Add TransmissiveQuality enum to control number of taps

crates/bevy_core_pipeline/src/core_3d/camera_3d.rs

@@ -41,6 +41,9 @@ pub struct Camera3d {
     /// Setting this to `0` disables the screen-space refraction effect entirely, and falls
     /// back to refracting the environment map light's texture.
     pub transmissive_steps: usize,
+
+    /// The quality of the transmissive blur effect.
+    pub transmissive_quality: TransmissiveQuality,
 }
 
 impl Default for Camera3d {
@@ -50,6 +53,7 @@ impl Default for Camera3d {
             depth_load_op: Default::default(),
             depth_texture_usages: TextureUsages::RENDER_ATTACHMENT.into(),
             transmissive_steps: 1,
+            transmissive_quality: Default::default(),
         }
     }
 }
@@ -94,6 +98,34 @@ impl From<Camera3dDepthLoadOp> for LoadOp<f32> {
     }
 }
 
+/// The quality of the transmissive blur effect. Higher qualities are more GPU-intensive.
+///
+/// **Note:** You can get better-looking results at any quality level by enabling TAA. See: [`TemporalAntiAliasPlugin`](crate::experimental::taa::TemporalAntiAliasPlugin).
+#[derive(Resource, Default, Clone, Copy, Reflect, PartialEq, PartialOrd, Debug)]
+#[reflect(Resource)]
+pub enum TransmissiveQuality {
+    /// Best performance at the cost of quality. Suitable for lower end GPUs. (e.g. Mobile)
+    ///
+    /// `num_taps` = 4
+    Low,
+
+    /// A balanced option between quality and performance.
+    ///
+    /// `num_taps` = 8
+    #[default]
+    Medium,
+
+    /// Best quality. Suitable for high end GPUs. (e.g. Desktop)
+    ///
+    /// `num_taps` = 16
+    High,
+
+    /// The highest quality, suitable for non-realtime rendering. (e.g. Pre-rendered cinematics and photo mode)
+    ///
+    /// `num_taps` = 32
+    Ultra,
+}
+
 #[derive(Bundle)]
 pub struct Camera3dBundle {
     pub camera: Camera,

crates/bevy_pbr/src/material.rs

@@ -6,7 +6,9 @@ use crate::{
 use bevy_app::{App, Plugin};
 use bevy_asset::{Asset, AssetApp, AssetEvent, AssetId, AssetServer, Assets, Handle};
 use bevy_core_pipeline::{
-    core_3d::{AlphaMask3d, Opaque3d, Transmissive3d, Transparent3d},
+    core_3d::{
+        AlphaMask3d, Camera3d, Opaque3d, Transmissive3d, TransmissiveQuality, Transparent3d,
+    },
     prepass::NormalPrepass,
     tonemapping::{DebandDither, Tonemapping},
 };
@@ -423,6 +425,17 @@ const fn tonemapping_pipeline_key(tonemapping: Tonemapping) -> MeshPipelineKey {
     }
 }
 
+const fn transmissive_quality_pipeline_key(
+    transmissive_quality: TransmissiveQuality,
+) -> MeshPipelineKey {
+    match transmissive_quality {
+        TransmissiveQuality::Low => MeshPipelineKey::TRANSMISSIVE_QUALITY_LOW,
+        TransmissiveQuality::Medium => MeshPipelineKey::TRANSMISSIVE_QUALITY_MEDIUM,
+        TransmissiveQuality::High => MeshPipelineKey::TRANSMISSIVE_QUALITY_HIGH,
+        TransmissiveQuality::Ultra => MeshPipelineKey::TRANSMISSIVE_QUALITY_ULTRA,
+    }
+}
+
 #[allow(clippy::too_many_arguments)]
 pub fn queue_material_meshes<M: Material>(
     opaque_draw_functions: Res<DrawFunctions<Opaque3d>>,
@@ -451,6 +464,7 @@ pub fn queue_material_meshes<M: Material>(
         Option<&ScreenSpaceAmbientOcclusionSettings>,
         Option<&NormalPrepass>,
         Option<&TemporalJitter>,
+        Option<&Camera3d>,
         &mut RenderPhase<Opaque3d>,
         &mut RenderPhase<AlphaMask3d>,
         &mut RenderPhase<Transmissive3d>,
@@ -468,6 +482,7 @@ pub fn queue_material_meshes<M: Material>(
         ssao,
         normal_prepass,
         temporal_jitter,
+        camera_3d,
         mut opaque_phase,
         mut alpha_mask_phase,
         mut transmissive_phase,
@@ -502,6 +517,9 @@ pub fn queue_material_meshes<M: Material>(
         if ssao.is_some() {
             view_key |= MeshPipelineKey::SCREEN_SPACE_AMBIENT_OCCLUSION;
         }
+        if let Some(camera_3d) = camera_3d {
+            view_key |= transmissive_quality_pipeline_key(camera_3d.transmissive_quality);
+        }
         let rangefinder = view.rangefinder3d();
         for visible_entity in &visible_entities.entities {
             let Ok((material_handle, mut material_bind_group_id, mesh_handle, mesh_transforms)) =

