Import: 71091 sl 20703 pbr masked alpha gradient textures change with viewing angle

indra/newview/llfetchedgltfmaterial.cpp

@@ -78,7 +78,14 @@ void LLFetchedGLTFMaterial::bind(LLViewerTexture* media_tex)
         {
             // dividing the alpha cutoff by transparency here allows the shader to compare against
             // the alpha value of the texture without needing the transparency value
-            min_alpha = mAlphaCutoff/mBaseColor.mV[3];
+            if (mBaseColor.mV[3] > 0.f)
+            {
+                min_alpha = mAlphaCutoff / mBaseColor.mV[3];
+            }
+            else
+            {
+                min_alpha = 1024.f;
+            }
         }
         shader->uniform1f(LLShaderMgr::MINIMUM_ALPHA, min_alpha);
     }