Solari: Support clear color (#21350)

<img width="2564" height="1500" alt="image"
src="https://github.com/user-attachments/assets/8bd37bda-88b0-436a-9c01-a22fb63e9e87"
/>

* ClearColor is not supported for the pathtracer still
* Tonemapping makes the clear color appear incorrect (the above image is
supposed to be pure white), which is a little wonky. That's a separate
issue though.

Author: JMS55

crates/bevy_solari/src/realtime/node.rs

@@ -23,8 +23,8 @@ use bevy_render::{
             storage_buffer_sized, texture_2d, texture_depth_2d, texture_storage_2d, uniform_buffer,
         },
         BindGroupEntries, BindGroupLayout, BindGroupLayoutEntries, CachedComputePipelineId,
-        ComputePassDescriptor, ComputePipelineDescriptor, PipelineCache, PushConstantRange,
-        ShaderStages, StorageTextureAccess, TextureFormat, TextureSampleType,
+        ComputePassDescriptor, ComputePipelineDescriptor, LoadOp, PipelineCache, PushConstantRange,
+        RenderPassDescriptor, ShaderStages, StorageTextureAccess, TextureFormat, TextureSampleType,
     },
     renderer::{RenderContext, RenderDevice},
     view::{ViewTarget, ViewUniform, ViewUniformOffset, ViewUniforms},
@@ -156,12 +156,14 @@ impl ViewNode for SolariLightingNode {
             return Ok(());
         };
 
+        let view_target = view_target.get_unsampled_color_attachment();
+
         let s = solari_lighting_resources;
         let bind_group = render_context.render_device().create_bind_group(
             "solari_lighting_bind_group",
             &self.bind_group_layout,
             &BindGroupEntries::sequential((
-                view_target.get_unsampled_color_attachment().view,
+                view_target.view,
                 s.light_tile_samples.as_entire_binding(),
                 s.light_tile_resolved_samples.as_entire_binding(),
                 &s.di_reservoirs_a.1,
@@ -212,6 +214,17 @@ impl ViewNode for SolariLightingNode {
         let diagnostics = render_context.diagnostic_recorder();
         let command_encoder = render_context.command_encoder();
 
+        // Clear the view target if we're the first node to write to it
+        if matches!(view_target.ops.load, LoadOp::Clear(_)) {
+            command_encoder.begin_render_pass(&RenderPassDescriptor {
+                label: Some("solari_lighting_clear"),
+                color_attachments: &[Some(view_target)],
+                depth_stencil_attachment: None,
+                timestamp_writes: None,
+                occlusion_query_set: None,
+            });
+        }
+
         let mut pass = command_encoder.begin_compute_pass(&ComputePassDescriptor {
             label: Some("solari_lighting"),
             timestamp_writes: None,

crates/bevy_solari/src/realtime/restir_di.wgsl

@@ -68,7 +68,6 @@ fn spatial_and_shade(@builtin(global_invocation_id) global_id: vec3<u32>) {
     let depth = textureLoad(depth_buffer, global_id.xy, 0);
     if depth == 0.0 {
         store_reservoir_a(global_id.xy, empty_reservoir());
-        textureStore(view_output, global_id.xy, vec4(vec3(0.0), 1.0));
         return;
     }
     let gpixel = textureLoad(gbuffer, global_id.xy, 0);