Photoshop cube maps in Fallout 3

Hand Creating Reflection Cube Maps for Fallout 3

with Ghogiel

Overview

A quick look at Cube Mapping as it pertains to Fallout 3 with a mini tutorial demonstrating how to make your own from normal images, with nothing more than Photoshop. This "tutorial" is largely my personal experiment, documented for the benefit of the community. Warning - this is not beginer friendly.

Apps:

photoshop

nvidia dds plugin

To make a cube map

Find an image with the scene of a landscape. (I don't do this in this tutorial, but before you start flip your base image vertically) Judge the area you wish to use. note its width in pixels. make a

new layer. Draw a square box selection on that image, with the dimensions of a bit less that 1/4 of the area you wish to use. fill selection with color. With snap turned on, clone the layer 5 more times and arrange them in this shape.

Make a new document, size it the height of one of your squares and x6 in length, you are going to arrange them all in a row. but first you need to know that each of your six images has its place in the running order, and then also has a particular rotation aswell.

Here I reversed engineered one of the vanilla Fallout 3 environment maps.

So from the new textures perspective, here is how each one of your six squared images that made up your cross, will need to be placed and rotated so that everything is displayed correctly in game.

from left to right

Image 1: is positive x.
rotated 90 clockwise

image 2: is negative x.
rotated 90 ccw

image 3: is positive z
not rotated

image 4: is negative z
rotated 180

image 5: is negative y
not rotated

image 6: is positive y
rotated 180

You can now edit the edges of the last 2 images, 5&6, so that they tile. I make them up from a composite. keep the 2 images you just made as a base, one edge already tiles perfectly, but now to edit the other 3 edges. You do this by taking edges from the 6 negative areas, marked here in grey.

I am going to tile the edge of image 5 with the edge of image 1. Go back to the original image. Make a new selection- just copy one of your original boxes and move it down a whole square. Copy that area of the base texture. rotate that new square exactly the same direction as the one that's above it, in this case- 90cw(reversed these rotations for tiling image 6s edges) Place this newly rotated section, directly over the one left to it. This new square will be one of the new edges we will create. Here is a demo of what we just did, I color coded the other edges, so you can see what edge is supposed to line up where.

Repeat for the other edges 2 on the bottom. Edit to blend all them together. Repeat again for the top, It'll make things easier if the top image is all blue sky.

While doing this you may have just understood why every image has a particular rotation.

Compile all the images together in the right order. Merge all the layers. Save as a dds. Select cube map from the drop down. mipmaps on. Leave the rest default.

Final result

Seamless....nearly.

However.... but looks like one of fallouts little quirks rears up- the sky is on the bottom and the ground is on the top. Well, to fix that, before you start, invert your base image vertically. Also before you start cutting out selections, tile the image horizontally. So the edge of image 2 and 4 are seamless. that way when they wrap around it'll blend. A lot of tiling isn't?. Mine had a little issue with tiling the nuber 6 image.

I can confirm that this is definitely how they aligned in game.