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          Parallax Mapping Mod v1.0

 Custom Parallax Mapped Level Textures Tutorial

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by Junkguy


Parallax mapping requires the use of height maps to determine how
much offset is applied to different parts of a texture.  Since most 
of Doom3's textures do not have any height maps, this mod uses the
bump maps (or "normal maps") for height information.  

In this mod, the red and green color channels in the normal maps are still 
used for regular bump mapping, but the mod uses the inverse of the 
blue channel as a heightmap.

With the default normal maps in Doom3, this technique will cause angled 
parts of the normal map to be bumped out, while the flat parts remain low.  
This is what I call simulated parallax mapping. It looks great for most 
surfaces, and it is all handled by the mod's pixel shader code.

True parallax mapping occurs when you put the actual correct heightmap 
into the blue channel of the normal map.  However, ensure that you invert 
it.  The low elevations in the blue channel's heightmap will then be almost 
white, while the higher parts will be dark.

This is what you should do if you want your level's custom textures to 
take advantage of this mod's parallax mapping.  Please note, however, 
that doing this will require the player to be using this mod, otherwise 
the custom textures will be incorrectly lit.

If you don't want to make your own height maps for your textures, the 
mod will automatically apply simulated parallax mapping
.


So now that you understand how the mod works, you can make your level's 
textures take advantage of true parallax mapping.  The following explains 
how to put a heightmap into the normal map's blue channel if you don't 
know how.

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See http://www.doom3world.org/phpbb2/viewtopic.php?t=2659 for basic
tutorials on how to make regular textures and bump maps for Doom 3.

1. 
Make a greyscale height map for your texture.  For a regular height 
map like this, dark is low elevation and white is high elevation.  Make 
sure that the height map isn't too extreme (like pure white and pure 
black), otherwise it may look strange in game.

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NOTE

If you have a normal map, and want to create the heightmap for 
it, you can use the Normal Map plugin from step 2, and 
use its "Convert to Height" option with the Scale setting of around 1.
If the heightmap looks correct, go to step 3.  If the heightmap looks
already inverted, go to step 4 instead.  If the heightmap looks 
completely messed up, go back to the normal map do the following:

You can use the default blue channel of the normal map, invert it 
so its mostly black, and manually fill in brighter greys for the 
higher elevations.  Re-invert its colors again, and you're done!
You can then skip the rest of this tutorial.

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2. 
If you don't already have a normal map, create the normal map from the 
height map using Nvidia's Normal Map Filter plugin for Photoshop 
(get it at http://developer.nvidia.com/object/nv_texture_tools.html ).
You might need to use a large Scale setting of 100 or 1000.  
Don't lose the original height map!

3. 
Invert the colors of the original heightmap, so that white is low 
elevation and dark is high elevation

4. 
Copy the contents of the inverted heightmap (Using Photoshop, 
select all and copy)

5. 
In the normal map, go to the blue color channel (Using Photoshop, click 
Window -> Channels, and click the Blue channel in the channels window)

6. 
Paste the inverted heightmap into the blue channel of the normal map

7. 
Save the normal map


That's it! Now you can use your new normalmap/heightmap in your level,
and it will have a nice parallax effect when you use this mod! Please
note that you may not include this mod's shader in your level without
my permission.  Remember
 that players MUST use this mod for the custom 
textures to appear correctly, so make sure you mention this fact in the 
level's description. I would appreciate it if you email me at 
junkguy@gmail.com to tell me about it, so I can take a look! :)