[Bf-blender-cvs] [6c2c3ed2c9b] master: Fix T101438: Wrong LOD selection after clamping the mip value (Nvidia)

[Miguel Pozo]

Commit: 6c2c3ed2c9befaef5a6402388732c1c2057f1787
Author: Miguel Pozo
Date:   Tue Oct 4 13:31:59 2022 +0200
Branches: master
https://developer.blender.org/rB6c2c3ed2c9befaef5a6402388732c1c2057f1787

Fix T101438: Wrong LOD selection after clamping the mip value (Nvidia)

Fix for T101438

Clamping the mip seems to always set it to 9.0.
I couldn't find an alternative way to avoid triggering the error (ie. min(mip, 9.0)).

In any case, the results with this patch applied look the same to the (correct) ones on AMD.
And, since clamping the max mip to a hardcoded value could result in resolution-depended behavior, I guess disabling the clamp should be ok anyway.

Reviewed By: fclem

Maniphest Tasks: T101438

Differential Revision: https://developer.blender.org/D16129

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M	source/blender/draw/engines/eevee/shaders/ssr_lib.glsl

===================================================================

diff --git a/source/blender/draw/engines/eevee/shaders/ssr_lib.glsl b/source/blender/draw/engines/eevee/shaders/ssr_lib.glsl
index a563291bb90..ea227ea9efd 100644
--- a/source/blender/draw/engines/eevee/shaders/ssr_lib.glsl
+++ b/source/blender/draw/engines/eevee/shaders/ssr_lib.glsl
@@ -79,7 +79,10 @@ vec4 screen_space_refraction(vec3 vP, vec3 N, vec3 V, float ior, float roughness
 
     /* Texel footprint */
     vec2 texture_size = vec2(textureSize(refractColorBuffer, 0).xy) / hizUvScale.xy;
-    float mip = clamp(log2(cone_footprint * max(texture_size.x, texture_size.y)), 0.0, 9.0);
+    float mip = log2(cone_footprint * max(texture_size.x, texture_size.y));
+
+    // Disabled. Causes incorrect LOD sampling on Nvidia cards. (T101438)
+    // mip = clamp(mip, 0.0, 9.0);
 
     vec3 spec = textureLod(refractColorBuffer, hit_uvs * hizUvScale.xy, mip).xyz;
     float mask = screen_border_mask(hit_uvs);