Bias texture mipmaps (#7614)

# Objective

- Closes #7323 
- Reduce texture blurriness for TAA

## Solution

- Add a `MipBias` component and view uniform.
- Switch material `textureSample()` calls to `textureSampleBias()`.
- Add a `-1.0` bias to TAA.

---

## Changelog

- Added `MipBias` camera component, mostly for internal use.

---------

Co-authored-by: François <mockersf@gmail.com>
Co-authored-by: Carter Anderson <mcanders1@gmail.com>

crates/bevy_core_pipeline/src/taa/mod.rs

@@ -10,14 +10,14 @@ use bevy_core::FrameCount;
 use bevy_ecs::{
     prelude::{Bundle, Component, Entity},
     query::{QueryItem, With},
-    schedule::IntoSystemConfigs,
+    schedule::{apply_deferred, IntoSystemConfigs},
     system::{Commands, Query, Res, ResMut, Resource},
     world::{FromWorld, World},
 };
 use bevy_math::vec2;
 use bevy_reflect::{Reflect, TypeUuid};
 use bevy_render::{
-    camera::{ExtractedCamera, TemporalJitter},
+    camera::{ExtractedCamera, MipBias, TemporalJitter},
     prelude::{Camera, Projection},
     render_graph::{NodeRunError, RenderGraphApp, RenderGraphContext, ViewNode, ViewNodeRunner},
     render_resource::{
@@ -65,7 +65,8 @@ impl Plugin for TemporalAntiAliasPlugin {
             .add_systems(
                 Render,
                 (
-                    prepare_taa_jitter
+                    (prepare_taa_jitter_and_mip_bias, apply_deferred)
+                        .chain()
                         .before(prepare_view_uniforms)
                         .in_set(RenderSet::Prepare),
                     prepare_taa_history_textures.in_set(RenderSet::Prepare),
@@ -140,6 +141,8 @@ pub struct TemporalAntiAliasBundle {
 /// are added using a third party library, the library must either:
 /// 1. Write particle motion vectors to the motion vectors prepass texture
 /// 2. Render particles after TAA
+///
+/// If no [`MipBias`] component is attached to the camera, TAA will add a MipBias(-1.0) component.
 #[derive(Component, Reflect, Clone)]
 pub struct TemporalAntiAliasSettings {
     /// Set to true to delete the saved temporal history (past frames).
@@ -436,9 +439,13 @@ fn extract_taa_settings(mut commands: Commands, mut main_world: ResMut<MainWorld
     }
 }
 
-fn prepare_taa_jitter(
+fn prepare_taa_jitter_and_mip_bias(
     frame_count: Res<FrameCount>,
-    mut query: Query<&mut TemporalJitter, With<TemporalAntiAliasSettings>>,
+    mut query: Query<
+        (Entity, &mut TemporalJitter, Option<&MipBias>),
+        With<TemporalAntiAliasSettings>,
+    >,
+    mut commands: Commands,
 ) {
     // Halton sequence (2, 3) - 0.5, skipping i = 0
     let halton_sequence = [
@@ -454,8 +461,12 @@ fn prepare_taa_jitter(
 
     let offset = halton_sequence[frame_count.0 as usize % halton_sequence.len()];
 
-    for mut jitter in &mut query {
+    for (entity, mut jitter, mip_bias) in &mut query {
         jitter.offset = offset;
+
+        if mip_bias.is_none() {
+            commands.entity(entity).insert(MipBias(-1.0));
+        }
     }
 }
 

crates/bevy_pbr/src/render/pbr.wgsl

@@ -55,7 +55,7 @@ fn fragment(in: FragmentInput) -> @location(0) vec4<f32> {
 #endif
 #ifdef VERTEX_UVS
     if ((material.flags & STANDARD_MATERIAL_FLAGS_BASE_COLOR_TEXTURE_BIT) != 0u) {
-        output_color = output_color * textureSample(base_color_texture, base_color_sampler, uv);
+        output_color = output_color * textureSampleBias(base_color_texture, base_color_sampler, uv, view.mip_bias);
     }
 #endif
 
