diff --git a/Source/Core/VideoBackends/Software/TransformUnit.cpp b/Source/Core/VideoBackends/Software/TransformUnit.cpp
index e1e6fd68a6..6fcf42df9e 100644
--- a/Source/Core/VideoBackends/Software/TransformUnit.cpp
+++ b/Source/Core/VideoBackends/Software/TransformUnit.cpp
@@ -97,6 +97,11 @@ void TransformNormal(const InputVertexData* src, OutputVertexData* dst)
   MultiplyVec3Mat33(src->normal[0], mat, dst->normal[0]);
   MultiplyVec3Mat33(src->normal[1], mat, dst->normal[1]);
   MultiplyVec3Mat33(src->normal[2], mat, dst->normal[2]);
+  // The scale of the transform matrix is used to control the size of the emboss map effect, by
+  // changing the scale of the transformed binormals (which only get used by emboss map texgens).
+  // By normalising the first transformed normal (which is used by lighting calculations and needs
+  // to be unit length), the same transform matrix can do double duty, scaling for emboss mapping,
+  // and not scaling for lighting.
   dst->normal[0].Normalize();
 }
 
diff --git a/Source/Core/VideoCommon/UberShaderVertex.cpp b/Source/Core/VideoCommon/UberShaderVertex.cpp
index c68c996b0a..40b4cd65e5 100644
--- a/Source/Core/VideoCommon/UberShaderVertex.cpp
+++ b/Source/Core/VideoCommon/UberShaderVertex.cpp
@@ -158,7 +158,11 @@ ShaderCode GenVertexShader(APIType api_type, const ShaderHostConfig& host_config
             "o.pos = float4(dot(" I_PROJECTION "[0], pos), dot(" I_PROJECTION
             "[1], pos), dot(" I_PROJECTION "[2], pos), dot(" I_PROJECTION "[3], pos));\n"
             "\n"
-            "// Only the first normal gets normalized (TODO: why?)\n"
+            "// The scale of the transform matrix is used to control the size of the emboss map\n"
+            "// effect by changing the scale of the transformed binormals (which only get used by\n"
+            "// emboss map texgens). By normalising the first transformed normal (which is used\n"
+            "// by lighting calculations and needs to be unit length), the same transform matrix\n"
+            "// can do double duty, scaling for emboss mapping, and not scaling for lighting.\n"
             "float3 _normal = float3(0.0, 0.0, 0.0);\n"
             "if ((components & {}u) != 0u) // VB_HAS_NORMAL\n",
             VB_HAS_NORMAL);
diff --git a/Source/Core/VideoCommon/VertexShaderGen.cpp b/Source/Core/VideoCommon/VertexShaderGen.cpp
index 0b176386e9..9fa2d6cd0e 100644
--- a/Source/Core/VideoCommon/VertexShaderGen.cpp
+++ b/Source/Core/VideoCommon/VertexShaderGen.cpp
@@ -258,7 +258,11 @@ ShaderCode GenerateVertexShaderCode(APIType api_type, const ShaderHostConfig& ho
     if ((uid_data->components & VB_HAS_BINORMAL) == 0)
       out.Write("float3 rawbinormal = " I_CACHED_BINORMAL ".xyz;\n");
 
-    // Only the first normal gets normalized (TODO: why?)
+    // The scale of the transform matrix is used to control the size of the emboss map effect, by
+    // changing the scale of the transformed binormals (which only get used by emboss map texgens).
+    // By normalising the first transformed normal (which is used by lighting calculations and needs
+    // to be unit length), the same transform matrix can do double duty, scaling for emboss mapping,
+    // and not scaling for lighting.
     out.Write("float3 _normal = normalize(float3(dot(N0, rawnormal), dot(N1, rawnormal), dot(N2, "
               "rawnormal)));\n"
               "float3 _tangent = float3(dot(N0, rawtangent), dot(N1, rawtangent), dot(N2, "