Revert "Fix Blend Mode on Terrain materials to be unenviable due to not implemented"

This reverts commit 641f70d4ac.

Transparent material on terrain is used by terrain brushes and terrain highlight tools in editor.

Source/Engine/Graphics/Materials/TerrainMaterialShader.cpp

@@ -150,6 +150,21 @@ bool TerrainMaterialShader::Load()
     }
 #endif
 
+    // Support blending but then use only emissive channel
+    switch (_info.BlendMode)
+    {
+    case MaterialBlendMode::Transparent:
+        psDesc.BlendMode = BlendingMode::AlphaBlend;
+        break;
+    case MaterialBlendMode::Additive:
+        psDesc.BlendMode = BlendingMode::Additive;
+        break;
+    case MaterialBlendMode::Multiply:
+        psDesc.BlendMode = BlendingMode::Multiply;
+        break;
+    default: ;
+    }
+
     // GBuffer Pass
     psDesc.VS = _shader->GetVS("VS");
     psDesc.PS = _shader->GetPS("PS_GBuffer");
@@ -170,6 +185,7 @@ bool TerrainMaterialShader::Load()
 
     // Depth Pass
     psDesc.CullMode = CullMode::TwoSided;
+    psDesc.BlendMode = BlendingMode::Opaque;
     psDesc.DepthClipEnable = false;
     psDesc.DepthWriteEnable = true;
     psDesc.DepthEnable = true;