess::WriteOnly),
                     uniform_buffer::<GlobalsUniform>(false),
-                    uniform_buffer::<f32>(false),
+                    uniform_buffer::<SsaoSettingsUniform>(false),
                 ),
             ),
         );
@@ -508,7 +524,7 @@ pub struct ScreenSpaceAmbientOcclusionResources {
     ssao_noisy_texture: CachedTexture, // Pre-spatially denoised texture
     pub screen_space_ambient_occlusion_texture: CachedTexture, // Spatially denoised texture
     depth_differences_texture: CachedTexture,
-    thickness_buffer: Buffer,
+    settings_buffer: Buffer,
 }
 
 fn prepare_ssao_textures(
@@ -580,9 +596,17 @@ fn prepare_ssao_textures(
             },
         );
 
-        let thickness_buffer = render_device.create_buffer_with_data(&BufferInitDescriptor {
-            label: Some("thickness_buffer"),
-            contents: &ssao_settings.constant_object_thickness.to_le_bytes(),
+        let mut settings_uniform_buffer = encase::UniformBuffer::new(Vec::new());
+        settings_uniform_buffer
+            .write(&SsaoSettingsUniform {
+                radius: ssao_settings.radius,
+                constant_object_thickness: ssao_settings.constant_object_thickness,
+            })
+            .unwrap();
+
+        let settings_buffer = render_device.create_buffer_with_data(&BufferInitDescriptor {
+            label: Some("ssao_settings_buffer"),
+            contents: settings_uniform_buffer.as_ref(),
             usage: BufferUsages::UNIFORM,
         });
 
@@ -593,7 +617,7 @@ fn prepare_ssao_textures(
                 ssao_noisy_texture,
                 screen_space_ambient_occlusion_texture: ssao_texture,
                 depth_differences_texture,
-                thickness_buffer,
+                settings_buffer,
             });
     }
 }
@@ -698,7 +722,7 @@ fn prepare_ssao_bind_groups(
                 &ssao_resources.ssao_noisy_texture.default_view,
                 &ssao_resources.depth_differences_texture.default_view,
                 globals_uniforms.clone(),
-                ssao_resources.thickness_buffer.as_entire_binding(),
+                ssao_resources.settings_buffer.as_entire_binding(),
             )),
         );
 

crates/bevy_pbr/src/ssao/ssao.wgsl

@@ -28,7 +28,11 @@
 #endif
 @group(0) @binding(4) var depth_differences: texture_storage_2d<r32uint, write>;
 @group(0) @binding(5) var<uniform> globals: Globals;
-@group(0) @binding(6) var<uniform> thickness: f32;
+struct SsaoSettings {
+    radius: f32,
+    thickness: f32,
+}
+@group(0) @binding(6) var<uniform> settings: SsaoSettings;
 @group(1) @binding(0) var point_clamp_sampler: sampler;
 @group(1) @binding(1) var linear_clamp_sampler: sampler;
 @group(1) @binding(2) var<uniform> view: View;
@@ -116,7 +120,7 @@ fn processSample(
     samples_per_slice: f32,
     bitmask: ptr<function, u32>,
 ) {
-    let delta_position_back_face = delta_position - view_vec * thickness;
+    let delta_position_back_face = delta_position - view_vec * settings.thickness;
 
     var front_back_horizon = vec2(
         fast_acos(dot(normalize(delta_position), view_vec)),
@@ -134,11 +138,6 @@ fn processSample(
 fn ssao(@builtin(global_invocation_id) global_id: vec3<u32>) {
     let slice_count = f32(#SLICE_COUNT);
     let samples_per_slice_side = f32(#SAMPLES_PER_SLICE_SIDE);
-    let effect_radius = 0.5 * 1.457;
-    let falloff_range = 0.615 * effect_radius;
-    let falloff_from = effect_radius * (1.0 - 0.615);
-    let falloff_mul = -1.0 / falloff_range;
-    let falloff_add = falloff_from / falloff_range + 1.0;
 
     let pixel_coordinates = vec2<i32>(global_id.xy);
     let uv = (vec2<f32>(pixel_coordinates) + 0.5) / view.viewport.zw;
@@ -151,7 +150,8 @@ fn ssao(@builtin(global_invocation_id) global_id: vec3<u32>) {
     let view_vec = normalize(-pixel_position);
 
     let noise = load_noise(pixel_coordinates);
-    let sample_scale = (-0.5 * effect_radius * view.clip_from_view[0][0]) / pixel_position.z;
+    let safe_radius = max(settings.radius, 0.0001);
+    let sample_scale = (-0.5 * safe_radius * view.clip_from_view[0][0]) / pixel_position.z;
 
     var visibility = 0.0;
     var occluded_sample_count = 0u;

examples/3d/ssao.rs

@@ -151,6 +151,20 @@ fn update(
                 ..current_ssao
             },
             || keycode.just_pressed(KeyCode::ArrowDown),
+        )
+        .insert_if(
+            ScreenSpaceAmbientOcclusion {
+                radius: (current_ssao.radius * 1.25).min(8.0),
+                ..current_ssao
+            },
+            || keycode.just_pressed(KeyCode::ArrowRight),
+        )
+        .insert_if(
+            ScreenSpaceAmbientOcclusion {
+                radius: (current_ssao.radius * 0.8).max(0.1),
+                ..current_ssao
+            },
+            || keycode.just_pressed(KeyCode::ArrowLeft),
         );
     if keycode.just_pressed(KeyCode::Digit1) {
         commands.remove::<ScreenSpaceAmbientOcclusion>();
@@ -174,6 +188,10 @@ fn update(
         _ => unreachable!(),
     };
 
+    if let Some(radius) = ssao.map(|s| s.radius) {
+        text.push_str(&format!("Radius: {radius} (Left/Right)\n"));
+    }
+
     if let Some(thickness) = ssao.map(|s| s.constant_object_thickness) {
         text.push_str(&format!(
             "Constant object thickness: {thickness} (Up/Down)\n\n"