How to create Mix Maps in Photoshop for Reality Engine

Tutorial Author:Clifton Poli

Note: The mixmap shader supports 4 diffuse textures in the mix, this tutorial covers how to make a mixmap using all 4 channels. However you do not have to use 4 textures and can instead use 3 or 2, it is simply a matter of not painting the unused channels into the mixmap, and using a pure black texture in the corresponding texture slots in the shader.

Note: Make sure your base diffuse texture has a black/grey-coloured alpha channel.

1. In PS create a new file with power of 2 dimensions, such as 2048x2048. Make sure your background layer is black.

2. Now click on the channels tab. If there is no alpha channel, click the new channel icon at the bottom of the tool window. You now have four channels. Each of these corresponds to one texture layer this mixmap controls. Black for any channel means none of the texture is blended, while white is full blending.

3. There is 2 ways you can paint each mix 'layer' You can select and paint each channel individually, or you can paint in the RGB channel by painting with pure RGB colors, 255 for Red, Green, and Blue respectively. I think it helps to use a layer for each color and one for the alpha. Concerning the alpha channel, if your painting in the RGB channel you can represent the alpha mix layer as pure black, then when your done just select all the black, paste it into the alpha channel and invert it. You should then have something that looks like this: * mixmapexamples1.png:

4. If you want to have a smooth transition between your layers/channels simply apply a gausion blur to the RGB channel, and then apply it again too the alpha channel with the same settings (so they match up). * mixmapexample3.png:

5. Now you need to save your mix map as a 32 bit .TGA, or if you did not use the alpha channel save it as 24 bit .TGA.

The mix shader itself has the following slots.

Note: All layers are multiply blended.

Name	Type	Description
tDiffuse0	Texture	Base texture for entire terrain. Should not be tiled. Not mixed by mixmap
tMixMap	Texture	Mixmap texture, described above
Layer1	Texture	Mix Layer #1 (Red Channel)
Layer2	Texture	Mix Layer #2 (Green Channel)
Layer3	Texture	Mix Layer #3 (Blue Channel)
Layer4	Texture	Mix Layer #4 (Alpha Channel)
Layer12UTile	U Tiling	U Tiling for layers 1 and 2
Layer12VTile	V Tiling	V Tiling for layers 1 and 2
Layer34UTile	U Tiling	U Tiling for layers 3 and 4
Layer34VTile	V Tiling	V Tiling for layers 3 and 4

Attachment	Action	Size	Date	Who	Comment
mixmapexample1.jpg	manage	58.9 K	01 Sep 2004 - 19:14	Main.guest
terrain3.jpg	manage	21.6 K	10 Oct 2004 - 23:49	Main.guest	Mixmap Thumb
mixmapexamples.png	manage	497.8 K	30 Nov 2005 - 18:19	Main.guest
mixmapexample3.png	manage	528.4 K	01 Dec 2005 - 02:27	Main.guest
mixmapexamples1.png	manage	17.9 K	03 Dec 2005 - 00:24	Main.guest

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