Tip [Winmip2] Do not resave mip files

A quick tip you can learn to improve or setup NR2003 or related tool/program
This is not a well known bug but it is an easy error to make. In many cases most track and mod makers in the NR2003 community may not even have realized this over the years. Through thorough observations and testing myself I have noticed the issue and want to spread the word so everyone can be aware of this mip re-saving bug.


The bug

In some cases you might have created a mip file for a track object decal or 3do or a mod and after creating the mip you realize you need to re-open and re-save the mip changing a setting (maybe you forgot to set transparency or the texture tiling option. It has been found each time a mip is re-saved the image get slightly darker each time you save the mip over and over again. In most cases it will negligible and not noticed by the user. However, there are several types of mips this can be detrimental to where the brightness of the image is import. For example a few type of texture fiels where brightness level is important:
  • Transparency maps
  • Specular maps
  • Shadow maps
All of these generally are based on black and while values where the specific level is important or the model/texture will look incorrect in NR2003/Sandbox.




Examples

The best way to show this is with a shadow map. Shadow maps heavily rely on 100% white level for all areas of the shadow map where a shadow does NOT appear. For example here is a shadow map that was just created in winmip2:

1671230538968.png

Now let us simply re-save the file again, then reopen the same mip in winmip2:

1671230565420.png

See the different between the re-saved and newly create brightness levels? What happens if we save the file 5 more times in a row changing no settings?

1671230621675.png

Big difference compared to the first image right?


This bug is so subtle it has evaded many creators in the NR2003 community for years unless you have an eagle eye to spot it. For example even some of the well known NR2003 tracks have this bug. Look at Daytona Day SDT for example:
1671230818088.png

1671230849215.png

See how a large section of the shadow on the racing groove looks like a giant dark patch? That is the shadow map that was re-saved at least once and made the whole mip darker.

While no example images shown here if you have a model with a specular map and you re-saved the map many times that can make the shiny level of your model darker than you intended. Or with a transparency map a texture which should be 100% opaque now becomes see-through (semi-transparent).



The Solution

The conclusion here is if you need to change a setting simply recreate the mip with your original source texture files, double check all what settings for your mip are and what you need before saving. Re-saving will cause bugs with your textures.
 
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