From baa88b98a36bf0af584a135cd30bd5847e4c2d4e Mon Sep 17 00:00:00 2001
From: atlv <rodol@rivalrebels.com>
Date: Sun, 6 Jul 2025 15:13:10 -0400
Subject: [PATCH] fix variable-termination loop gradients by sampling specific
 lod (#19988)

# Objective

- Calculating gradients in variable-termination loop is bad, and we dont
need to here

## Solution

- Sample mip 0 always

## Testing

- volumetric_fog example
---
 crates/bevy_pbr/src/volumetric_fog/volumetric_fog.wgsl | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/crates/bevy_pbr/src/volumetric_fog/volumetric_fog.wgsl b/crates/bevy_pbr/src/volumetric_fog/volumetric_fog.wgsl
index 058f73fca9..43e3fc9278 100644
--- a/crates/bevy_pbr/src/volumetric_fog/volumetric_fog.wgsl
+++ b/crates/bevy_pbr/src/volumetric_fog/volumetric_fog.wgsl
@@ -251,7 +251,7 @@ fn fragment(@builtin(position) position: vec4<f32>) -> @location(0) vec4<f32> {
             // case.
             let P_uvw = Ro_uvw + Rd_step_uvw * f32(step);
             if (all(P_uvw >= vec3(0.0)) && all(P_uvw <= vec3(1.0))) {
-                density *= textureSample(density_texture, density_sampler, P_uvw + density_texture_offset).r;
+                density *= textureSampleLevel(density_texture, density_sampler, P_uvw + density_texture_offset, 0.0).r;
             } else {
                 density = 0.0;
             }