@@ -74,7 +74,7 @@ fn fragment(in: FragmentInput) -> @location(0) vec4<f32> {
         var emissive: vec4<f32> = material.emissive;
 #ifdef VERTEX_UVS
         if ((material.flags & STANDARD_MATERIAL_FLAGS_EMISSIVE_TEXTURE_BIT) != 0u) {
-            emissive = vec4<f32>(emissive.rgb * textureSample(emissive_texture, emissive_sampler, uv).rgb, 1.0);
+            emissive = vec4<f32>(emissive.rgb * textureSampleBias(emissive_texture, emissive_sampler, uv, view.mip_bias).rgb, 1.0);
         }
 #endif
         pbr_input.material.emissive = emissive;
@@ -83,7 +83,7 @@ fn fragment(in: FragmentInput) -> @location(0) vec4<f32> {
         var perceptual_roughness: f32 = material.perceptual_roughness;
 #ifdef VERTEX_UVS
         if ((material.flags & STANDARD_MATERIAL_FLAGS_METALLIC_ROUGHNESS_TEXTURE_BIT) != 0u) {
-            let metallic_roughness = textureSample(metallic_roughness_texture, metallic_roughness_sampler, uv);
+            let metallic_roughness = textureSampleBias(metallic_roughness_texture, metallic_roughness_sampler, uv, view.mip_bias);
             // Sampling from GLTF standard channels for now
             metallic = metallic * metallic_roughness.b;
             perceptual_roughness = perceptual_roughness * metallic_roughness.g;
@@ -96,7 +96,7 @@ fn fragment(in: FragmentInput) -> @location(0) vec4<f32> {
         var occlusion: vec3<f32> = vec3(1.0);
 #ifdef VERTEX_UVS
         if ((material.flags & STANDARD_MATERIAL_FLAGS_OCCLUSION_TEXTURE_BIT) != 0u) {
-            occlusion = vec3(textureSample(occlusion_texture, occlusion_sampler, in.uv).r);
+            occlusion = vec3(textureSampleBias(occlusion_texture, occlusion_sampler, in.uv, view.mip_bias).r);
         }
 #endif
 #ifdef SCREEN_SPACE_AMBIENT_OCCLUSION

crates/bevy_pbr/src/render/pbr_functions.wgsl

@@ -82,7 +82,7 @@ fn apply_normal_mapping(
 #ifdef VERTEX_UVS
 #ifdef STANDARDMATERIAL_NORMAL_MAP
     // Nt is the tangent-space normal.
-    var Nt = textureSample(normal_map_texture, normal_map_sampler, uv).rgb;
+    var Nt = textureSampleBias(normal_map_texture, normal_map_sampler, uv, view.mip_bias).rgb;
     if (standard_material_flags & STANDARD_MATERIAL_FLAGS_TWO_COMPONENT_NORMAL_MAP) != 0u {
         // Only use the xy components and derive z for 2-component normal maps.
         Nt = vec3<f32>(Nt.rg * 2.0 - 1.0, 0.0);

crates/bevy_pbr/src/render/pbr_prepass.wgsl

@@ -39,7 +39,7 @@ fn prepass_alpha_discard(in: FragmentInput) {
 
 #ifdef VERTEX_UVS
     if (material.flags & STANDARD_MATERIAL_FLAGS_BASE_COLOR_TEXTURE_BIT) != 0u {
-        output_color = output_color * textureSample(base_color_texture, base_color_sampler, in.uv);
+        output_color = output_color * textureSampleBias(base_color_texture, base_color_sampler, in.uv, view.mip_bias);
     }
 #endif // VERTEX_UVS
 

crates/bevy_render/src/camera/camera.rs

@@ -771,3 +771,9 @@ impl TemporalJitter {
         projection.z_axis.y += jitter.y;
     }
 }
+
+/// Camera component specifying a mip bias to apply when sampling from material textures.
+///
+/// Often used in conjunction with antialiasing post-process effects to reduce textures blurriness.
+#[derive(Component)]
+pub struct MipBias(pub f32);

crates/bevy_render/src/view/mod.rs

@@ -6,7 +6,7 @@ pub use visibility::*;
 pub use window::*;
 
 use crate::{
-    camera::{ExtractedCamera, ManualTextureViews, TemporalJitter},
+    camera::{ExtractedCamera, ManualTextureViews, MipBias, TemporalJitter},
     extract_resource::{ExtractResource, ExtractResourcePlugin},
     prelude::{Image, Shader},
     render_asset::RenderAssets,
@@ -173,6 +173,7 @@ pub struct ViewUniform {
     // viewport(x_origin, y_origin, width, height)
     viewport: Vec4,
     color_grading: ColorGrading,
+    mip_bias: f32,
 }
 
 #[derive(Resource, Default)]
@@ -352,11 +353,16 @@ pub fn prepare_view_uniforms(
     render_device: Res<RenderDevice>,
     render_queue: Res<RenderQueue>,
     mut view_uniforms: ResMut<ViewUniforms>,
-    views: Query<(Entity, &ExtractedView, Option<&TemporalJitter>)>,
+    views: Query<(
+        Entity,
+        &ExtractedView,
+        Option<&TemporalJitter>,
+        Option<&MipBias>,
+    )>,
 ) {
     view_uniforms.uniforms.clear();
 
-    for (entity, camera, temporal_jitter) in &views {
+    for (entity, camera, temporal_jitter, mip_bias) in &views {
         let viewport = camera.viewport.as_vec4();
         let unjittered_projection = camera.projection;
         let mut projection = unjittered_projection;
@@ -383,6 +389,7 @@ pub fn prepare_view_uniforms(
                 world_position: camera.transform.translation(),
                 viewport,
                 color_grading: camera.color_grading,
+                mip_bias: mip_bias.unwrap_or(&MipBias(0.0)).0,
             }),
         };
 

crates/bevy_render/src/view/view.wgsl

@@ -19,4 +19,5 @@ struct View {
     // viewport(x_origin, y_origin, width, height)
     viewport: vec4<f32>,
     color_grading: ColorGrading,
+    mip_bias: f32,
 };