Using a 'window' images from the 'village' assets of Return to Castle Wolfenstein, the video above shows how textures can be used as a guide during the creation of more detailed or shaped meshes that can augment an already existing normal-mapped texture set (diffuse+normal+specular etc.)Scenario
In certain situations there might be a need for in-game structures to be modelled to contain more detail than can otherwise be had using normal-mapped texture sets assigned to flat plains. If textures already exist it might be possible to use them as a template or guide around which a model can be made in Blender (or other application with the following support).Problem
In wanting to use pre-existing textures as a basis from which game models are to be made (and mapped using said-same images employed to make the mesh), editing can be tricky because UVW mapping tends not to be held in place during the generally 'destructive' modelling process - adding and moving edge-loops might shift or distort any UVW maps previously assigned for example. Whilst Blender has a number of properties available that might otherwise ease the UVW map distortion issue in a general sense, they do not always have a practical application. Ideally, rather than trying to prevent the problem the artist might find it better to 'ignore' it whilst being able to 'see' the texture at all time. Solution
A 'see-through' mesh can be facilitated by making a duplication of an original Object (always work on a copy) and making any assigned assigned Material/s 'unique' (Single User data-blocks). Once done activate material "Transparency
" and reduce the value of the property so the mesh becomes see-through thus allowing the mesh to be editable in Edit mode; the mesh can be shaped whilst the original textured version is visible as a guide.