crates/bevy_pbr/src/render/mesh.rs

@@ -729,6 +729,11 @@ bitflags::bitflags! {
         const TONEMAP_METHOD_SOMEWHAT_BORING_DISPLAY_TRANSFORM = 5 << Self::TONEMAP_METHOD_SHIFT_BITS;
         const TONEMAP_METHOD_TONY_MC_MAPFACE    = 6 << Self::TONEMAP_METHOD_SHIFT_BITS;
         const TONEMAP_METHOD_BLENDER_FILMIC     = 7 << Self::TONEMAP_METHOD_SHIFT_BITS;
+        const TRANSMISSIVE_QUALITY_RESERVED_BITS = Self::TRANSMISSIVE_QUALITY_MASK_BITS << Self::TRANSMISSIVE_QUALITY_SHIFT_BITS;
+        const TRANSMISSIVE_QUALITY_LOW          = 0 << Self::TRANSMISSIVE_QUALITY_SHIFT_BITS;
+        const TRANSMISSIVE_QUALITY_MEDIUM       = 1 << Self::TRANSMISSIVE_QUALITY_SHIFT_BITS;
+        const TRANSMISSIVE_QUALITY_HIGH         = 2 << Self::TRANSMISSIVE_QUALITY_SHIFT_BITS;
+        const TRANSMISSIVE_QUALITY_ULTRA        = 3 << Self::TRANSMISSIVE_QUALITY_SHIFT_BITS;
     }
 }
 
@@ -744,6 +749,9 @@ impl MeshPipelineKey {
     const TONEMAP_METHOD_MASK_BITS: u32 = 0b111;
     const TONEMAP_METHOD_SHIFT_BITS: u32 =
         Self::BLEND_SHIFT_BITS - Self::TONEMAP_METHOD_MASK_BITS.count_ones();
+    const TRANSMISSIVE_QUALITY_MASK_BITS: u32 = 0b11;
+    const TRANSMISSIVE_QUALITY_SHIFT_BITS: u32 =
+        Self::TONEMAP_METHOD_SHIFT_BITS - Self::TRANSMISSIVE_QUALITY_MASK_BITS.count_ones();
 
     pub fn from_msaa_samples(msaa_samples: u32) -> Self {
         let msaa_bits =
@@ -975,6 +983,19 @@ impl SpecializedMeshPipeline for MeshPipeline {
             shader_defs.push("TEMPORAL_JITTER".into());
         }
 
+        let transmissive_quality =
+            key.intersection(MeshPipelineKey::TRANSMISSIVE_QUALITY_RESERVED_BITS);
+
+        if transmissive_quality == MeshPipelineKey::TRANSMISSIVE_QUALITY_LOW {
+            shader_defs.push(ShaderDefVal::Int("TRANSMISSIVE_TAPS".into(), 4));
+        } else if transmissive_quality == MeshPipelineKey::TRANSMISSIVE_QUALITY_MEDIUM {
+            shader_defs.push(ShaderDefVal::Int("TRANSMISSIVE_TAPS".into(), 8));
+        } else if transmissive_quality == MeshPipelineKey::TRANSMISSIVE_QUALITY_HIGH {
+            shader_defs.push(ShaderDefVal::Int("TRANSMISSIVE_TAPS".into(), 16));
+        } else if transmissive_quality == MeshPipelineKey::TRANSMISSIVE_QUALITY_ULTRA {
+            shader_defs.push(ShaderDefVal::Int("TRANSMISSIVE_TAPS".into(), 32));
+        }
+
         let format = if key.contains(MeshPipelineKey::HDR) {
             ViewTarget::TEXTURE_FORMAT_HDR
         } else {

crates/bevy_pbr/src/render/pbr_lighting.wgsl

@@ -342,8 +342,11 @@ fn fetch_transmissive_background(offset_position: vec2<f32>, frag_coord: vec3<f3
     // - inversely proportional to view z
     let blur_intensity = (perceptual_roughness * perceptual_roughness) / view_z;
 
-    // TODO: Make this configurable
-    let num_taps = 8;
+#ifdef TRANSMISSIVE_TAPS
+    let num_taps = #{TRANSMISSIVE_TAPS}; // Controlled by the `Camera3d::transmissive_quality` property
+#else
+    let num_taps = 8; // Fallback to 8 taps
+#endif
     let num_spirals = i32(ceil(f32(num_taps) / 8.0));
     let random_angle = interleaved_gradient_noise(frag_coord.xy);