Someone recently asked me how to make skies using Bryce 3D which is sort of a modeling/rendering tool. I haven't done this in a number of years, but the information should still apply and be useful to someone. So below is a tutorial on creating sky texture using Bryce 3D as I used for Soldier of Fortune 1.
The hardest part about making skies is creating the 6 textures of the cube so that when they are pieced together in the game, you don't see any seams in the corners. Since we can adjust the camera settings in Bryce 3d (and most modeling/image rendering programs), this makes it an excellent tool for such a task.
If you are unfamiliar with how skies work within the game (at least for Quake-based games), a sky consists of 6 textures: forward, back, left, right, top, bottom. They are projected onto the 6 inner walls of a cube. The trick in making the sky textures seamless is in setting the camera to not only take-in a full 90 degrees (90 * 4 = 360 degrees) on each shot, but to also squish the edges to adjust for the squareness of the cube.
Let me begin with the steps you must take in order to come out with a usable product.
To setup the document (environment) you need to begin by settinghhte aspect ratio. When you go to the File menu and into Document setup, you will find a list of aspect ratios (render resolution) and you want to pick SQUARE. This will make the aspect ratio 1:1 so that all sides of your final image are the same.
While you have this window open, also select the final resolution. The standard used to by 512 x 512, but as games and computers get better, resolution increases. After you check into what your game supports, select that resolution (probably 1024 x 1024).
Close this window when you are done.
Next we want to setup the camera attributes. To do this, we need to select the camera and that can be done by changing your view to anything other than camera. This way you can see the camera rather than see through it. When you see the camera, select it and open up the window for camera attributes ("A").
With the atributes window open, set all the rotation axis' to zero.. except for the Y axis. The Y axis will allow us to adjust the height of the camera. We don't want to be peering thought the dirt so we will need to move the camera up (Y axis) and off the ground.
Go ahead and set the Y axis to something. Perhaps "4" is a good place to start.
Set the field of view (FOV) to 90 degrees. This means that you will get a full 1/4 of a circle into your final image (90 * 4 = 360 degrees).
Set the viewing scale to 72 percent. This means that 72 percent of the FOV is normal and the rest is squeezed in to give our square texture a 'round' appearance. This is what caused the seams to disappear.
*note: If I remember correctly, I had to play around with the viewing angle to make my final sky images perfect. I don't remember 72 percent being the ideal number, but it's a good place to start.
Go into the Sky & Fog sectings and select "Edit Sky/Fog" from the pull-down menu.
Make sure that the option "Link sun to view" is turned off. This means that the sun in your sky will stay in one place. See, Bryce is setup to adjust the sun according the angle of the camera. The program assumes you are attempting to make a single screenshot. You need to tell it that the sun should stay in one place while the camera moves around the scene.
Finally you can go ahead and put your scene together with the trees, mountains, etc.
Once the scene is complete, continue on below...
Remember that our goal here is to create the 6 images that fit inside of the cube. As long as your camera still has the X,Y, and Z rotations (angles) set to zero, you're ready to render your first image. So... set the camera rotations as follows and start rendering your sky:
X = 0 Y = 0 Z = 0 Render and save as front image
X = 0
Y = 90
Z = 0
Render and save as right image
X = 0
Y = 180
Z = 0
Render and save as back image
X = 0
Y = 270
Z = 0
Render and save as left image
X = 90
Y = 90
Z = 0
Render and save as bottom image
X = 270
Y = 270
Z = 0
Render and save as top image
Again, this process of setting the angles will need compensation. Each game seems to have the image in a specific rotation. Example: the top image might need to be spun around to line up with the sides.
You can make these adjustment in your photo editing program such as Adobe Photoshop.
The final step is dependant on your game. You now just need to properly name each file, place them in the coresponding directories, and create a shader or sky file. This is specific to each game and cannot be properly covered in this tutorial.
I hope this has been helpful to you and remember to post your custom skies in the downloads section here on this site for others to enjoy.
This tutorial was modeled after another tutorial written years ago by [PnC]Muzma. I originally found it on telefragged.com.
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